def blocks(self, reader=None):
"""yields (length, reader) tuples of WavPack frames
length is the total length of all the substreams
reader is a BitstreamReader which can be parsed
"""
def blocks_iter(reader):
try:
while (True):
(wvpk, block_size) = reader.parse("4b 32u 192p")
if (wvpk == 'wvpk'):
yield (block_size - 24,
reader.substream(block_size - 24))
else:
return
except IOError:
return
if (reader is None):
from audiotools.bitstream import BitstreamReader
reader = BitstreamReader(open(self.filename), 1)
try:
for block in blocks_iter(reader):
yield block
finally:
reader.close()
else:
for block in blocks_iter(reader):
yield block
def blocks(self, reader=None):
"""yields (length, reader) tuples of WavPack frames
length is the total length of all the substreams
reader is a BitstreamReader which can be parsed
"""
def blocks_iter(reader):
try:
while (True):
(wvpk, block_size) = reader.parse("4b 32u 192p")
if (wvpk == 'wvpk'):
yield (block_size - 24,
reader.substream(block_size - 24))
else:
return
except IOError:
return
if (reader is None):
from audiotools.bitstream import BitstreamReader
reader = BitstreamReader(open(self.filename), 1)
try:
for block in blocks_iter(reader):
yield block
finally:
reader.close()
else:
for block in blocks_iter(reader):
yield block
def perform_lookup(disc_id,
accuraterip_server="www.accuraterip.com",
accuraterip_port=80):
"""performs web-based lookup using the given DiscID object
and returns a dict of
{track_number:[(confidence, crc, crc2), ...], ...}
where track_number starts from 1
may return a dict of empty lists if no AccurateRip entry is found
may raise urllib2.HTTPError if an error occurs querying the server
"""
from audiotools.bitstream import BitstreamReader
try:
from urllib.request import urlopen, URLError
except ImportError:
from urllib2 import urlopen, URLError
matches = {n: [] for n in disc_id.track_numbers()}
url = "http://%s:%s/accuraterip/%s/%s/%s/%s" % (accuraterip_server,
accuraterip_port,
str(disc_id)[16],
str(disc_id)[15],
str(disc_id)[14],
disc_id)
try:
response = BitstreamReader(urlopen(url), True)
except URLError:
# no CD found matching given parameters
return matches
try:
while True:
(track_count,
id1,
id2,
freedb_disc_id) = response.parse("8u 32u 32u 32u")
if (((id1 == disc_id.id1()) and
(id2 == disc_id.id2()) and
(freedb_disc_id == disc_id.freedb_disc_id()))):
for track_number in range(1, track_count + 1):
if track_number in matches:
matches[track_number].append(
tuple(response.parse("8u 32u 32u")))
except IOError:
# keep trying to parse values until the data runs out
response.close()
return matches
def perform_lookup(disc_id,
accuraterip_server="www.accuraterip.com",
accuraterip_port=80):
"""performs web-based lookup using the given DiscID object
and returns a dict of
{track_number:[(confidence, crc, crc2), ...], ...}
where track_number starts from 1
may return a dict of empty lists if no AccurateRip entry is found
may raise urllib2.HTTPError if an error occurs querying the server
"""
from audiotools.bitstream import BitstreamReader
try:
from urllib.request import urlopen, URLError
except ImportError:
from urllib2 import urlopen, URLError
matches = {n: [] for n in disc_id.track_numbers()}
url = "http://%s:%s/accuraterip/%s/%s/%s/%s" % (accuraterip_server,
accuraterip_port,
str(disc_id)[16],
str(disc_id)[15],
str(disc_id)[14],
disc_id)
try:
response = BitstreamReader(urlopen(url), True)
except URLError:
# no CD found matching given parameters
return matches
try:
while (True):
(track_count,
id1,
id2,
freedb_disc_id) = response.parse("8u 32u 32u 32u")
if (((id1 == disc_id.id1()) and
(id2 == disc_id.id2()) and
(freedb_disc_id == disc_id.freedb_disc_id()))):
for track_number in range(1, track_count + 1):
if (track_number in matches):
matches[track_number].append(
tuple(response.parse("8u 32u 32u")))
except IOError:
# keep trying to parse values until the data runs out
response.close()
return matches
class FlacDecoder(object):
CHANNEL_COUNT = [
1, 2, 3, 4, 5, 6, 7, 8, 2, 2, 2, None, None, None, None, None
]
(SUBFRAME_CONSTANT, SUBFRAME_VERBATIM, SUBFRAME_FIXED,
SUBFRAME_LPC) = range(4)
def __init__(self, filename, channel_mask):
self.reader = BitstreamReader(open(filename, "rb"), False)
if (self.reader.read_bytes(4) != b'fLaC'):
raise ValueError("invalid FLAC file")
self.current_md5sum = md5()
# locate the STREAMINFO,
# which is sometimes needed to handle non-subset streams
for (block_id, block_size,
block_reader) in self.metadata_blocks(self.reader):
if (block_id == 0):
# read STREAMINFO
self.minimum_block_size = block_reader.read(16)
self.maximum_block_size = block_reader.read(16)
self.minimum_frame_size = block_reader.read(24)
self.maximum_frame_size = block_reader.read(24)
self.sample_rate = block_reader.read(20)
self.channels = block_reader.read(3) + 1
self.channel_mask = channel_mask
self.bits_per_sample = block_reader.read(5) + 1
self.total_frames = block_reader.read(36)
self.md5sum = block_reader.read_bytes(16)
# these are frame header lookup tables
# which vary slightly depending on STREAMINFO's values
self.BLOCK_SIZE = [
self.maximum_block_size, 192, 576, 1152, 2304, 4608, None,
None, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768
]
self.SAMPLE_RATE = [
self.sample_rate, 88200, 176400, 192000, 8000, 16000,
22050, 24000, 32000, 44100, 48000, 96000, None, None, None,
None
]
self.BITS_PER_SAMPLE = [
self.bits_per_sample, 8, 12, None, 16, 20, 24, None
]
def metadata_blocks(self, reader):
"""yields a (block_id, block_size, block_reader) tuple
per metadata block where block_reader is a BitstreamReader substream"""
(last_block, block_id, block_size) = self.reader.parse("1u 7u 24u")
while (last_block == 0):
yield (block_id, block_size, self.reader.substream(block_size))
(last_block, block_id, block_size) = self.reader.parse("1u 7u 24u")
else:
yield (block_id, block_size, self.reader.substream(block_size))
def read(self, pcm_frames):
# if the stream is exhausted,
# verify its MD5 sum and return an empty pcm.FrameList object
if (self.total_frames < 1):
if (self.md5sum == self.current_md5sum.digest()):
return empty_framelist(self.channels, self.bits_per_sample)
else:
raise ValueError("MD5 checksum mismatch")
crc16 = CRC16()
self.reader.add_callback(crc16.update)
# fetch the decoding parameters from the frame header
(block_size, channel_assignment,
bits_per_sample) = self.read_frame_header()
channel_count = self.CHANNEL_COUNT[channel_assignment]
if (channel_count is None):
raise ValueError("invalid channel assignment")
# channel data will be a list of signed sample lists, one per channel
# such as [[1, 2, 3, ...], [4, 5, 6, ...]] for a 2 channel stream
channel_data = []
for channel_number in range(channel_count):
if ((channel_assignment == 0x8) and (channel_number == 1)):
# for left-difference assignment
# the difference channel has 1 additional bit
channel_data.append(
self.read_subframe(block_size, bits_per_sample + 1))
elif ((channel_assignment == 0x9) and (channel_number == 0)):
# for difference-right assignment
# the difference channel has 1 additional bit
channel_data.append(
self.read_subframe(block_size, bits_per_sample + 1))
elif ((channel_assignment == 0xA) and (channel_number == 1)):
# for average-difference assignment
# the difference channel has 1 additional bit
channel_data.append(
self.read_subframe(block_size, bits_per_sample + 1))
else:
# otherwise, use the frame's bits-per-sample value
channel_data.append(
self.read_subframe(block_size, bits_per_sample))
# one all the subframes have been decoded,
# reconstruct them depending on the channel assignment
if (channel_assignment == 0x8):
# left-difference
samples = []
for (left, difference) in zip(*channel_data):
samples.append(left)
samples.append(left - difference)
elif (channel_assignment == 0x9):
# difference-right
samples = []
for (difference, right) in zip(*channel_data):
samples.append(difference + right)
samples.append(right)
elif (channel_assignment == 0xA):
# mid-side
samples = []
for (mid, side) in zip(*channel_data):
samples.append((((mid * 2) + (side % 2)) + side) // 2)
samples.append((((mid * 2) + (side % 2)) - side) // 2)
else:
# independent
samples = [0] * block_size * channel_count
for (i, channel) in enumerate(channel_data):
samples[i::channel_count] = channel
self.reader.byte_align()
# read and verify the frame's trailing CRC-16 footer
self.reader.read(16)
self.reader.pop_callback()
if (int(crc16) != 0):
raise ValueError("CRC16 mismatch in frame footer")
# deduct the amount of PCM frames from the remaining amount
self.total_frames -= block_size
# build a pcm.FrameList object from the combined samples
framelist = from_list(samples, channel_count, bits_per_sample, True)
# update the running MD5 sum calculation with the frame's data
self.current_md5sum.update(framelist.to_bytes(0, 1))
# and finally return the frame data
return framelist
def read_frame_header(self):
crc8 = CRC8()
self.reader.add_callback(crc8.update)
# read the 32-bit FLAC frame header
sync_code = self.reader.read(14)
if (sync_code != 0x3FFE):
raise ValueError("invalid sync code")
self.reader.skip(1)
blocking_strategy = self.reader.read(1)
block_size_bits = self.reader.read(4)
sample_rate_bits = self.reader.read(4)
channel_assignment = self.reader.read(4)
bits_per_sample_bits = self.reader.read(3)
self.reader.skip(1)
# the frame number is a UTF-8 encoded value
# which takes a variable number of whole bytes
frame_number = self.read_utf8()
# unpack the 4 bit block size field
# which is the total PCM frames in the FLAC frame
# and may require up to 16 more bits if the frame is usually-sized
# (which typically happens at the end of the stream)
if (block_size_bits == 0x6):
block_size = self.reader.read(8) + 1
elif (block_size_bits == 0x7):
block_size = self.reader.read(16) + 1
else:
block_size = self.BLOCK_SIZE[block_size_bits]
# unpack the 4 bit sample rate field
# which is used for playback, but not needed for decoding
# and may require up to 16 more bits
# if the stream has a particularly unusual sample rate
if (sample_rate_bits == 0xC):
sample_rate = self.reader.read(8) * 1000
elif (sample_rate_bits == 0xD):
sample_rate = self.reader.read(16)
elif (sample_rate_bits == 0xE):
sample_rate = self.reader.read(16) * 10
elif (sample_rate_bits == 0xF):
raise ValueError("invalid sample rate")
else:
sample_rate = self.SAMPLE_RATE[sample_rate_bits]
# unpack the 3 bit bits-per-sample field
# this never requires additional bits
if ((bits_per_sample_bits == 0x3) or (bits_per_sample_bits == 0x7)):
raise ValueError("invalid bits per sample")
else:
bits_per_sample = self.BITS_PER_SAMPLE[bits_per_sample_bits]
# read and verify frame's CRC-8 value
self.reader.read(8)
self.reader.pop_callback()
if (int(crc8) != 0):
raise ValueError("CRC8 mismatch in frame header")
return (block_size, channel_assignment, bits_per_sample)
def read_subframe_header(self):
"""returns a tuple of (subframe_type, subframe_order, wasted_bps)"""
self.reader.skip(1)
subframe_type = self.reader.read(6)
if (self.reader.read(1) == 1):
wasted_bps = self.reader.unary(1) + 1
else:
wasted_bps = 0
# extract "order" value from 6 bit subframe type, if necessary
if (subframe_type == 0):
return (self.SUBFRAME_CONSTANT, None, wasted_bps)
elif (subframe_type == 1):
return (self.SUBFRAME_VERBATIM, None, wasted_bps)
elif ((subframe_type & 0x38) == 0x08):
return (self.SUBFRAME_FIXED, subframe_type & 0x07, wasted_bps)
elif ((subframe_type & 0x20) == 0x20):
return (self.SUBFRAME_LPC, (subframe_type & 0x1F) + 1, wasted_bps)
else:
raise ValueError("invalid subframe type")
def read_subframe(self, block_size, bits_per_sample):
(subframe_type, subframe_order,
wasted_bps) = self.read_subframe_header()
# read a list of signed sample values
# depending on the subframe type, block size,
# adjusted bits per sample and optional subframe order
if (subframe_type == self.SUBFRAME_CONSTANT):
subframe_samples = self.read_constant_subframe(
block_size, bits_per_sample - wasted_bps)
elif (subframe_type == self.SUBFRAME_VERBATIM):
subframe_samples = self.read_verbatim_subframe(
block_size, bits_per_sample - wasted_bps)
elif (subframe_type == self.SUBFRAME_FIXED):
subframe_samples = self.read_fixed_subframe(
block_size, bits_per_sample - wasted_bps, subframe_order)
else:
subframe_samples = self.read_lpc_subframe(
block_size, bits_per_sample - wasted_bps, subframe_order)
# account for wasted bits-per-sample, if necessary
if (wasted_bps):
return [sample << wasted_bps for sample in subframe_samples]
else:
return subframe_samples
def read_constant_subframe(self, block_size, bits_per_sample):
sample = self.reader.read_signed(bits_per_sample)
return [sample] * block_size
def read_verbatim_subframe(self, block_size, bits_per_sample):
return [
self.reader.read_signed(bits_per_sample) for x in range(block_size)
]
def read_fixed_subframe(self, block_size, bits_per_sample, order):
# "order" number of warm-up samples
samples = [
self.reader.read_signed(bits_per_sample) for i in range(order)
]
# "block_size" - "order" number of residual values
residuals = self.read_residual(block_size, order)
# which are applied to the warm-up samples
# depending on the FIXED subframe order
# and results in "block_size" number of total samples
if (order == 0):
return residuals
elif (order == 1):
for residual in residuals:
samples.append(samples[-1] + residual)
return samples
elif (order == 2):
for residual in residuals:
samples.append((2 * samples[-1]) - samples[-2] + residual)
return samples
elif (order == 3):
for residual in residuals:
samples.append((3 * samples[-1]) - (3 * samples[-2]) +
samples[-3] + residual)
return samples
elif (order == 4):
for residual in residuals:
samples.append((4 * samples[-1]) - (6 * samples[-2]) +
(4 * samples[-3]) - samples[-4] + residual)
return samples
else:
raise ValueError("unsupported FIXED subframe order")
def read_lpc_subframe(self, block_size, bits_per_sample, order):
# "order" number of warm-up samples
samples = [
self.reader.read_signed(bits_per_sample) for i in range(order)
]
# the size of each QLP coefficient, in bits
qlp_precision = self.reader.read(4)
# the amount of right shift to apply
# during LPC calculation
# (though this is a signed value, negative shifts are noops
# in the reference FLAC decoder)
qlp_shift_needed = max(self.reader.read_signed(5), 0)
# "order" number of signed QLP coefficients
qlp_coeffs = [
self.reader.read_signed(qlp_precision + 1) for i in range(order)
]
# QLP coefficients are applied in reverse order
qlp_coeffs.reverse()
# "block_size" - "order" number of residual values
residuals = self.read_residual(block_size, order)
# which are applied to the running LPC calculation
for residual in residuals:
samples.append((sum([
coeff * sample
for (coeff, sample) in zip(qlp_coeffs, samples[-order:])
]) >> qlp_shift_needed) + residual)
return samples
def read_residual(self, block_size, order):
residuals = []
coding_method = self.reader.read(2)
partition_order = self.reader.read(4)
# each parititon contains block_size / 2 ** partition_order
# number of residuals
for partition_number in range(2**partition_order):
if (partition_number == 0):
# except for the first partition
# which contains "order" less than the rest
residuals.extend(
self.read_residual_partition(
coding_method,
(block_size // 2**partition_order) - order))
else:
residuals.extend(
self.read_residual_partition(
coding_method, block_size // 2**partition_order))
return residuals
def read_residual_partition(self, coding_method, residual_count):
if (coding_method == 0):
# the Rice parameters determines the number of
# least-significant bits to read for each residual
rice_parameter = self.reader.read(4)
if (rice_parameter == 0xF):
escape_code = self.reader.read(5)
return [
self.reader.read_signed(escape_code)
for i in range(residual_count)
]
elif (coding_method == 1):
# 24 bps streams may use a 5-bit Rice parameter
# for better compression
rice_parameter = self.reader.read(5)
if (rice_parameter == 0x1F):
escape_code = self.reader.read(5)
return [
self.reader.read_signed(escape_code)
for i in range(residual_count)
]
else:
raise ValueError("invalid Rice coding parameter")
# a list of signed residual values
partition_residuals = []
for i in range(residual_count):
msb = self.reader.unary(1) # most-significant bits
lsb = self.reader.read(rice_parameter) # least-significant bits
value = (msb << rice_parameter) | lsb # combined into a value
if (value & 1): # whose least-significant bit is the sign value
partition_residuals.append(-(value >> 1) - 1)
else:
partition_residuals.append(value >> 1)
return partition_residuals
def read_utf8(self):
total_bytes = self.reader.unary(0)
value = self.reader.read(7 - total_bytes)
while (total_bytes > 1):
value = ((value << 6) | self.reader.parse("2p 6u")[0])
total_bytes -= 1
return value
def close(self):
self.reader.close()
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
class AuReader(object):
def __init__(self, au_filename):
from audiotools.bitstream import BitstreamReader
from audiotools.text import (ERR_AU_INVALID_HEADER,
ERR_AU_UNSUPPORTED_FORMAT)
self.stream = BitstreamReader(open(au_filename, "rb"), False)
(magic_number, self.data_offset, data_size, encoding_format,
self.sample_rate, self.channels) = self.stream.parse("4b 5* 32u")
if (magic_number != b'.snd'):
self.stream.close()
raise ValueError(ERR_AU_INVALID_HEADER)
try:
self.bits_per_sample = {2: 8, 3: 16, 4: 24}[encoding_format]
except KeyError:
self.stream.close()
raise ValueError(ERR_AU_UNSUPPORTED_FORMAT)
self.channel_mask = {1: 0x4, 2: 0x3}.get(self.channels, 0)
self.bytes_per_pcm_frame = ((self.bits_per_sample // 8) *
self.channels)
self.total_pcm_frames = (data_size // self.bytes_per_pcm_frame)
self.remaining_pcm_frames = self.total_pcm_frames
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
def read(self, pcm_frames):
# try to read requested PCM frames or remaining frames
requested_pcm_frames = min(max(pcm_frames, 1),
self.remaining_pcm_frames)
requested_bytes = (self.bytes_per_pcm_frame * requested_pcm_frames)
pcm_data = self.stream.read_bytes(requested_bytes)
# raise exception if data block exhausted early
if (len(pcm_data) < requested_bytes):
from audiotools.text import ERR_AU_TRUNCATED_DATA
raise IOError(ERR_AU_TRUNCATED_DATA)
else:
self.remaining_pcm_frames -= requested_pcm_frames
# return parsed chunk
return FrameList(pcm_data, self.channels, self.bits_per_sample,
True, True)
def read_closed(self, pcm_frames):
raise ValueError("cannot read closed stream")
def seek(self, pcm_frame_offset):
if (pcm_frame_offset < 0):
from audiotools.text import ERR_NEGATIVE_SEEK
raise ValueError(ERR_NEGATIVE_SEEK)
# ensure one doesn't walk off the end of the file
pcm_frame_offset = min(pcm_frame_offset, self.total_pcm_frames)
# position file in data block
self.stream.seek(
self.data_offset + (pcm_frame_offset * self.bytes_per_pcm_frame),
0)
self.remaining_pcm_frames = (self.total_pcm_frames - pcm_frame_offset)
return pcm_frame_offset
def seek_closed(self, pcm_frame_offset):
raise ValueError("cannot seek closed stream")
def close(self):
self.stream.close()
self.read = self.read_closed
self.seek = self.seek_closed
class AiffReader(object):
"""a PCMReader object for reading AIFF file contents"""
def __init__(self, aiff_filename):
"""aiff_filename is a string"""
from audiotools.bitstream import BitstreamReader
self.stream = BitstreamReader(open(aiff_filename, "rb"), False)
# ensure FORM<size>AIFF header is ok
try:
(form, total_size, aiff) = self.stream.parse("4b 32u 4b")
except struct.error:
from audiotools.text import ERR_AIFF_INVALID_AIFF
raise InvalidAIFF(ERR_AIFF_INVALID_AIFF)
if form != b'FORM':
from audiotools.text import ERR_AIFF_NOT_AIFF
raise ValueError(ERR_AIFF_NOT_AIFF)
elif aiff != b'AIFF':
from audiotools.text import ERR_AIFF_INVALID_AIFF
raise ValueError(ERR_AIFF_INVALID_AIFF)
else:
total_size -= 4
comm_chunk_read = False
# walk through chunks until "SSND" chunk encountered
while total_size > 0:
try:
(chunk_id, chunk_size) = self.stream.parse("4b 32u")
except struct.error:
from audiotools.text import ERR_AIFF_INVALID_AIFF
raise ValueError(ERR_AIFF_INVALID_AIFF)
if not frozenset(chunk_id).issubset(AiffAudio.PRINTABLE_ASCII):
from audiotools.text import ERR_AIFF_INVALID_CHUNK_ID
raise ValueError(ERR_AIFF_INVALID_CHUNK_ID)
else:
total_size -= 8
if chunk_id == b"COMM":
# when "COMM" chunk encountered,
# use it to populate PCMReader attributes
(self.channels, self.total_pcm_frames, self.bits_per_sample,
self.sample_rate, channel_mask) = parse_comm(self.stream)
self.channel_mask = int(channel_mask)
self.bytes_per_pcm_frame = ((self.bits_per_sample // 8) *
self.channels)
self.remaining_pcm_frames = self.total_pcm_frames
comm_chunk_read = True
elif chunk_id == b"SSND":
# when "SSND" chunk encountered,
# strip off the "offset" and "block_size" attributes
# and ready PCMReader for reading
if not comm_chunk_read:
from audiotools.text import ERR_AIFF_PREMATURE_SSND_CHUNK
raise ValueError(ERR_AIFF_PREMATURE_SSND_CHUNK)
else:
self.stream.skip_bytes(8)
self.ssnd_start = self.stream.getpos()
return
else:
# all other chunks are ignored
self.stream.skip_bytes(chunk_size)
if chunk_size % 2:
if len(self.stream.read_bytes(1)) < 1:
from audiotools.text import ERR_AIFF_INVALID_CHUNK
raise ValueError(ERR_AIFF_INVALID_CHUNK)
total_size -= (chunk_size + 1)
else:
total_size -= chunk_size
else:
# raise an error if no "SSND" chunk is encountered
from audiotools.text import ERR_AIFF_NO_SSND_CHUNK
raise ValueError(ERR_AIFF_NO_SSND_CHUNK)
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
def read(self, pcm_frames):
"""try to read a pcm.FrameList with the given number of PCM frames"""
# try to read requested PCM frames or remaining frames
requested_pcm_frames = min(max(pcm_frames, 1),
self.remaining_pcm_frames)
requested_bytes = (self.bytes_per_pcm_frame * requested_pcm_frames)
pcm_data = self.stream.read_bytes(requested_bytes)
# raise exception if "SSND" chunk exhausted early
if len(pcm_data) < requested_bytes:
from audiotools.text import ERR_AIFF_TRUNCATED_SSND_CHUNK
raise IOError(ERR_AIFF_TRUNCATED_SSND_CHUNK)
else:
self.remaining_pcm_frames -= requested_pcm_frames
# return parsed chunk
return FrameList(pcm_data, self.channels, self.bits_per_sample,
True, True)
def read_closed(self, pcm_frames):
raise ValueError("cannot read closed stream")
def seek(self, pcm_frame_offset):
"""tries to seek to the given PCM frame offset
returns the total amount of frames actually seeked over"""
if pcm_frame_offset < 0:
from audiotools.text import ERR_NEGATIVE_SEEK
raise ValueError(ERR_NEGATIVE_SEEK)
# ensure one doesn't walk off the end of the file
pcm_frame_offset = min(pcm_frame_offset, self.total_pcm_frames)
# position file in "SSND" chunk
self.stream.setpos(self.ssnd_start)
self.stream.seek((pcm_frame_offset * self.bytes_per_pcm_frame), 1)
self.remaining_pcm_frames = (self.total_pcm_frames - pcm_frame_offset)
return pcm_frame_offset
def seek_closed(self, pcm_frame_offset):
raise ValueError("cannot seek closed stream")
def close(self):
"""closes the stream for reading"""
self.stream.close()
self.read = self.read_closed
self.seek = self.seek_closed
class AiffReader(object):
"""a PCMReader object for reading AIFF file contents"""
def __init__(self, aiff_filename):
"""aiff_filename is a string"""
from audiotools.bitstream import BitstreamReader
self.stream = BitstreamReader(open(aiff_filename, "rb"), False)
# ensure FORM<size>AIFF header is ok
try:
(form,
total_size,
aiff) = self.stream.parse("4b 32u 4b")
except struct.error:
from audiotools.text import ERR_AIFF_INVALID_AIFF
raise InvalidAIFF(ERR_AIFF_INVALID_AIFF)
if form != b'FORM':
from audiotools.text import ERR_AIFF_NOT_AIFF
raise ValueError(ERR_AIFF_NOT_AIFF)
elif aiff != b'AIFF':
from audiotools.text import ERR_AIFF_INVALID_AIFF
raise ValueError(ERR_AIFF_INVALID_AIFF)
else:
total_size -= 4
comm_chunk_read = False
# walk through chunks until "SSND" chunk encountered
while total_size > 0:
try:
(chunk_id,
chunk_size) = self.stream.parse("4b 32u")
except struct.error:
from audiotools.text import ERR_AIFF_INVALID_AIFF
raise ValueError(ERR_AIFF_INVALID_AIFF)
if not frozenset(chunk_id).issubset(AiffAudio.PRINTABLE_ASCII):
from audiotools.text import ERR_AIFF_INVALID_CHUNK_ID
raise ValueError(ERR_AIFF_INVALID_CHUNK_ID)
else:
total_size -= 8
if chunk_id == b"COMM":
# when "COMM" chunk encountered,
# use it to populate PCMReader attributes
(self.channels,
self.total_pcm_frames,
self.bits_per_sample,
self.sample_rate,
channel_mask) = parse_comm(self.stream)
self.channel_mask = int(channel_mask)
self.bytes_per_pcm_frame = ((self.bits_per_sample // 8) *
self.channels)
self.remaining_pcm_frames = self.total_pcm_frames
comm_chunk_read = True
elif chunk_id == b"SSND":
# when "SSND" chunk encountered,
# strip off the "offset" and "block_size" attributes
# and ready PCMReader for reading
if not comm_chunk_read:
from audiotools.text import ERR_AIFF_PREMATURE_SSND_CHUNK
raise ValueError(ERR_AIFF_PREMATURE_SSND_CHUNK)
else:
self.stream.skip_bytes(8)
self.ssnd_start = self.stream.getpos()
return
else:
# all other chunks are ignored
self.stream.skip_bytes(chunk_size)
if chunk_size % 2:
if len(self.stream.read_bytes(1)) < 1:
from audiotools.text import ERR_AIFF_INVALID_CHUNK
raise ValueError(ERR_AIFF_INVALID_CHUNK)
total_size -= (chunk_size + 1)
else:
total_size -= chunk_size
else:
# raise an error if no "SSND" chunk is encountered
from audiotools.text import ERR_AIFF_NO_SSND_CHUNK
raise ValueError(ERR_AIFF_NO_SSND_CHUNK)
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
def read(self, pcm_frames):
"""try to read a pcm.FrameList with the given number of PCM frames"""
# try to read requested PCM frames or remaining frames
requested_pcm_frames = min(max(pcm_frames, 1),
self.remaining_pcm_frames)
requested_bytes = (self.bytes_per_pcm_frame *
requested_pcm_frames)
pcm_data = self.stream.read_bytes(requested_bytes)
# raise exception if "SSND" chunk exhausted early
if len(pcm_data) < requested_bytes:
from audiotools.text import ERR_AIFF_TRUNCATED_SSND_CHUNK
raise IOError(ERR_AIFF_TRUNCATED_SSND_CHUNK)
else:
self.remaining_pcm_frames -= requested_pcm_frames
# return parsed chunk
return FrameList(pcm_data,
self.channels,
self.bits_per_sample,
True,
True)
def read_closed(self, pcm_frames):
raise ValueError("cannot read closed stream")
def seek(self, pcm_frame_offset):
"""tries to seek to the given PCM frame offset
returns the total amount of frames actually seeked over"""
if pcm_frame_offset < 0:
from audiotools.text import ERR_NEGATIVE_SEEK
raise ValueError(ERR_NEGATIVE_SEEK)
# ensure one doesn't walk off the end of the file
pcm_frame_offset = min(pcm_frame_offset,
self.total_pcm_frames)
# position file in "SSND" chunk
self.stream.setpos(self.ssnd_start)
self.stream.seek((pcm_frame_offset * self.bytes_per_pcm_frame), 1)
self.remaining_pcm_frames = (self.total_pcm_frames -
pcm_frame_offset)
return pcm_frame_offset
def seek_closed(self, pcm_frame_offset):
raise ValueError("cannot seek closed stream")
def close(self):
"""closes the stream for reading"""
self.stream.close()
self.read = self.read_closed
self.seek = self.seek_closed
def wave_header_footer(self):
"""returns a pair of data strings before and after PCM data
the first contains all data before the PCM content of the data chunk
the second containing all data after the data chunk
for example:
>>> w = audiotools.open("input.wav")
>>> (head, tail) = w.wave_header_footer()
>>> f = open("output.wav", "wb")
>>> f.write(head)
>>> audiotools.transfer_framelist_data(w.to_pcm(), f.write)
>>> f.write(tail)
>>> f.close()
should result in "output.wav" being identical to "input.wav"
"""
from audiotools.bitstream import BitstreamReader
from audiotools.bitstream import BitstreamRecorder
head = BitstreamRecorder(1)
tail = BitstreamRecorder(1)
current_block = head
fmt_found = False
wave_file = BitstreamReader(open(self.filename, 'rb'), 1)
try:
# transfer the 12-byte "RIFFsizeWAVE" header to head
(riff, size, wave) = wave_file.parse("4b 32u 4b")
if (riff != 'RIFF'):
from audiotools.text import ERR_WAV_NOT_WAVE
raise ValueError(ERR_WAV_NOT_WAVE)
elif (wave != 'WAVE'):
from audiotools.text import ERR_WAV_INVALID_WAVE
raise ValueError(ERR_WAV_INVALID_WAVE)
else:
current_block.build("4b 32u 4b", (riff, size, wave))
total_size = size - 4
while (total_size > 0):
# transfer each chunk header
(chunk_id, chunk_size) = wave_file.parse("4b 32u")
if (not frozenset(chunk_id).issubset(self.PRINTABLE_ASCII)):
from audiotools.text import ERR_WAV_INVALID_CHUNK
raise ValueError(ERR_WAV_INVALID_CHUNK)
else:
current_block.build("4b 32u", (chunk_id, chunk_size))
total_size -= 8
# and transfer the full content of non-audio chunks
if (chunk_id != "data"):
if (chunk_id == "fmt "):
if (not fmt_found):
fmt_found = True
else:
from audiotools.text import ERR_WAV_MULTIPLE_FMT
raise ValueError(ERR_WAV_MULTIPLE_FMT)
if (chunk_size % 2):
current_block.write_bytes(
wave_file.read_bytes(chunk_size + 1))
total_size -= (chunk_size + 1)
else:
current_block.write_bytes(
wave_file.read_bytes(chunk_size))
total_size -= chunk_size
else:
wave_file.skip_bytes(chunk_size)
current_block = tail
if (chunk_size % 2):
current_block.write_bytes(wave_file.read_bytes(1))
total_size -= (chunk_size + 1)
else:
total_size -= chunk_size
if (fmt_found):
return (head.data(), tail.data())
else:
from audiotools.text import ERR_WAV_NO_FMT_CHUNK
return ValueError(ERR_WAV_NO_FMT_CHUNK)
finally:
wave_file.close()
class AuReader(object):
def __init__(self, au_filename):
from audiotools.bitstream import BitstreamReader
from audiotools.text import (ERR_AU_INVALID_HEADER,
ERR_AU_UNSUPPORTED_FORMAT)
self.stream = BitstreamReader(open(au_filename, "rb"), False)
(magic_number,
self.data_offset,
data_size,
encoding_format,
self.sample_rate,
self.channels) = self.stream.parse("4b 5* 32u")
if magic_number != b'.snd':
self.stream.close()
raise ValueError(ERR_AU_INVALID_HEADER)
try:
self.bits_per_sample = {2: 8, 3: 16, 4: 24}[encoding_format]
except KeyError:
self.stream.close()
raise ValueError(ERR_AU_UNSUPPORTED_FORMAT)
self.channel_mask = {1: 0x4, 2: 0x3}.get(self.channels, 0)
self.bytes_per_pcm_frame = ((self.bits_per_sample // 8) *
self.channels)
self.total_pcm_frames = (data_size // self.bytes_per_pcm_frame)
self.remaining_pcm_frames = self.total_pcm_frames
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
def read(self, pcm_frames):
# try to read requested PCM frames or remaining frames
requested_pcm_frames = min(max(pcm_frames, 1),
self.remaining_pcm_frames)
requested_bytes = (self.bytes_per_pcm_frame *
requested_pcm_frames)
pcm_data = self.stream.read_bytes(requested_bytes)
# raise exception if data block exhausted early
if len(pcm_data) < requested_bytes:
from audiotools.text import ERR_AU_TRUNCATED_DATA
raise IOError(ERR_AU_TRUNCATED_DATA)
else:
self.remaining_pcm_frames -= requested_pcm_frames
# return parsed chunk
return FrameList(pcm_data,
self.channels,
self.bits_per_sample,
True,
True)
def read_closed(self, pcm_frames):
raise ValueError("cannot read closed stream")
def seek(self, pcm_frame_offset):
if pcm_frame_offset < 0:
from audiotools.text import ERR_NEGATIVE_SEEK
raise ValueError(ERR_NEGATIVE_SEEK)
# ensure one doesn't walk off the end of the file
pcm_frame_offset = min(pcm_frame_offset,
self.total_pcm_frames)
# position file in data block
self.stream.seek(self.data_offset +
(pcm_frame_offset *
self.bytes_per_pcm_frame), 0)
self.remaining_pcm_frames = (self.total_pcm_frames -
pcm_frame_offset)
return pcm_frame_offset
def seek_closed(self, pcm_frame_offset):
raise ValueError("cannot seek closed stream")
def close(self):
self.stream.close()
self.read = self.read_closed
self.seek = self.seek_closed
class FlacDecoder:
CHANNEL_COUNT = [1, 2, 3, 4, 5, 6, 7, 8, 2, 2, 2,
None, None, None, None, None]
(SUBFRAME_CONSTANT,
SUBFRAME_VERBATIM,
SUBFRAME_FIXED,
SUBFRAME_LPC) = range(4)
def __init__(self, filename, channel_mask):
self.reader = BitstreamReader(open(filename, "rb"), 0)
if (self.reader.read_bytes(4) != 'fLaC'):
raise ValueError("invalid FLAC file")
self.current_md5sum = md5()
#locate the STREAMINFO,
#which is sometimes needed to handle non-subset streams
for (block_id,
block_size,
block_reader) in self.metadata_blocks(self.reader):
if (block_id == 0):
#read STREAMINFO
self.minimum_block_size = block_reader.read(16)
self.maximum_block_size = block_reader.read(16)
self.minimum_frame_size = block_reader.read(24)
self.maximum_frame_size = block_reader.read(24)
self.sample_rate = block_reader.read(20)
self.channels = block_reader.read(3) + 1
self.channel_mask = channel_mask
self.bits_per_sample = block_reader.read(5) + 1
self.total_frames = block_reader.read64(36)
self.md5sum = block_reader.read_bytes(16)
#these are frame header lookup tables
#which vary slightly depending on STREAMINFO's values
self.BLOCK_SIZE = [self.maximum_block_size,
192, 576, 1152,
2304, 4608, None, None,
256, 512, 1024, 2048,
4096, 8192, 16384, 32768]
self.SAMPLE_RATE = [self.sample_rate,
88200, 176400, 192000,
8000, 16000, 22050, 24000,
32000, 44100, 48000, 96000,
None, None, None, None]
self.BITS_PER_SAMPLE = [self.bits_per_sample,
8, 12, None, 16, 20, 24, None]
def metadata_blocks(self, reader):
"""yields a (block_id, block_size, block_reader) tuple
per metadata block where block_reader is a BitstreamReader substream"""
(last_block, block_id, block_size) = self.reader.parse("1u 7u 24u")
while (last_block == 0):
yield (block_id, block_size, self.reader.substream(block_size))
(last_block, block_id, block_size) = self.reader.parse("1u 7u 24u")
else:
yield (block_id, block_size, self.reader.substream(block_size))
def read(self, pcm_frames):
#if the stream is exhausted,
#verify its MD5 sum and return an empty pcm.FrameList object
if (self.total_frames < 1):
if (self.md5sum == self.current_md5sum.digest()):
return from_list([], self.channels, self.bits_per_sample, True)
else:
raise ValueError("MD5 checksum mismatch")
crc16 = CRC16()
self.reader.add_callback(crc16.update)
#fetch the decoding parameters from the frame header
(block_size,
channel_assignment,
bits_per_sample) = self.read_frame_header()
channel_count = self.CHANNEL_COUNT[channel_assignment]
if (channel_count is None):
raise ValueError("invalid channel assignment")
#channel data will be a list of signed sample lists, one per channel
#such as [[1, 2, 3, ...], [4, 5, 6, ...]] for a 2 channel stream
channel_data = []
for channel_number in xrange(channel_count):
if ((channel_assignment == 0x8) and (channel_number == 1)):
#for left-difference assignment
#the difference channel has 1 additional bit
channel_data.append(self.read_subframe(block_size,
bits_per_sample + 1))
elif ((channel_assignment == 0x9) and (channel_number == 0)):
#for difference-right assignment
#the difference channel has 1 additional bit
channel_data.append(self.read_subframe(block_size,
bits_per_sample + 1))
elif ((channel_assignment == 0xA) and (channel_number == 1)):
#for mid-side assignment
#the side channel has 1 additional bit
channel_data.append(self.read_subframe(block_size,
bits_per_sample + 1))
else:
#otherwise, use the frame's bits-per-sample value
channel_data.append(self.read_subframe(block_size,
bits_per_sample))
#one all the subframes have been decoded,
#reconstruct them depending on the channel assignment
if (channel_assignment == 0x8):
#left-difference
samples = []
for (left, difference) in zip(*channel_data):
samples.append(left)
samples.append(left - difference)
elif (channel_assignment == 0x9):
#difference-right
samples = []
for (difference, right) in zip(*channel_data):
samples.append(difference + right)
samples.append(right)
elif (channel_assignment == 0xA):
#mid-side
samples = []
for (mid, side) in zip(*channel_data):
samples.append((((mid * 2) + (side % 2)) + side) / 2)
samples.append((((mid * 2) + (side % 2)) - side) / 2)
else:
#independent
samples = [0] * block_size * channel_count
for (i, channel) in enumerate(channel_data):
samples[i::channel_count] = channel
self.reader.byte_align()
#read and verify the frame's trailing CRC-16 footer
self.reader.read(16)
self.reader.pop_callback()
if (int(crc16) != 0):
raise ValueError("CRC16 mismatch in frame footer")
#deduct the amount of PCM frames from the remaining amount
self.total_frames -= block_size
#build a pcm.FrameList object from the combined samples
framelist = from_list(samples, channel_count, bits_per_sample, True)
#update the running MD5 sum calculation with the frame's data
self.current_md5sum.update(framelist.to_bytes(0, 1))
#and finally return the frame data
return framelist
def read_frame_header(self):
crc8 = CRC8()
self.reader.add_callback(crc8.update)
#read the 32-bit FLAC frame header
sync_code = self.reader.read(14)
if (sync_code != 0x3FFE):
raise ValueError("invalid sync code")
self.reader.skip(1)
blocking_strategy = self.reader.read(1)
block_size_bits = self.reader.read(4)
sample_rate_bits = self.reader.read(4)
channel_assignment = self.reader.read(4)
bits_per_sample_bits = self.reader.read(3)
self.reader.skip(1)
#the frame number is a UTF-8 encoded value
#which takes a variable number of whole bytes
frame_number = self.read_utf8()
#unpack the 4 bit block size field
#which is the total PCM frames in the FLAC frame
#and may require up to 16 more bits if the frame is usually-sized
#(which typically happens at the end of the stream)
if (block_size_bits == 0x6):
block_size = self.reader.read(8) + 1
elif (block_size_bits == 0x7):
block_size = self.reader.read(16) + 1
else:
block_size = self.BLOCK_SIZE[block_size_bits]
#unpack the 4 bit sample rate field
#which is used for playback, but not needed for decoding
#and may require up to 16 more bits
#if the stream has a particularly unusual sample rate
if (sample_rate_bits == 0xC):
sample_rate = self.reader.read(8) * 1000
elif (sample_rate_bits == 0xD):
sample_rate = self.reader.read(16)
elif (sample_rate_bits == 0xE):
sample_rate = self.reader.read(16) * 10
elif (sample_rate_bits == 0xF):
raise ValueError("invalid sample rate")
else:
sample_rate = self.SAMPLE_RATE[sample_rate_bits]
#unpack the 3 bit bits-per-sample field
#this never requires additional bits
if ((bits_per_sample_bits == 0x3) or (bits_per_sample_bits == 0x7)):
raise ValueError("invalid bits per sample")
else:
bits_per_sample = self.BITS_PER_SAMPLE[bits_per_sample_bits]
#read and verify frame's CRC-8 value
self.reader.read(8)
self.reader.pop_callback()
if (int(crc8) != 0):
raise ValueError("CRC8 mismatch in frame header")
return (block_size, channel_assignment, bits_per_sample)
def read_subframe_header(self):
"""returns a tuple of (subframe_type, subframe_order, wasted_bps)"""
self.reader.skip(1)
subframe_type = self.reader.read(6)
if (self.reader.read(1) == 1):
wasted_bps = self.reader.unary(1) + 1
else:
wasted_bps = 0
#extract "order" value from 6 bit subframe type, if necessary
if (subframe_type == 0):
return (self.SUBFRAME_CONSTANT, None, wasted_bps)
elif (subframe_type == 1):
return (self.SUBFRAME_VERBATIM, None, wasted_bps)
elif ((subframe_type & 0x38) == 0x08):
return (self.SUBFRAME_FIXED, subframe_type & 0x07, wasted_bps)
elif ((subframe_type & 0x20) == 0x20):
return (self.SUBFRAME_LPC, (subframe_type & 0x1F) + 1, wasted_bps)
else:
raise ValueError("invalid subframe type")
def read_subframe(self, block_size, bits_per_sample):
(subframe_type,
subframe_order,
wasted_bps) = self.read_subframe_header()
#read a list of signed sample values
#depending on the subframe type, block size,
#adjusted bits per sample and optional subframe order
if (subframe_type == self.SUBFRAME_CONSTANT):
subframe_samples = self.read_constant_subframe(
block_size, bits_per_sample - wasted_bps)
elif (subframe_type == self.SUBFRAME_VERBATIM):
subframe_samples = self.read_verbatim_subframe(
block_size, bits_per_sample - wasted_bps)
elif (subframe_type == self.SUBFRAME_FIXED):
subframe_samples = self.read_fixed_subframe(
block_size, bits_per_sample - wasted_bps, subframe_order)
else:
subframe_samples = self.read_lpc_subframe(
block_size, bits_per_sample - wasted_bps, subframe_order)
#account for wasted bits-per-sample, if necessary
if (wasted_bps):
return [sample << wasted_bps for sample in subframe_samples]
else:
return subframe_samples
def read_constant_subframe(self, block_size, bits_per_sample):
sample = self.reader.read_signed(bits_per_sample)
return [sample] * block_size
def read_verbatim_subframe(self, block_size, bits_per_sample):
return [self.reader.read_signed(bits_per_sample)
for x in xrange(block_size)]
def read_fixed_subframe(self, block_size, bits_per_sample, order):
#"order" number of warm-up samples
samples = [self.reader.read_signed(bits_per_sample)
for i in xrange(order)]
#"block_size" - "order" number of residual values
residuals = self.read_residual(block_size, order)
#which are applied to the warm-up samples
#depending on the FIXED subframe order
#and results in "block_size" number of total samples
if (order == 0):
return residuals
elif (order == 1):
for residual in residuals:
samples.append(
samples[-1] +
residual)
return samples
elif (order == 2):
for residual in residuals:
samples.append(
(2 * samples[-1]) -
samples[-2] +
residual)
return samples
elif (order == 3):
for residual in residuals:
samples.append(
(3 * samples[-1]) -
(3 * samples[-2]) +
samples[-3] +
residual)
return samples
elif (order == 4):
for residual in residuals:
samples.append(
(4 * samples[-1]) -
(6 * samples[-2]) +
(4 * samples[-3]) -
samples[-4] +
residual)
return samples
else:
raise ValueError("unsupported FIXED subframe order")
def read_lpc_subframe(self, block_size, bits_per_sample, order):
#"order" number of warm-up samples
samples = [self.reader.read_signed(bits_per_sample)
for i in xrange(order)]
#the size of each QLP coefficient, in bits
qlp_precision = self.reader.read(4)
#the amount of right shift to apply
#during LPC calculation
#(though this is a signed value, negative shifts are noops
# in the reference FLAC decoder)
qlp_shift_needed = max(self.reader.read_signed(5), 0)
#"order" number of signed QLP coefficients
qlp_coeffs = [self.reader.read_signed(qlp_precision + 1)
for i in xrange(order)]
#QLP coefficients are applied in reverse order
qlp_coeffs.reverse()
#"block_size" - "order" number of residual values
residuals = self.read_residual(block_size, order)
#which are applied to the running LPC calculation
for residual in residuals:
samples.append((sum([coeff * sample for (coeff, sample) in
zip(qlp_coeffs, samples[-order:])]) >>
qlp_shift_needed) + residual)
return samples
def read_residual(self, block_size, order):
residuals = []
coding_method = self.reader.read(2)
partition_order = self.reader.read(4)
#each parititon contains block_size / 2 ** partition_order
#number of residuals
for partition_number in xrange(2 ** partition_order):
if (partition_number == 0):
#except for the first partition
#which contains "order" less than the rest
residuals.extend(
self.read_residual_partition(
coding_method,
(block_size / 2 ** partition_order) - order))
else:
residuals.extend(
self.read_residual_partition(
coding_method,
block_size / 2 ** partition_order))
return residuals
def read_residual_partition(self, coding_method, residual_count):
if (coding_method == 0):
#the Rice parameters determines the number of
#least-significant bits to read for each residual
rice_parameter = self.reader.read(4)
if (rice_parameter == 0xF):
escape_code = self.reader.read(5)
return [self.reader.read_signed(escape_code)
for i in xrange(residual_count)]
elif (coding_method == 1):
#24 bps streams may use a 5-bit Rice parameter
#for better compression
rice_parameter = self.reader.read(5)
if (rice_parameter == 0x1F):
escape_code = self.reader.read(5)
return [self.reader.read_signed(escape_code)
for i in xrange(residual_count)]
else:
raise ValueError("invalid Rice coding parameter")
#a list of signed residual values
partition_residuals = []
for i in xrange(residual_count):
msb = self.reader.unary(1) # most-significant bits
lsb = self.reader.read(rice_parameter) # least-significant bits
value = (msb << rice_parameter) | lsb # combined into a value
if (value & 1): # whose least-significant bit is the sign value
partition_residuals.append(-(value >> 1) - 1)
else:
partition_residuals.append(value >> 1)
return partition_residuals
def read_utf8(self):
total_bytes = self.reader.unary(0)
value = self.reader.read(7 - total_bytes)
while (total_bytes > 1):
value = ((value << 6) | self.reader.parse("2p 6u")[0])
total_bytes -= 1
return value
def close(self):
self.reader.close()
def __read_info__(self):
from audiotools.bitstream import BitstreamReader
from audiotools import ChannelMask
reader = BitstreamReader(open(self.filename, "rb"), 1)
reader.mark()
try:
(block_id,
total_samples,
bits_per_sample,
mono_output,
initial_block,
final_block,
sample_rate) = reader.parse(
"4b 64p 32u 64p 2u 1u 8p 1u 1u 5p 5p 4u 37p")
if (block_id != 'wvpk'):
from audiotools.text import ERR_WAVPACK_INVALID_HEADER
raise InvalidWavPack(ERR_WAVPACK_INVALID_HEADER)
if (sample_rate != 0xF):
self.__samplerate__ = WavPackAudio.SAMPLING_RATE[sample_rate]
else:
# if unknown, pull from SAMPLE_RATE sub-block
for (block_id,
nondecoder,
data_size,
data) in self.sub_blocks(reader):
if ((block_id == 0x7) and nondecoder):
self.__samplerate__ = data.read(data_size * 8)
break
else:
# no SAMPLE RATE sub-block found
# so pull info from FMT chunk
reader.rewind()
(self.__samplerate__,) = self.fmt_chunk(reader).parse(
"32p 32u")
self.__bitspersample__ = [8, 16, 24, 32][bits_per_sample]
self.__total_frames__ = total_samples
if (initial_block and final_block):
if (mono_output):
self.__channels__ = 1
self.__channel_mask__ = ChannelMask(0x4)
else:
self.__channels__ = 2
self.__channel_mask__ = ChannelMask(0x3)
else:
# if not mono or stereo, pull from CHANNEL INFO sub-block
reader.rewind()
for (block_id,
nondecoder,
data_size,
data) in self.sub_blocks(reader):
if ((block_id == 0xD) and not nondecoder):
self.__channels__ = data.read(8)
self.__channel_mask__ = ChannelMask(
data.read((data_size - 1) * 8))
break
else:
# no CHANNEL INFO sub-block found
# so pull info from FMT chunk
reader.rewind()
fmt = self.fmt_chunk(reader)
compression_code = fmt.read(16)
self.__channels__ = fmt.read(16)
if (compression_code == 1):
# this is theoretically possible
# with very old .wav files,
# but shouldn't happen in practice
self.__channel_mask__ = \
{1: ChannelMask.from_fields(front_center=True),
2: ChannelMask.from_fields(front_left=True,
front_right=True),
3: ChannelMask.from_fields(front_left=True,
front_right=True,
front_center=True),
4: ChannelMask.from_fields(front_left=True,
front_right=True,
back_left=True,
back_right=True),
5: ChannelMask.from_fields(front_left=True,
front_right=True,
back_left=True,
back_right=True,
front_center=True),
6: ChannelMask.from_fields(front_left=True,
front_right=True,
back_left=True,
back_right=True,
front_center=True,
low_frequency=True)
}.get(self.__channels__, ChannelMask(0))
elif (compression_code == 0xFFFE):
fmt.skip(128)
mask = fmt.read(32)
self.__channel_mask__ = ChannelMask(mask)
else:
from audiotools.text import ERR_WAVPACK_UNSUPPORTED_FMT
raise InvalidWavPack(ERR_WAVPACK_UNSUPPORTED_FMT)
finally:
reader.unmark()
reader.close()
def __init__(self, filename):
"""filename is a plain string"""
from audiotools.bitstream import BitstreamReader
from audiotools import ChannelMask
from io import BytesIO
def read_unsigned(r, c):
MSB = r.unary(1)
LSB = r.read(c)
return MSB * 2 ** c + LSB
def read_long(r):
return read_unsigned(r, read_unsigned(r, 2))
WaveContainer.__init__(self, filename)
try:
reader = BitstreamReader(open(filename, "rb"), False)
except IOError as msg:
raise InvalidShorten(str(msg))
try:
if reader.parse("4b 8u") != [b"ajkg", 2]:
raise InvalidShorten("invalid Shorten header")
# populate channels and bits_per_sample from Shorten header
(file_type,
self.__channels__,
block_length,
max_LPC,
number_of_means,
bytes_to_skip) = [read_long(reader) for i in range(6)]
if (1 <= file_type) and (file_type <= 2):
self.__bits_per_sample__ = 8
elif (3 <= file_type) and (file_type <= 6):
self.__bits_per_sample__ = 16
else:
# FIXME
raise InvalidShorten("unsupported Shorten file type")
# setup some default dummy metadata
self.__sample_rate__ = 44100
if self.__channels__ == 1:
self.__channel_mask__ = ChannelMask(0x4)
elif self.__channels__ == 2:
self.__channel_mask__ = ChannelMask(0x3)
else:
self.__channel_mask__ = ChannelMask(0)
self.__total_frames__ = 0
# populate sample_rate and total_frames
# from first VERBATIM command
command = read_unsigned(reader, 2)
if command == 9:
if sys.version_info[0] >= 3:
verbatim_bytes = \
bytes([read_unsigned(reader, 8) & 0xFF
for i in range(read_unsigned(reader, 5))])
else:
verbatim_bytes = \
b"".join([chr(read_unsigned(reader, 8) & 0xFF)
for i in range(read_unsigned(reader, 5))])
try:
wave = BitstreamReader(BytesIO(verbatim_bytes), True)
header = wave.read_bytes(12)
if (header.startswith(b"RIFF") and
header.endswith(b"WAVE")):
# got RIFF/WAVE header,
# so parse wave blocks as needed
total_size = len(verbatim_bytes) - 12
while total_size >= 8:
(chunk_id, chunk_size) = wave.parse("4b 32u")
total_size -= 8
if chunk_id == b'fmt ':
from audiotools.wav import parse_fmt
(channels,
self.__sample_rate__,
bits_per_sample,
self.__channel_mask__) = parse_fmt(
wave.substream(chunk_size))
elif chunk_id == b'data':
self.__total_frames__ = \
(chunk_size //
(self.__channels__ *
(self.__bits_per_sample__ // 8)))
else:
if chunk_size % 2:
wave.read_bytes(chunk_size + 1)
total_size -= (chunk_size + 1)
else:
wave.read_bytes(chunk_size)
total_size -= chunk_size
except (IOError, ValueError):
pass
try:
aiff = BitstreamReader(BytesIO(verbatim_bytes), False)
header = aiff.read_bytes(12)
if (header.startswith(b"FORM") and
header.endswith(b"AIFF")):
# got FORM/AIFF header
# so parse aiff blocks as needed
total_size = len(verbatim_bytes) - 12
while total_size >= 8:
(chunk_id, chunk_size) = aiff.parse("4b 32u")
total_size -= 8
if chunk_id == b'COMM':
from audiotools.aiff import parse_comm
(channels,
total_sample_frames,
bits_per_sample,
self.__sample_rate__,
self.__channel_mask__) = parse_comm(
aiff.substream(chunk_size))
elif chunk_id == b'SSND':
# subtract 8 bytes for
# "offset" and "block size"
self.__total_frames__ = \
((chunk_size - 8) //
(self.__channels__ *
(self.__bits_per_sample__ // 8)))
else:
if chunk_size % 2:
aiff.read_bytes(chunk_size + 1)
total_size -= (chunk_size + 1)
else:
aiff.read_bytes(chunk_size)
total_size -= chunk_size
except IOError:
pass
except IOError as msg:
raise InvalidShorten(str(msg))
finally:
reader.close()
class WaveReader(object):
"""a PCMReader object for reading wave file contents"""
def __init__(self, wave_filename):
"""wave_filename is a string"""
from audiotools.bitstream import BitstreamReader
self.stream = BitstreamReader(open(wave_filename, "rb"), True)
# ensure RIFF<size>WAVE header is ok
try:
(riff,
total_size,
wave) = self.stream.parse("4b 32u 4b")
except struct.error:
from audiotools.text import ERR_WAV_INVALID_WAVE
self.stream.close()
raise ValueError(ERR_WAV_INVALID_WAVE)
if riff != b'RIFF':
from audiotools.text import ERR_WAV_NOT_WAVE
self.stream.close()
raise ValueError(ERR_WAV_NOT_WAVE)
elif wave != b'WAVE':
from audiotools.text import ERR_WAV_INVALID_WAVE
self.stream.close()
raise ValueError(ERR_WAV_INVALID_WAVE)
else:
total_size -= 4
fmt_chunk_read = False
# walk through chunks until "data" chunk encountered
while total_size > 0:
try:
(chunk_id,
chunk_size) = self.stream.parse("4b 32u")
except struct.error:
from audiotools.text import ERR_WAV_INVALID_WAVE
self.stream.close()
raise ValueError(ERR_WAV_INVALID_WAVE)
if not frozenset(chunk_id).issubset(WaveAudio.PRINTABLE_ASCII):
from audiotools.text import ERR_WAV_INVALID_CHUNK
self.stream.close()
raise ValueError(ERR_WAV_INVALID_CHUNK)
else:
total_size -= 8
if chunk_id == b"fmt ":
# when "fmt " chunk encountered,
# use it to populate PCMReader attributes
(self.channels,
self.sample_rate,
self.bits_per_sample,
channel_mask) = parse_fmt(self.stream)
self.channel_mask = int(channel_mask)
self.bytes_per_pcm_frame = ((self.bits_per_sample // 8) *
self.channels)
fmt_chunk_read = True
elif chunk_id == b"data":
# when "data" chunk encountered,
# use its size to determine total PCM frames
# and ready PCMReader for reading
if not fmt_chunk_read:
from audiotools.text import ERR_WAV_PREMATURE_DATA
self.stream.close()
raise ValueError(ERR_WAV_PREMATURE_DATA)
else:
self.total_pcm_frames = (chunk_size //
self.bytes_per_pcm_frame)
self.remaining_pcm_frames = self.total_pcm_frames
self.data_start = self.stream.getpos()
return
else:
# all other chunks are ignored
self.stream.skip_bytes(chunk_size)
if chunk_size % 2:
if len(self.stream.read_bytes(1)) < 1:
from audiotools.text import ERR_WAV_INVALID_CHUNK
self.stream.close()
raise ValueError(ERR_WAV_INVALID_CHUNK)
total_size -= (chunk_size + 1)
else:
total_size -= chunk_size
else:
# raise an error if no "data" chunk is encountered
from audiotools.text import ERR_WAV_NO_DATA_CHUNK
self.stream.close()
raise ValueError(ERR_WAV_NO_DATA_CHUNK)
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
def read(self, pcm_frames):
"""try to read a pcm.FrameList with the given number of PCM frames"""
# try to read requested PCM frames or remaining frames
requested_pcm_frames = min(max(pcm_frames, 1),
self.remaining_pcm_frames)
requested_bytes = (self.bytes_per_pcm_frame *
requested_pcm_frames)
pcm_data = self.stream.read_bytes(requested_bytes)
# raise exception if "data" chunk exhausted early
if len(pcm_data) < requested_bytes:
from audiotools.text import ERR_WAV_TRUNCATED_DATA_CHUNK
raise IOError(ERR_WAV_TRUNCATED_DATA_CHUNK)
else:
self.remaining_pcm_frames -= requested_pcm_frames
# return parsed chunk
return FrameList(pcm_data,
self.channels,
self.bits_per_sample,
False,
self.bits_per_sample != 8)
def read_closed(self, pcm_frames):
raise ValueError("cannot read closed stream")
def seek(self, pcm_frame_offset):
"""tries to seek to the given PCM frame offset
returns the total amount of frames actually seeked over"""
if pcm_frame_offset < 0:
from audiotools.text import ERR_NEGATIVE_SEEK
raise ValueError(ERR_NEGATIVE_SEEK)
# ensure one doesn't walk off the end of the file
pcm_frame_offset = min(pcm_frame_offset, self.total_pcm_frames)
# position file in "data" chunk
self.stream.setpos(self.data_start)
self.stream.seek(pcm_frame_offset * self.bytes_per_pcm_frame, 1)
self.remaining_pcm_frames = (self.total_pcm_frames -
pcm_frame_offset)
return pcm_frame_offset
def seek_closed(self, pcm_frame_offset):
raise ValueError("cannot seek closed stream")
def close(self):
"""closes the stream for reading"""
self.stream.close()
self.read = self.read_closed
self.seek = self.seek_closed
class SHNDecoder(object):
def __init__(self, filename):
self.reader = BitstreamReader(open(filename, "rb"), False)
(self.file_type, self.channels, self.block_length, self.max_LPC,
self.number_of_means) = self.read_header()
if ((1 <= self.file_type) and (self.file_type <= 2)):
self.bits_per_sample = 8
self.signed_samples = (self.file_type == 1)
elif ((3 <= self.file_type) and (self.file_type <= 6)):
self.bits_per_sample = 16
self.signed_samples = (self.file_type in (3, 5))
else:
raise ValueError("unsupported Shorten file type")
self.wrapped_samples = [[0] * 3 for c in range(self.channels)]
self.means = [[0] * self.number_of_means for c in range(self.channels)]
self.left_shift = 0
self.stream_finished = False
# try to read the first command for a wave/aiff header
self.reader.mark()
self.read_metadata()
self.reader.rewind()
self.reader.unmark()
def read_metadata(self):
from io import BytesIO
command = self.unsigned(2)
if (command == 9):
# got verbatim, so read data
verbatim_bytes = ints_to_bytes(
[self.unsigned(8) & 0xFF for i in range(self.unsigned(5))])
try:
wave = BitstreamReader(BytesIO(verbatim_bytes), True)
header = wave.read_bytes(12)
if (header.startswith(b"RIFF") and header.endswith(b"WAVE")):
# got RIFF/WAVE header, so parse wave blocks as needed
total_size = len(verbatim_bytes) - 12
while (total_size > 0):
(chunk_id, chunk_size) = wave.parse("4b 32u")
total_size -= 8
if (chunk_id == b'fmt '):
(channels, self.sample_rate, bits_per_sample,
channel_mask) = parse_fmt(
wave.substream(chunk_size))
self.channel_mask = int(channel_mask)
return
else:
if (chunk_size % 2):
wave.read_bytes(chunk_size + 1)
total_size -= (chunk_size + 1)
else:
wave.read_bytes(chunk_size)
total_size -= chunk_size
else:
# no fmt chunk, so use default metadata
pass
except (IOError, ValueError):
pass
try:
aiff = BitstreamReader(BytesIO(verbatim_bytes), False)
header = aiff.read_bytes(12)
if (header.startswith(b"FORM") and header.endswith(b"AIFF")):
# got FORM/AIFF header, so parse aiff blocks as needed
total_size = len(verbatim_bytes) - 12
while (total_size > 0):
(chunk_id, chunk_size) = aiff.parse("4b 32u")
total_size -= 8
if (chunk_id == b'COMM'):
(channels, total_sample_frames, bits_per_sample,
self.sample_rate, channel_mask) = parse_comm(
aiff.substream(chunk_size))
self.channel_mask = int(channel_mask)
return
else:
if (chunk_size % 2):
aiff.read_bytes(chunk_size + 1)
total_size -= (chunk_size + 1)
else:
aiff.read_bytes(chunk_size)
total_size -= chunk_size
else:
# no COMM chunk, so use default metadata
pass
except IOError:
pass
# got something else, so invent some PCM parameters
self.sample_rate = 44100
if (self.channels == 1):
self.channel_mask = 0x4
elif (self.channels == 2):
self.channel_mask = 0x3
else:
self.channel_mask = 0
def unsigned(self, c):
MSB = self.reader.unary(1)
LSB = self.reader.read(c)
return MSB * 2**c + LSB
def signed(self, c):
u = self.unsigned(c + 1)
if ((u % 2) == 0):
return u // 2
else:
return -(u // 2) - 1
def long(self):
return self.unsigned(self.unsigned(2))
def skip_unsigned(self, c):
self.reader.skip_unary(1)
self.reader.skip(c)
def read_header(self):
magic = self.reader.read_bytes(4)
if (magic != b"ajkg"):
raise ValueError("invalid magic number")
version = self.reader.read(8)
if (version != 2):
raise ValueError("unsupported version")
file_type = self.long()
channels = self.long()
block_length = self.long()
max_LPC = self.long()
number_of_means = self.long()
bytes_to_skip = self.long()
self.reader.read_bytes(bytes_to_skip)
return (file_type, channels, block_length, max_LPC, number_of_means)
def read(self, pcm_frames):
if (self.stream_finished):
return from_channels([
empty_framelist(1, self.bits_per_sample)
for channel in range(self.channels)
])
c = 0
samples = []
unshifted = []
while (True):
command = self.unsigned(2)
if (((0 <= command) and (command <= 3)
or (7 <= command) and (command <= 8))):
# audio data commands
if (command == 0): # DIFF0
samples.append(
self.read_diff0(self.block_length, self.means[c]))
elif (command == 1): # DIFF1
samples.append(
self.read_diff1(self.block_length,
self.wrapped_samples[c]))
elif (command == 2): # DIFF2
samples.append(
self.read_diff2(self.block_length,
self.wrapped_samples[c]))
elif (command == 3): # DIFF3
samples.append(
self.read_diff3(self.block_length,
self.wrapped_samples[c]))
elif (command == 7): # QLPC
samples.append(
self.read_qlpc(self.block_length, self.means[c],
self.wrapped_samples[c]))
elif (command == 8): # ZERO
samples.append([0] * self.block_length)
# update means for channel
self.means[c].append(shnmean(samples[c]))
self.means[c] = self.means[c][1:]
# wrap samples for next command in channel
self.wrapped_samples[c] = samples[c][-(max(3, self.max_LPC)):]
# apply left shift to samples
if (self.left_shift > 0):
unshifted.append(
[s << self.left_shift for s in samples[c]])
else:
unshifted.append(samples[c])
c += 1
if (c == self.channels):
# return a FrameList from shifted data
return from_channels([
from_list(channel, 1, self.bits_per_sample,
self.signed_samples) for channel in unshifted
])
else:
# non audio commands
if (command == 4): # QUIT
self.stream_finished = True
return from_channels([
empty_framelist(1, self.bits_per_sample)
for channel in range(self.channels)
])
elif (command == 5): # BLOCKSIZE
self.block_length = self.long()
elif (command == 6): # BITSHIFT
self.left_shift = self.unsigned(2)
elif (command == 9): # VERBATIM
# skip this command during reading
size = self.unsigned(5)
for i in range(size):
self.skip_unsigned(8)
else:
raise ValueError("unsupported Shorten command")
def read_diff0(self, block_length, means):
offset = shnmean(means)
energy = self.unsigned(3)
samples = []
for i in range(block_length):
residual = self.signed(energy)
samples.append(residual + offset)
return samples
def read_diff1(self, block_length, previous_samples):
samples = previous_samples[-1:]
energy = self.unsigned(3)
for i in range(1, block_length + 1):
residual = self.signed(energy)
samples.append(samples[i - 1] + residual)
return samples[1:]
def read_diff2(self, block_length, previous_samples):
samples = previous_samples[-2:]
energy = self.unsigned(3)
for i in range(2, block_length + 2):
residual = self.signed(energy)
samples.append((2 * samples[i - 1]) - samples[i - 2] + residual)
return samples[2:]
def read_diff3(self, block_length, previous_samples):
samples = previous_samples[-3:]
energy = self.unsigned(3)
for i in range(3, block_length + 3):
residual = self.signed(energy)
samples.append((3 * (samples[i - 1] - samples[i - 2])) +
samples[i - 3] + residual)
return samples[3:]
def read_qlpc(self, block_length, means, previous_samples):
offset = shnmean(means)
energy = self.unsigned(3)
LPC_count = self.unsigned(2)
LPC_coeff = [self.signed(5) for i in range(LPC_count)]
unoffset = []
samples = previous_samples[-LPC_count:]
for i in range(block_length):
residual = self.signed(energy)
LPC_sum = 2**5
for j in range(LPC_count):
if ((i - j - 1) < 0):
# apply offset to warm-up samples
LPC_sum += (LPC_coeff[j] * (samples[LPC_count +
(i - j - 1)] - offset))
else:
LPC_sum += LPC_coeff[j] * unoffset[i - j - 1]
unoffset.append(LPC_sum // 2**5 + residual)
return [u + offset for u in unoffset]
def close(self):
self.reader.close()
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
class TTADecoder(object):
def __init__(self, filename):
self.reader = BitstreamReader(open(filename, "rb"), True)
crc = CRC32()
self.reader.add_callback(crc.update)
# read the header
(signature,
format_,
self.channels,
self.bits_per_sample,
self.sample_rate,
self.total_pcm_frames) = self.reader.parse(
"4b 16u 16u 16u 32u 32u")
self.reader.pop_callback()
header_crc = self.reader.read(32)
if int(crc) != header_crc:
raise ValueError(
"CRC32 mismatch in header (0x%8.8X != 0x%8.8X)" %
(header_crc, int(crc)))
self.channel_mask = {1: 0x4, 2: 0x3}.get(self.channels, 0)
total_tta_frames = div_ceil(self.total_pcm_frames * 245,
self.sample_rate * 256)
self.pcm_frames_per_tta_frame = (self.sample_rate * 256) // 245
# read the seektable
crc = CRC32()
self.reader.add_callback(crc.update)
self.frame_sizes = [self.reader.read(32) for i in
range(total_tta_frames)]
self.reader.pop_callback()
seektable_crc = self.reader.read(32)
if int(crc) != seektable_crc:
raise ValueError(
"CRC32 mismatch in seektable (0x%8.8X != 0x%8.8X)" %
(header_crc, int(crc)))
self.current_tta_frame = 0
def read(self, pcm_frames):
if self.total_pcm_frames == 0:
return empty_framelist(self.channels, self.bits_per_sample)
pcm_frames = min(self.pcm_frames_per_tta_frame, self.total_pcm_frames)
frame_reader = self.reader.substream(
self.frame_sizes[self.current_tta_frame])
crc = CRC32()
frame_reader.add_callback(crc.update)
self.total_pcm_frames -= pcm_frames
self.current_tta_frame += 1
# setup Rice parameters for each channel
k0 = [10] * self.channels
k1 = [10] * self.channels
sum0 = [2 ** 14] * self.channels
sum1 = [2 ** 14] * self.channels
# list of unfiltered output for each channel
unfiltered = [[] for i in range(self.channels)]
for f in range(pcm_frames):
correlated = []
for (c, ch_output) in enumerate(unfiltered):
# read most-significant bits
MSB = frame_reader.unary(0)
if MSB == 0:
# read least-significant bits
unsigned = frame_reader.read(k0[c])
else:
# read least-significant bits
LSB = frame_reader.read(k1[c])
unshifted = ((MSB - 1) << k1[c]) + LSB
unsigned = unshifted + (1 << k0[c])
# adjust sum1 and k1
sum1[c] += (unshifted - (sum1[c] >> 4))
if sum1[c] < (2 ** (k1[c] + 4)):
k1[c] = max(k1[c] - 1, 0)
elif sum1[c] > (2 ** (k1[c] + 5)):
k1[c] += 1
# adjust sum0 and k0
sum0[c] += (unsigned - (sum0[c] >> 4))
if sum0[c] < (2 ** (k0[c] + 4)):
k0[c] = max(k0[c] - 1, 0)
elif sum0[c] > (2 ** (k0[c] + 5)):
k0[c] += 1
# apply sign bit
if (unsigned % 2) == 1:
# positive
ch_output.append((unsigned + 1) // 2)
else:
# negative
ch_output.append(-(unsigned // 2))
# check frame's trailing CRC32 now that reading is finished
frame_reader.byte_align()
frame_reader.pop_callback()
frame_crc = frame_reader.read(32)
if int(crc) != frame_crc:
raise ValueError("CRC32 mismatch in frame (0x%8.8X != 0x%8.8X)" %
(frame_crc, int(crc)))
# run hybrid filter on each channel
filtered = []
for unfiltered_ch in unfiltered:
filtered.append(
tta_filter(self.bits_per_sample, unfiltered_ch))
# run fixed order prediction on each channel
predicted = []
for filtered_ch in filtered:
predicted.append(
fixed_predictor(self.bits_per_sample, filtered_ch))
if self.channels == 1:
# send channel as-is
return from_list(predicted[0],
1,
self.bits_per_sample,
True)
else:
# decorrelate channels
decorrelated = decorrelate(predicted)
# return all channels as single FrameList
return from_channels([from_list(decorrelated_ch,
1,
self.bits_per_sample,
True)
for decorrelated_ch in decorrelated])
def close(self):
self.reader.close()
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
class ALACDecoder(object):
def __init__(self, filename):
self.reader = BitstreamReader(open(filename, "rb"), False)
stream_start = self.reader.getpos()
# locate the "alac" atom
# which is full of required decoding parameters
try:
stsd = self.find_sub_atom(b"moov", b"trak", b"mdia",
b"minf", b"stbl", b"stsd")
except KeyError:
raise ValueError("required stsd atom not found")
(stsd_version, descriptions) = stsd.parse("8u 24p 32u")
(alac1,
alac2,
self.samples_per_frame,
self.bits_per_sample,
self.history_multiplier,
self.initial_history,
self.maximum_k,
self.channels,
self.sample_rate) = stsd.parse(
# ignore much of the stuff in the "high" ALAC atom
"32p 4b 6P 16p 16p 16p 4P 16p 16p 16p 16p 4P" +
# and use the attributes in the "low" ALAC atom instead
"32p 4b 4P 32u 8p 8u 8u 8u 8u 8u 16p 32p 32p 32u")
self.channel_mask = {1: 0x0004,
2: 0x0003,
3: 0x0007,
4: 0x0107,
5: 0x0037,
6: 0x003F,
7: 0x013F,
8: 0x00FF}.get(self.channels, 0)
if (alac1 != b'alac') or (alac2 != b'alac'):
raise ValueError("Invalid alac atom")
# also locate the "mdhd" atom
# which contains the stream's length in PCM frames
self.reader.setpos(stream_start)
mdhd = self.find_sub_atom(b"moov", b"trak", b"mdia", b"mdhd")
(version, ) = mdhd.parse("8u 24p")
if version == 0:
(self.total_pcm_frames,) = mdhd.parse(
"32p 32p 32p 32u 2P 16p")
elif version == 1:
(self.total_pcm_frames,) = mdhd.parse(
"64p 64p 32p 64U 2P 16p")
else:
raise ValueError("invalid mdhd version")
# finally, set our stream to the "mdat" atom
self.reader.setpos(stream_start)
(atom_size, atom_name) = self.reader.parse("32u 4b")
while atom_name != b"mdat":
self.reader.skip_bytes(atom_size - 8)
(atom_size, atom_name) = self.reader.parse("32u 4b")
def find_sub_atom(self, *atom_names):
reader = self.reader
for (last, next_atom) in iter_last(iter(atom_names)):
try:
(length, stream_atom) = reader.parse("32u 4b")
while stream_atom != next_atom:
reader.skip_bytes(length - 8)
(length, stream_atom) = reader.parse("32u 4b")
if last:
return reader.substream(length - 8)
else:
reader = reader.substream(length - 8)
except IOError:
raise KeyError(next_atom)
def read(self, pcm_frames):
# if the stream is exhausted, return an empty pcm.FrameList object
if self.total_pcm_frames == 0:
return empty_framelist(self.channels, self.bits_per_sample)
# otherwise, read one ALAC frameset's worth of frame data
frameset_data = []
frame_channels = self.reader.read(3) + 1
while frame_channels != 0x8:
frameset_data.extend(self.read_frame(frame_channels))
frame_channels = self.reader.read(3) + 1
self.reader.byte_align()
# reorder the frameset to Wave order, depending on channel count
if (self.channels == 1) or (self.channels == 2):
pass
elif self.channels == 3:
frameset_data = [frameset_data[1],
frameset_data[2],
frameset_data[0]]
elif self.channels == 4:
frameset_data = [frameset_data[1],
frameset_data[2],
frameset_data[0],
frameset_data[3]]
elif self.channels == 5:
frameset_data = [frameset_data[1],
frameset_data[2],
frameset_data[0],
frameset_data[3],
frameset_data[4]]
elif self.channels == 6:
frameset_data = [frameset_data[1],
frameset_data[2],
frameset_data[0],
frameset_data[5],
frameset_data[3],
frameset_data[4]]
elif self.channels == 7:
frameset_data = [frameset_data[1],
frameset_data[2],
frameset_data[0],
frameset_data[6],
frameset_data[3],
frameset_data[4],
frameset_data[5]]
elif self.channels == 8:
frameset_data = [frameset_data[3],
frameset_data[4],
frameset_data[0],
frameset_data[7],
frameset_data[5],
frameset_data[6],
frameset_data[1],
frameset_data[2]]
else:
raise ValueError("unsupported channel count")
framelist = from_channels([from_list(channel,
1,
self.bits_per_sample,
True)
for channel in frameset_data])
# deduct PCM frames from remainder
self.total_pcm_frames -= framelist.frames
# return samples as a pcm.FrameList object
return framelist
def read_frame(self, channel_count):
"""returns a list of PCM sample lists, one per channel"""
# read the ALAC frame header
self.reader.skip(16)
has_sample_count = self.reader.read(1)
uncompressed_lsb_size = self.reader.read(2)
uncompressed = self.reader.read(1)
if has_sample_count:
sample_count = self.reader.read(32)
else:
sample_count = self.samples_per_frame
if uncompressed == 1:
# if the frame is uncompressed,
# read the raw, interlaced samples
samples = [self.reader.read_signed(self.bits_per_sample)
for i in range(sample_count * channel_count)]
return [samples[i::channel_count] for i in range(channel_count)]
else:
# if the frame is compressed,
# read the interlacing parameters
interlacing_shift = self.reader.read(8)
interlacing_leftweight = self.reader.read(8)
# subframe headers
subframe_headers = [self.read_subframe_header()
for i in range(channel_count)]
# optional uncompressed LSB values
if uncompressed_lsb_size > 0:
uncompressed_lsbs = [
self.reader.read(uncompressed_lsb_size * 8)
for i in range(sample_count * channel_count)]
else:
uncompressed_lsbs = []
sample_size = (self.bits_per_sample -
(uncompressed_lsb_size * 8) +
channel_count - 1)
# and residual blocks
residual_blocks = [self.read_residuals(sample_size,
sample_count)
for i in range(channel_count)]
# calculate subframe samples based on
# subframe header's QLP coefficients and QLP shift-needed
decoded_subframes = [self.decode_subframe(header[0],
header[1],
sample_size,
residuals)
for (header, residuals) in
zip(subframe_headers,
residual_blocks)]
# decorrelate channels according interlacing shift and leftweight
decorrelated_channels = self.decorrelate_channels(
decoded_subframes,
interlacing_shift,
interlacing_leftweight)
# if uncompressed LSB values are present,
# prepend them to each sample of each channel
if uncompressed_lsb_size > 0:
channels = []
for (i, channel) in enumerate(decorrelated_channels):
assert(len(channel) ==
len(uncompressed_lsbs[i::channel_count]))
channels.append([s << (uncompressed_lsb_size * 8) | l
for (s, l) in
zip(channel,
uncompressed_lsbs[i::channel_count])])
return channels
else:
return decorrelated_channels
def read_subframe_header(self):
prediction_type = self.reader.read(4)
qlp_shift_needed = self.reader.read(4)
rice_modifier = self.reader.read(3)
qlp_coefficients = [self.reader.read_signed(16)
for i in range(self.reader.read(5))]
return (qlp_shift_needed, qlp_coefficients)
def read_residuals(self, sample_size, sample_count):
residuals = []
history = self.initial_history
sign_modifier = 0
i = 0
while i < sample_count:
# get an unsigned residual based on "history"
# and on "sample_size" as a lst resort
k = min(log2(history // (2 ** 9) + 3), self.maximum_k)
unsigned = self.read_residual(k, sample_size) + sign_modifier
# clear out old sign modifier, if any
sign_modifier = 0
# change unsigned residual to signed residual
if unsigned & 1:
residuals.append(-((unsigned + 1) // 2))
else:
residuals.append(unsigned // 2)
# update history based on unsigned residual
if unsigned <= 0xFFFF:
history += ((unsigned * self.history_multiplier) -
((history * self.history_multiplier) >> 9))
else:
history = 0xFFFF
# if history gets too small, we may have a block of 0 samples
# which can be compressed more efficiently
if (history < 128) and ((i + 1) < sample_count):
zeroes_k = min(7 -
log2(history) +
((history + 16) // 64),
self.maximum_k)
zero_residuals = self.read_residual(zeroes_k, 16)
if zero_residuals > 0:
residuals.extend([0] * zero_residuals)
i += zero_residuals
history = 0
if zero_residuals <= 0xFFFF:
sign_modifier = 1
i += 1
return residuals
def read_residual(self, k, sample_size):
msb = self.reader.read_huffman_code(RESIDUAL)
if msb == -1:
return self.reader.read(sample_size)
elif k == 0:
return msb
else:
lsb = self.reader.read(k)
if lsb > 1:
return msb * ((1 << k) - 1) + (lsb - 1)
elif lsb == 1:
self.reader.unread(1)
return msb * ((1 << k) - 1)
else:
self.reader.unread(0)
return msb * ((1 << k) - 1)
def decode_subframe(self, qlp_shift_needed, qlp_coefficients,
sample_size, residuals):
# first sample is always copied verbatim
samples = [residuals.pop(0)]
if len(qlp_coefficients) < 31:
# the next "coefficient count" samples
# are applied as differences to the previous
for i in range(len(qlp_coefficients)):
samples.append(truncate_bits(samples[-1] + residuals.pop(0),
sample_size))
# remaining samples are processed much like LPC
for residual in residuals:
base_sample = samples[-len(qlp_coefficients) - 1]
lpc_sum = sum([(s - base_sample) * c for (s, c) in
zip(samples[-len(qlp_coefficients):],
reversed(qlp_coefficients))])
outval = (1 << (qlp_shift_needed - 1)) + lpc_sum
outval >>= qlp_shift_needed
samples.append(truncate_bits(outval + residual + base_sample,
sample_size))
buf = samples[-len(qlp_coefficients) - 2:-1]
# error value then adjusts the coefficients table
if residual > 0:
predictor_num = len(qlp_coefficients) - 1
while (predictor_num >= 0) and residual > 0:
val = (buf[0] -
buf[len(qlp_coefficients) - predictor_num])
sign = sign_only(val)
qlp_coefficients[predictor_num] -= sign
val *= sign
residual -= ((val >> qlp_shift_needed) *
(len(qlp_coefficients) - predictor_num))
predictor_num -= 1
elif residual < 0:
# the same as above, but we break if residual goes positive
predictor_num = len(qlp_coefficients) - 1
while (predictor_num >= 0) and (residual < 0):
val = (buf[0] -
buf[len(qlp_coefficients) - predictor_num])
sign = -sign_only(val)
qlp_coefficients[predictor_num] -= sign
val *= sign
residual -= ((val >> qlp_shift_needed) *
(len(qlp_coefficients) - predictor_num))
predictor_num -= 1
else:
# residuals are encoded as simple difference values
for residual in residuals:
samples.append(truncate_bits(samples[-1] + residual,
sample_size))
return samples
def decorrelate_channels(self, channel_data,
interlacing_shift, interlacing_leftweight):
if len(channel_data) != 2:
return channel_data
elif interlacing_leftweight == 0:
return channel_data
else:
left = []
right = []
for (ch1, ch2) in zip(*channel_data):
right.append(ch1 - ((ch2 * interlacing_leftweight) //
(2 ** interlacing_shift)))
left.append(ch2 + right[-1])
return [left, right]
def close(self):
self.reader.close()
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
class WavPackDecoder(object):
def __init__(self, filename):
self.reader = BitstreamReader(open(filename, "rb"), 1)
# read initial block to populate
# sample_rate, bits_per_sample, channels, and channel_mask
self.reader.mark()
block_header = Block_Header.read(self.reader)
sub_blocks_size = block_header.block_size - 24
sub_blocks_data = self.reader.substream(sub_blocks_size)
if (block_header.sample_rate != 15):
self.sample_rate = [
6000, 8000, 9600, 11025, 12000, 16000, 22050, 24000, 32000,
44100, 48000, 64000, 88200, 96000, 192000
][block_header.sample_rate]
else:
sub_blocks_data.mark()
try:
for sub_block in sub_blocks(sub_blocks_data, sub_blocks_size):
if (((sub_block.metadata_function == 7)
and (sub_block.nondecoder_data == 1))):
self.sample_rate = sub_block.data.read(
sub_block.data_size() * 8)
break
else:
raise ValueError("invalid sample rate")
finally:
sub_blocks_data.rewind()
sub_blocks_data.unmark()
self.bits_per_sample = [8, 16, 24, 32][block_header.bits_per_sample]
if (block_header.initial_block and block_header.final_block):
if (((block_header.mono_output == 0)
or (block_header.false_stereo == 1))):
self.channels = 2
self.channel_mask = 0x3
else:
self.channels = 1
self.channel_mask = 0x4
else:
# look for channel mask sub block
sub_blocks_data.mark()
for sub_block in sub_blocks(sub_blocks_data, sub_blocks_size):
if (((sub_block.metadata_function == 13)
and (sub_block.nondecoder_data == 0))):
self.channels = sub_block.data.read(8)
self.channel_mask = sub_block.data.read(
(sub_block.data_size() - 1) * 8)
break
else:
# FIXME - handle case of no channel mask sub block
raise NotImplementedError()
sub_blocks_data.rewind()
sub_blocks_data.unmark()
self.reader.rewind()
self.reader.unmark()
self.pcm_finished = False
self.md5_checked = False
self.md5sum = md5()
def read(self, pcm_frames):
if (self.pcm_finished):
if (not self.md5_checked):
self.reader.mark()
try:
try:
header = Block_Header.read(self.reader)
sub_blocks_size = header.block_size - 24
sub_blocks_data = \
self.reader.substream(sub_blocks_size)
for sub_block in sub_blocks(sub_blocks_data,
sub_blocks_size):
if (((sub_block.metadata_function == 6)
and (sub_block.nondecoder_data == 1))):
if ((sub_block.data.read_bytes(16) !=
self.md5sum.digest())):
raise ValueError("invalid stream MD5 sum")
except (IOError, ValueError):
# no error if a block isn't found
pass
finally:
self.reader.rewind()
self.reader.unmark()
return from_list([], self.channels, self.bits_per_sample, True)
channels = []
while (True): # in place of a do-while loop
try:
block_header = Block_Header.read(self.reader)
except (ValueError, IOError):
self.pcm_finished = True
return from_list([], self.channels, self.bits_per_sample, True)
sub_blocks_size = block_header.block_size - 24
sub_blocks_data = self.reader.substream(sub_blocks_size)
channels.extend(
read_block(block_header, sub_blocks_size, sub_blocks_data))
if (block_header.final_block == 1):
break
if ((block_header.block_index + block_header.block_samples) >=
block_header.total_samples):
self.pcm_finished = True
# combine channels of audio data into single block
block = from_channels(
[from_list(ch, 1, self.bits_per_sample, True) for ch in channels])
# update MD5 sum
self.md5sum.update(block.to_bytes(False, self.bits_per_sample > 8))
# return single block of audio data
return block
def close(self):
self.reader.close()
def __init__(self, filename):
"""filename is a plain string"""
from audiotools.bitstream import BitstreamReader
from audiotools import ChannelMask
from io import BytesIO
def read_unsigned(r, c):
MSB = r.unary(1)
LSB = r.read(c)
return MSB * 2 ** c + LSB
def read_long(r):
return read_unsigned(r, read_unsigned(r, 2))
WaveContainer.__init__(self, filename)
try:
reader = BitstreamReader(open(filename, "rb"), False)
except IOError as msg:
raise InvalidShorten(str(msg))
try:
if (reader.parse("4b 8u") != [b"ajkg", 2]):
raise InvalidShorten("invalid Shorten header")
# populate channels and bits_per_sample from Shorten header
(file_type,
self.__channels__,
block_length,
max_LPC,
number_of_means,
bytes_to_skip) = [read_long(reader) for i in range(6)]
if ((1 <= file_type) and (file_type <= 2)):
self.__bits_per_sample__ = 8
elif ((3 <= file_type) and (file_type <= 6)):
self.__bits_per_sample__ = 16
else:
# FIXME
raise InvalidShorten("unsupported Shorten file type")
# setup some default dummy metadata
self.__sample_rate__ = 44100
if (self.__channels__ == 1):
self.__channel_mask__ = ChannelMask(0x4)
elif (self.__channels__ == 2):
self.__channel_mask__ = ChannelMask(0x3)
else:
self.__channel_mask__ = ChannelMask(0)
self.__total_frames__ = 0
# populate sample_rate and total_frames
# from first VERBATIM command
command = read_unsigned(reader, 2)
if (command == 9):
if (sys.version_info[0] >= 3):
verbatim_bytes = \
bytes([read_unsigned(reader, 8) & 0xFF
for i in range(read_unsigned(reader, 5))])
else:
verbatim_bytes = \
b"".join([chr(read_unsigned(reader, 8) & 0xFF)
for i in range(read_unsigned(reader, 5))])
try:
wave = BitstreamReader(BytesIO(verbatim_bytes), True)
header = wave.read_bytes(12)
if (header.startswith(b"RIFF") and
header.endswith(b"WAVE")):
# got RIFF/WAVE header,
# so parse wave blocks as needed
total_size = len(verbatim_bytes) - 12
while (total_size >= 8):
(chunk_id, chunk_size) = wave.parse("4b 32u")
total_size -= 8
if (chunk_id == b'fmt '):
from audiotools.wav import parse_fmt
(channels,
self.__sample_rate__,
bits_per_sample,
self.__channel_mask__) = parse_fmt(
wave.substream(chunk_size))
elif (chunk_id == b'data'):
self.__total_frames__ = \
(chunk_size //
(self.__channels__ *
(self.__bits_per_sample__ // 8)))
else:
if (chunk_size % 2):
wave.read_bytes(chunk_size + 1)
total_size -= (chunk_size + 1)
else:
wave.read_bytes(chunk_size)
total_size -= chunk_size
except (IOError, ValueError):
pass
try:
aiff = BitstreamReader(BytesIO(verbatim_bytes), False)
header = aiff.read_bytes(12)
if (header.startswith(b"FORM") and
header.endswith(b"AIFF")):
# got FORM/AIFF header
# so parse aiff blocks as needed
total_size = len(verbatim_bytes) - 12
while (total_size >= 8):
(chunk_id, chunk_size) = aiff.parse("4b 32u")
total_size -= 8
if (chunk_id == b'COMM'):
from audiotools.aiff import parse_comm
(channels,
total_sample_frames,
bits_per_sample,
self.__sample_rate__,
self.__channel_mask__) = parse_comm(
aiff.substream(chunk_size))
elif (chunk_id == b'SSND'):
# subtract 8 bytes for
# "offset" and "block size"
self.__total_frames__ = \
((chunk_size - 8) //
(self.__channels__ *
(self.__bits_per_sample__ // 8)))
else:
if (chunk_size % 2):
aiff.read_bytes(chunk_size + 1)
total_size -= (chunk_size + 1)
else:
aiff.read_bytes(chunk_size)
total_size -= chunk_size
except IOError:
pass
except IOError as msg:
raise InvalidShorten(str(msg))
finally:
reader.close()
class ALACDecoder(object):
def __init__(self, filename):
self.reader = BitstreamReader(open(filename, "rb"), False)
self.reader.mark()
try:
# locate the "alac" atom
# which is full of required decoding parameters
try:
stsd = self.find_sub_atom(b"moov", b"trak", b"mdia", b"minf",
b"stbl", b"stsd")
except KeyError:
raise ValueError("required stsd atom not found")
(stsd_version, descriptions) = stsd.parse("8u 24p 32u")
(alac1, alac2, self.samples_per_frame, self.bits_per_sample,
self.history_multiplier, self.initial_history, self.maximum_k,
self.channels, self.sample_rate) = stsd.parse(
# ignore much of the stuff in the "high" ALAC atom
"32p 4b 6P 16p 16p 16p 4P 16p 16p 16p 16p 4P" +
# and use the attributes in the "low" ALAC atom instead
"32p 4b 4P 32u 8p 8u 8u 8u 8u 8u 16p 32p 32p 32u")
self.channel_mask = {
1: 0x0004,
2: 0x0003,
3: 0x0007,
4: 0x0107,
5: 0x0037,
6: 0x003F,
7: 0x013F,
8: 0x00FF
}.get(self.channels, 0)
if ((alac1 != b'alac') or (alac2 != b'alac')):
raise ValueError("Invalid alac atom")
# also locate the "mdhd" atom
# which contains the stream's length in PCM frames
self.reader.rewind()
mdhd = self.find_sub_atom(b"moov", b"trak", b"mdia", b"mdhd")
(version, ) = mdhd.parse("8u 24p")
if (version == 0):
(self.total_pcm_frames,
) = mdhd.parse("32p 32p 32p 32u 2P 16p")
elif (version == 1):
(self.total_pcm_frames,
) = mdhd.parse("64p 64p 32p 64U 2P 16p")
else:
raise ValueError("invalid mdhd version")
# finally, set our stream to the "mdat" atom
self.reader.rewind()
(atom_size, atom_name) = self.reader.parse("32u 4b")
while (atom_name != b"mdat"):
self.reader.skip_bytes(atom_size - 8)
(atom_size, atom_name) = self.reader.parse("32u 4b")
finally:
self.reader.unmark()
def find_sub_atom(self, *atom_names):
reader = self.reader
for (last, next_atom) in iter_last(iter(atom_names)):
try:
(length, stream_atom) = reader.parse("32u 4b")
while (stream_atom != next_atom):
reader.skip_bytes(length - 8)
(length, stream_atom) = reader.parse("32u 4b")
if (last):
return reader.substream(length - 8)
else:
reader = reader.substream(length - 8)
except IOError:
raise KeyError(next_atom)
def read(self, pcm_frames):
# if the stream is exhausted, return an empty pcm.FrameList object
if (self.total_pcm_frames == 0):
return empty_framelist(self.channels, self.bits_per_sample)
# otherwise, read one ALAC frameset's worth of frame data
frameset_data = []
frame_channels = self.reader.read(3) + 1
while (frame_channels != 0x8):
frameset_data.extend(self.read_frame(frame_channels))
frame_channels = self.reader.read(3) + 1
self.reader.byte_align()
# reorder the frameset to Wave order, depending on channel count
if ((self.channels == 1) or (self.channels == 2)):
pass
elif (self.channels == 3):
frameset_data = [
frameset_data[1], frameset_data[2], frameset_data[0]
]
elif (self.channels == 4):
frameset_data = [
frameset_data[1], frameset_data[2], frameset_data[0],
frameset_data[3]
]
elif (self.channels == 5):
frameset_data = [
frameset_data[1], frameset_data[2], frameset_data[0],
frameset_data[3], frameset_data[4]
]
elif (self.channels == 6):
frameset_data = [
frameset_data[1], frameset_data[2], frameset_data[0],
frameset_data[5], frameset_data[3], frameset_data[4]
]
elif (self.channels == 7):
frameset_data = [
frameset_data[1], frameset_data[2], frameset_data[0],
frameset_data[6], frameset_data[3], frameset_data[4],
frameset_data[5]
]
elif (self.channels == 8):
frameset_data = [
frameset_data[3], frameset_data[4], frameset_data[0],
frameset_data[7], frameset_data[5], frameset_data[6],
frameset_data[1], frameset_data[2]
]
else:
raise ValueError("unsupported channel count")
framelist = from_channels([
from_list(channel, 1, self.bits_per_sample, True)
for channel in frameset_data
])
# deduct PCM frames from remainder
self.total_pcm_frames -= framelist.frames
# return samples as a pcm.FrameList object
return framelist
def read_frame(self, channel_count):
"""returns a list of PCM sample lists, one per channel"""
# read the ALAC frame header
self.reader.skip(16)
has_sample_count = self.reader.read(1)
uncompressed_lsb_size = self.reader.read(2)
uncompressed = self.reader.read(1)
if (has_sample_count):
sample_count = self.reader.read(32)
else:
sample_count = self.samples_per_frame
if (uncompressed == 1):
# if the frame is uncompressed,
# read the raw, interlaced samples
samples = [
self.reader.read_signed(self.bits_per_sample)
for i in range(sample_count * channel_count)
]
return [samples[i::channel_count] for i in range(channel_count)]
else:
# if the frame is compressed,
# read the interlacing parameters
interlacing_shift = self.reader.read(8)
interlacing_leftweight = self.reader.read(8)
# subframe headers
subframe_headers = [
self.read_subframe_header() for i in range(channel_count)
]
# optional uncompressed LSB values
if (uncompressed_lsb_size > 0):
uncompressed_lsbs = [
self.reader.read(uncompressed_lsb_size * 8)
for i in range(sample_count * channel_count)
]
else:
uncompressed_lsbs = []
sample_size = (self.bits_per_sample - (uncompressed_lsb_size * 8) +
channel_count - 1)
# and residual blocks
residual_blocks = [
self.read_residuals(sample_size, sample_count)
for i in range(channel_count)
]
# calculate subframe samples based on
# subframe header's QLP coefficients and QLP shift-needed
decoded_subframes = [
self.decode_subframe(header[0], header[1], sample_size,
residuals)
for (header,
residuals) in zip(subframe_headers, residual_blocks)
]
# decorrelate channels according interlacing shift and leftweight
decorrelated_channels = self.decorrelate_channels(
decoded_subframes, interlacing_shift, interlacing_leftweight)
# if uncompressed LSB values are present,
# prepend them to each sample of each channel
if (uncompressed_lsb_size > 0):
channels = []
for (i, channel) in enumerate(decorrelated_channels):
assert (len(channel) == len(
uncompressed_lsbs[i::channel_count]))
channels.append([
s << (uncompressed_lsb_size * 8) | l for (s, l) in zip(
channel, uncompressed_lsbs[i::channel_count])
])
return channels
else:
return decorrelated_channels
def read_subframe_header(self):
prediction_type = self.reader.read(4)
qlp_shift_needed = self.reader.read(4)
rice_modifier = self.reader.read(3)
qlp_coefficients = [
self.reader.read_signed(16) for i in range(self.reader.read(5))
]
return (qlp_shift_needed, qlp_coefficients)
def read_residuals(self, sample_size, sample_count):
residuals = []
history = self.initial_history
sign_modifier = 0
i = 0
while (i < sample_count):
# get an unsigned residual based on "history"
# and on "sample_size" as a lst resort
k = min(log2(history // (2**9) + 3), self.maximum_k)
unsigned = self.read_residual(k, sample_size) + sign_modifier
# clear out old sign modifier, if any
sign_modifier = 0
# change unsigned residual to signed residual
if (unsigned & 1):
residuals.append(-((unsigned + 1) // 2))
else:
residuals.append(unsigned // 2)
# update history based on unsigned residual
if (unsigned <= 0xFFFF):
history += ((unsigned * self.history_multiplier) -
((history * self.history_multiplier) >> 9))
else:
history = 0xFFFF
# if history gets too small, we may have a block of 0 samples
# which can be compressed more efficiently
if ((history < 128) and ((i + 1) < sample_count)):
zeroes_k = min(7 - log2(history) + ((history + 16) // 64),
self.maximum_k)
zero_residuals = self.read_residual(zeroes_k, 16)
if (zero_residuals > 0):
residuals.extend([0] * zero_residuals)
i += zero_residuals
history = 0
if (zero_residuals <= 0xFFFF):
sign_modifier = 1
i += 1
return residuals
def read_residual(self, k, sample_size):
msb = self.reader.read_huffman_code(RESIDUAL)
if (msb == -1):
return self.reader.read(sample_size)
elif (k == 0):
return msb
else:
lsb = self.reader.read(k)
if (lsb > 1):
return msb * ((1 << k) - 1) + (lsb - 1)
elif (lsb == 1):
self.reader.unread(1)
return msb * ((1 << k) - 1)
else:
self.reader.unread(0)
return msb * ((1 << k) - 1)
def decode_subframe(self, qlp_shift_needed, qlp_coefficients, sample_size,
residuals):
# first sample is always copied verbatim
samples = [residuals.pop(0)]
if (len(qlp_coefficients) < 31):
# the next "coefficient count" samples
# are applied as differences to the previous
for i in range(len(qlp_coefficients)):
samples.append(
truncate_bits(samples[-1] + residuals.pop(0), sample_size))
# remaining samples are processed much like LPC
for residual in residuals:
base_sample = samples[-len(qlp_coefficients) - 1]
lpc_sum = sum([(s - base_sample) * c
for (s,
c) in zip(samples[-len(qlp_coefficients):],
reversed(qlp_coefficients))])
outval = (1 << (qlp_shift_needed - 1)) + lpc_sum
outval >>= qlp_shift_needed
samples.append(
truncate_bits(outval + residual + base_sample,
sample_size))
buf = samples[-len(qlp_coefficients) - 2:-1]
# error value then adjusts the coefficients table
if (residual > 0):
predictor_num = len(qlp_coefficients) - 1
while ((predictor_num >= 0) and residual > 0):
val = (buf[0] -
buf[len(qlp_coefficients) - predictor_num])
sign = sign_only(val)
qlp_coefficients[predictor_num] -= sign
val *= sign
residual -= ((val >> qlp_shift_needed) *
(len(qlp_coefficients) - predictor_num))
predictor_num -= 1
elif (residual < 0):
# the same as above, but we break if residual goes positive
predictor_num = len(qlp_coefficients) - 1
while ((predictor_num >= 0) and residual < 0):
val = (buf[0] -
buf[len(qlp_coefficients) - predictor_num])
sign = -sign_only(val)
qlp_coefficients[predictor_num] -= sign
val *= sign
residual -= ((val >> qlp_shift_needed) *
(len(qlp_coefficients) - predictor_num))
predictor_num -= 1
else:
# residuals are encoded as simple difference values
for residual in residuals:
samples.append(
truncate_bits(samples[-1] + residual, sample_size))
return samples
def decorrelate_channels(self, channel_data, interlacing_shift,
interlacing_leftweight):
if (len(channel_data) != 2):
return channel_data
elif (interlacing_leftweight == 0):
return channel_data
else:
left = []
right = []
for (ch1, ch2) in zip(*channel_data):
right.append(ch1 - ((ch2 * interlacing_leftweight) //
(2**interlacing_shift)))
left.append(ch2 + right[-1])
return [left, right]
def close(self):
self.reader.close()
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
def wave_header_footer(self):
"""returns a pair of data strings before and after PCM data
the first contains all data before the PCM content of the data chunk
the second containing all data after the data chunk
for example:
>>> w = audiotools.open("input.wav")
>>> (head, tail) = w.wave_header_footer()
>>> f = open("output.wav", "wb")
>>> f.write(head)
>>> audiotools.transfer_framelist_data(w.to_pcm(), f.write)
>>> f.write(tail)
>>> f.close()
should result in "output.wav" being identical to "input.wav"
"""
from audiotools.bitstream import BitstreamReader
from audiotools.bitstream import BitstreamRecorder
head = BitstreamRecorder(1)
tail = BitstreamRecorder(1)
current_block = head
fmt_found = False
wave_file = BitstreamReader(open(self.filename, 'rb'), 1)
try:
# transfer the 12-byte "RIFFsizeWAVE" header to head
(riff, size, wave) = wave_file.parse("4b 32u 4b")
if (riff != 'RIFF'):
from audiotools.text import ERR_WAV_NOT_WAVE
raise ValueError(ERR_WAV_NOT_WAVE)
elif (wave != 'WAVE'):
from audiotools.text import ERR_WAV_INVALID_WAVE
raise ValueError(ERR_WAV_INVALID_WAVE)
else:
current_block.build("4b 32u 4b", (riff, size, wave))
total_size = size - 4
while (total_size > 0):
# transfer each chunk header
(chunk_id, chunk_size) = wave_file.parse("4b 32u")
if (not frozenset(chunk_id).issubset(self.PRINTABLE_ASCII)):
from audiotools.text import ERR_WAV_INVALID_CHUNK
raise ValueError(ERR_WAV_INVALID_CHUNK)
else:
current_block.build("4b 32u", (chunk_id, chunk_size))
total_size -= 8
# and transfer the full content of non-audio chunks
if (chunk_id != "data"):
if (chunk_id == "fmt "):
if (not fmt_found):
fmt_found = True
else:
from audiotools.text import ERR_WAV_MULTIPLE_FMT
raise ValueError(ERR_WAV_MULTIPLE_FMT)
if (chunk_size % 2):
current_block.write_bytes(
wave_file.read_bytes(chunk_size + 1))
total_size -= (chunk_size + 1)
else:
current_block.write_bytes(
wave_file.read_bytes(chunk_size))
total_size -= chunk_size
else:
wave_file.skip_bytes(chunk_size)
current_block = tail
if (chunk_size % 2):
current_block.write_bytes(wave_file.read_bytes(1))
total_size -= (chunk_size + 1)
else:
total_size -= chunk_size
if (fmt_found):
return (head.data(), tail.data())
else:
from audiotools.text import ERR_WAV_NO_FMT_CHUNK
return ValueError(ERR_WAV_NO_FMT_CHUNK)
finally:
wave_file.close()
class TTADecoder(object):
def __init__(self, filename):
self.reader = BitstreamReader(open(filename, "rb"), True)
crc = CRC32()
self.reader.add_callback(crc.update)
# read the header
(signature,
format_,
self.channels,
self.bits_per_sample,
self.sample_rate,
self.total_pcm_frames) = self.reader.parse(
"4b 16u 16u 16u 32u 32u")
self.reader.pop_callback()
header_crc = self.reader.read(32)
if (int(crc) != header_crc):
raise ValueError(
"CRC32 mismatch in header (0x%8.8X != 0x%8.8X)" %
(header_crc, int(crc)))
self.channel_mask = {1: 0x4, 2: 0x3}.get(self.channels, 0)
total_tta_frames = div_ceil(self.total_pcm_frames * 245,
self.sample_rate * 256)
self.pcm_frames_per_tta_frame = (self.sample_rate * 256) // 245
# read the seektable
crc = CRC32()
self.reader.add_callback(crc.update)
self.frame_sizes = [self.reader.read(32) for i in
range(total_tta_frames)]
self.reader.pop_callback()
seektable_crc = self.reader.read(32)
if (int(crc) != seektable_crc):
raise ValueError(
"CRC32 mismatch in seektable (0x%8.8X != 0x%8.8X)" %
(header_crc, int(crc)))
self.current_tta_frame = 0
def read(self, pcm_frames):
if (self.total_pcm_frames == 0):
return empty_framelist(self.channels, self.bits_per_sample)
pcm_frames = min(self.pcm_frames_per_tta_frame, self.total_pcm_frames)
frame_reader = self.reader.substream(
self.frame_sizes[self.current_tta_frame])
crc = CRC32()
frame_reader.add_callback(crc.update)
self.total_pcm_frames -= pcm_frames
self.current_tta_frame += 1
# setup Rice parameters for each channel
k0 = [10] * self.channels
k1 = [10] * self.channels
sum0 = [2 ** 14] * self.channels
sum1 = [2 ** 14] * self.channels
# list of unfiltered output for each channel
unfiltered = [[] for i in range(self.channels)]
for f in range(pcm_frames):
correlated = []
for (c, ch_output) in enumerate(unfiltered):
# read most-significant bits
MSB = frame_reader.unary(0)
if (MSB == 0):
# read least-significant bits
unsigned = frame_reader.read(k0[c])
else:
# read least-significant bits
LSB = frame_reader.read(k1[c])
unshifted = ((MSB - 1) << k1[c]) + LSB
unsigned = unshifted + (1 << k0[c])
# adjust sum1 and k1
sum1[c] += (unshifted - (sum1[c] >> 4))
if (sum1[c] < (2 ** (k1[c] + 4))):
k1[c] = max(k1[c] - 1, 0)
elif (sum1[c] > (2 ** (k1[c] + 5))):
k1[c] += 1
# adjust sum0 and k0
sum0[c] += (unsigned - (sum0[c] >> 4))
if (sum0[c] < (2 ** (k0[c] + 4))):
k0[c] = max(k0[c] - 1, 0)
elif (sum0[c] > (2 ** (k0[c] + 5))):
k0[c] += 1
# apply sign bit
if ((unsigned % 2) == 1):
# positive
ch_output.append((unsigned + 1) // 2)
else:
# negative
ch_output.append(-(unsigned // 2))
# check frame's trailing CRC32 now that reading is finished
frame_reader.byte_align()
frame_reader.pop_callback()
frame_crc = frame_reader.read(32)
if (int(crc) != frame_crc):
raise ValueError("CRC32 mismatch in frame (0x%8.8X != 0x%8.8X)" %
(frame_crc, int(crc)))
# run hybrid filter on each channel
filtered = []
for unfiltered_ch in unfiltered:
filtered.append(
tta_filter(self.bits_per_sample, unfiltered_ch))
# run fixed order prediction on each channel
predicted = []
for filtered_ch in filtered:
predicted.append(
fixed_predictor(self.bits_per_sample, filtered_ch))
if (self.channels == 1):
# send channel as-is
return from_list(predicted[0],
1,
self.bits_per_sample,
True)
else:
# decorrelate channels
decorrelated = decorrelate(predicted)
# return all channels as single FrameList
return from_channels([from_list(decorrelated_ch,
1,
self.bits_per_sample,
True)
for decorrelated_ch in decorrelated])
def close(self):
self.reader.close()
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
def aiff_header_footer(self):
"""returns (header, footer) tuple of strings
containing all data before and after the PCM stream
if self.has_foreign_aiff_chunks() is False,
may raise ValueError if the file has no header and footer
for any reason"""
from audiotools.bitstream import BitstreamReader
from audiotools.bitstream import BitstreamRecorder
from audiotools.text import (ERR_AIFF_NOT_AIFF,
ERR_AIFF_INVALID_AIFF,
ERR_AIFF_INVALID_CHUNK_ID)
head = BitstreamRecorder(0)
tail = BitstreamRecorder(0)
current_block = head
aiff_file = BitstreamReader(open(self.filename, 'rb'), 0)
try:
# transfer the 12-byte "RIFFsizeWAVE" header to head
(form, size, aiff) = aiff_file.parse("4b 32u 4b")
if (form != 'FORM'):
raise InvalidAIFF(ERR_AIFF_NOT_AIFF)
elif (aiff != 'AIFF'):
raise InvalidAIFF(ERR_AIFF_INVALID_AIFF)
else:
current_block.build("4b 32u 4b", (form, size, aiff))
total_size = size - 4
while (total_size > 0):
# transfer each chunk header
(chunk_id, chunk_size) = aiff_file.parse("4b 32u")
if (not frozenset(chunk_id).issubset(self.PRINTABLE_ASCII)):
raise InvalidAIFF(ERR_AIFF_INVALID_CHUNK_ID)
else:
current_block.build("4b 32u", (chunk_id, chunk_size))
total_size -= 8
# and transfer the full content of non-audio chunks
if (chunk_id != "SSND"):
if (chunk_size % 2):
current_block.write_bytes(
aiff_file.read_bytes(chunk_size + 1))
total_size -= (chunk_size + 1)
else:
current_block.write_bytes(
aiff_file.read_bytes(chunk_size))
total_size -= chunk_size
else:
# transfer alignment as part of SSND's chunk header
align = aiff_file.parse("32u 32u")
current_block.build("32u 32u", align)
aiff_file.skip_bytes(chunk_size - 8)
current_block = tail
if (chunk_size % 2):
current_block.write_bytes(aiff_file.read_bytes(1))
total_size -= (chunk_size + 1)
else:
total_size -= chunk_size
return (head.data(), tail.data())
finally:
aiff_file.close()
def __read_info__(self):
from audiotools.bitstream import BitstreamReader
from audiotools import ChannelMask
reader = BitstreamReader(open(self.filename, "rb"), 1)
reader.mark()
try:
(block_id,
total_samples,
bits_per_sample,
mono_output,
initial_block,
final_block,
sample_rate) = reader.parse(
"4b 64p 32u 64p 2u 1u 8p 1u 1u 5p 5p 4u 37p")
if (block_id != b"wvpk"):
from audiotools.text import ERR_WAVPACK_INVALID_HEADER
raise InvalidWavPack(ERR_WAVPACK_INVALID_HEADER)
if (sample_rate != 0xF):
self.__samplerate__ = WavPackAudio.SAMPLING_RATE[sample_rate]
else:
# if unknown, pull from SAMPLE_RATE sub-block
for (block_id,
nondecoder,
data_size,
data) in self.sub_blocks(reader):
if ((block_id == 0x7) and nondecoder):
self.__samplerate__ = data.read(data_size * 8)
break
else:
# no SAMPLE RATE sub-block found
# so pull info from FMT chunk
reader.rewind()
(self.__samplerate__,) = self.fmt_chunk(reader).parse(
"32p 32u")
self.__bitspersample__ = [8, 16, 24, 32][bits_per_sample]
self.__total_frames__ = total_samples
if (initial_block and final_block):
if (mono_output):
self.__channels__ = 1
self.__channel_mask__ = ChannelMask(0x4)
else:
self.__channels__ = 2
self.__channel_mask__ = ChannelMask(0x3)
else:
# if not mono or stereo, pull from CHANNEL INFO sub-block
reader.rewind()
for (block_id,
nondecoder,
data_size,
data) in self.sub_blocks(reader):
if ((block_id == 0xD) and not nondecoder):
self.__channels__ = data.read(8)
self.__channel_mask__ = ChannelMask(
data.read((data_size - 1) * 8))
break
else:
# no CHANNEL INFO sub-block found
# so pull info from FMT chunk
reader.rewind()
fmt = self.fmt_chunk(reader)
compression_code = fmt.read(16)
self.__channels__ = fmt.read(16)
if (compression_code == 1):
# this is theoretically possible
# with very old .wav files,
# but shouldn't happen in practice
self.__channel_mask__ = \
{1: ChannelMask.from_fields(front_center=True),
2: ChannelMask.from_fields(front_left=True,
front_right=True),
3: ChannelMask.from_fields(front_left=True,
front_right=True,
front_center=True),
4: ChannelMask.from_fields(front_left=True,
front_right=True,
back_left=True,
back_right=True),
5: ChannelMask.from_fields(front_left=True,
front_right=True,
back_left=True,
back_right=True,
front_center=True),
6: ChannelMask.from_fields(front_left=True,
front_right=True,
back_left=True,
back_right=True,
front_center=True,
low_frequency=True)
}.get(self.__channels__, ChannelMask(0))
elif (compression_code == 0xFFFE):
fmt.skip(128)
mask = fmt.read(32)
self.__channel_mask__ = ChannelMask(mask)
else:
from audiotools.text import ERR_WAVPACK_UNSUPPORTED_FMT
raise InvalidWavPack(ERR_WAVPACK_UNSUPPORTED_FMT)
finally:
reader.unmark()
reader.close()
class SHNDecoder(object):
def __init__(self, filename):
self.reader = BitstreamReader(open(filename, "rb"), False)
(self.file_type,
self.channels,
self.block_length,
self.max_LPC,
self.number_of_means) = self.read_header()
if (1 <= self.file_type) and (self.file_type <= 2):
self.bits_per_sample = 8
self.signed_samples = (self.file_type == 1)
elif (3 <= self.file_type) and (self.file_type <= 6):
self.bits_per_sample = 16
self.signed_samples = (self.file_type in (3, 5))
else:
raise ValueError("unsupported Shorten file type")
self.wrapped_samples = [[0] * 3 for c in range(self.channels)]
self.means = [[0] * self.number_of_means
for c in range(self.channels)]
self.left_shift = 0
self.stream_finished = False
# try to read the first command for a wave/aiff header
data_start = self.reader.getpos()
self.read_metadata()
self.reader.setpos(data_start)
def read_metadata(self):
from io import BytesIO
command = self.unsigned(2)
if command == 9:
# got verbatim, so read data
verbatim_bytes = ints_to_bytes([self.unsigned(8) & 0xFF
for i in range(self.unsigned(5))])
try:
wave = BitstreamReader(BytesIO(verbatim_bytes), True)
header = wave.read_bytes(12)
if header.startswith(b"RIFF") and header.endswith(b"WAVE"):
# got RIFF/WAVE header, so parse wave blocks as needed
total_size = len(verbatim_bytes) - 12
while total_size > 0:
(chunk_id, chunk_size) = wave.parse("4b 32u")
total_size -= 8
if chunk_id == b'fmt ':
(channels,
self.sample_rate,
bits_per_sample,
channel_mask) = parse_fmt(
wave.substream(chunk_size))
self.channel_mask = int(channel_mask)
return
else:
if chunk_size % 2:
wave.read_bytes(chunk_size + 1)
total_size -= (chunk_size + 1)
else:
wave.read_bytes(chunk_size)
total_size -= chunk_size
else:
# no fmt chunk, so use default metadata
pass
except (IOError, ValueError):
pass
try:
aiff = BitstreamReader(BytesIO(verbatim_bytes), False)
header = aiff.read_bytes(12)
if header.startswith(b"FORM") and header.endswith(b"AIFF"):
# got FORM/AIFF header, so parse aiff blocks as needed
total_size = len(verbatim_bytes) - 12
while total_size > 0:
(chunk_id, chunk_size) = aiff.parse("4b 32u")
total_size -= 8
if chunk_id == b'COMM':
(channels,
total_sample_frames,
bits_per_sample,
self.sample_rate,
channel_mask) = parse_comm(
aiff.substream(chunk_size))
self.channel_mask = int(channel_mask)
return
else:
if chunk_size % 2:
aiff.read_bytes(chunk_size + 1)
total_size -= (chunk_size + 1)
else:
aiff.read_bytes(chunk_size)
total_size -= chunk_size
else:
# no COMM chunk, so use default metadata
pass
except IOError:
pass
# got something else, so invent some PCM parameters
self.sample_rate = 44100
if self.channels == 1:
self.channel_mask = 0x4
elif self.channels == 2:
self.channel_mask = 0x3
else:
self.channel_mask = 0
def unsigned(self, c):
MSB = self.reader.unary(1)
LSB = self.reader.read(c)
return MSB * 2 ** c + LSB
def signed(self, c):
u = self.unsigned(c + 1)
if (u % 2) == 0:
return u // 2
else:
return -(u // 2) - 1
def long(self):
return self.unsigned(self.unsigned(2))
def skip_unsigned(self, c):
self.reader.skip_unary(1)
self.reader.skip(c)
def read_header(self):
magic = self.reader.read_bytes(4)
if magic != b"ajkg":
raise ValueError("invalid magic number")
version = self.reader.read(8)
if version != 2:
raise ValueError("unsupported version")
file_type = self.long()
channels = self.long()
block_length = self.long()
max_LPC = self.long()
number_of_means = self.long()
bytes_to_skip = self.long()
self.reader.read_bytes(bytes_to_skip)
return (file_type, channels, block_length, max_LPC, number_of_means)
def read(self, pcm_frames):
if self.stream_finished:
return from_channels([empty_framelist(1, self.bits_per_sample)
for channel in range(self.channels)])
c = 0
samples = []
unshifted = []
while True:
command = self.unsigned(2)
if (((0 <= command) and (command <= 3) or
(7 <= command) and (command <= 8))):
# audio data commands
if command == 0: # DIFF0
samples.append(self.read_diff0(self.block_length,
self.means[c]))
elif command == 1: # DIFF1
samples.append(self.read_diff1(self.block_length,
self.wrapped_samples[c]))
elif command == 2: # DIFF2
samples.append(self.read_diff2(self.block_length,
self.wrapped_samples[c]))
elif command == 3: # DIFF3
samples.append(self.read_diff3(self.block_length,
self.wrapped_samples[c]))
elif command == 7: # QLPC
samples.append(self.read_qlpc(self.block_length,
self.means[c],
self.wrapped_samples[c]))
elif command == 8: # ZERO
samples.append([0] * self.block_length)
# update means for channel
self.means[c].append(shnmean(samples[c]))
self.means[c] = self.means[c][1:]
# wrap samples for next command in channel
self.wrapped_samples[c] = samples[c][-(max(3, self.max_LPC)):]
# apply left shift to samples
if self.left_shift > 0:
unshifted.append([s << self.left_shift
for s in samples[c]])
else:
unshifted.append(samples[c])
c += 1
if c == self.channels:
# return a FrameList from shifted data
return from_channels([from_list(channel, 1,
self.bits_per_sample,
self.signed_samples)
for channel in unshifted])
else:
# non audio commands
if command == 4: # QUIT
self.stream_finished = True
return from_channels(
[empty_framelist(1, self.bits_per_sample)
for channel in range(self.channels)])
elif command == 5: # BLOCKSIZE
self.block_length = self.long()
elif command == 6: # BITSHIFT
self.left_shift = self.unsigned(2)
elif command == 9: # VERBATIM
# skip this command during reading
size = self.unsigned(5)
for i in range(size):
self.skip_unsigned(8)
else:
raise ValueError("unsupported Shorten command")
def read_diff0(self, block_length, means):
offset = shnmean(means)
energy = self.unsigned(3)
samples = []
for i in range(block_length):
residual = self.signed(energy)
samples.append(residual + offset)
return samples
def read_diff1(self, block_length, previous_samples):
samples = previous_samples[-1:]
energy = self.unsigned(3)
for i in range(1, block_length + 1):
residual = self.signed(energy)
samples.append(samples[i - 1] + residual)
return samples[1:]
def read_diff2(self, block_length, previous_samples):
samples = previous_samples[-2:]
energy = self.unsigned(3)
for i in range(2, block_length + 2):
residual = self.signed(energy)
samples.append((2 * samples[i - 1]) - samples[i - 2] + residual)
return samples[2:]
def read_diff3(self, block_length, previous_samples):
samples = previous_samples[-3:]
energy = self.unsigned(3)
for i in range(3, block_length + 3):
residual = self.signed(energy)
samples.append((3 * (samples[i - 1] - samples[i - 2])) +
samples[i - 3] + residual)
return samples[3:]
def read_qlpc(self, block_length, means, previous_samples):
offset = shnmean(means)
energy = self.unsigned(3)
LPC_count = self.unsigned(2)
LPC_coeff = [self.signed(5) for i in range(LPC_count)]
unoffset = []
samples = previous_samples[-LPC_count:]
for i in range(block_length):
residual = self.signed(energy)
LPC_sum = 2 ** 5
for j in range(LPC_count):
if (i - j - 1) < 0:
# apply offset to warm-up samples
LPC_sum += (LPC_coeff[j] *
(samples[LPC_count + (i - j - 1)] - offset))
else:
LPC_sum += LPC_coeff[j] * unoffset[i - j - 1]
unoffset.append(LPC_sum // 2 ** 5 + residual)
return [u + offset for u in unoffset]
def close(self):
self.reader.close()
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
class WavPackDecoder:
def __init__(self, filename):
self.reader = BitstreamReader(open(filename, "rb"), 1)
#read initial block to populate
#sample_rate, bits_per_sample, channels, and channel_mask
self.reader.mark()
block_header = Block_Header.read(self.reader)
sub_blocks_size = block_header.block_size - 24
sub_blocks_data = self.reader.substream(sub_blocks_size)
if (block_header.sample_rate != 15):
self.sample_rate = [6000, 8000, 9600, 11025, 12000,
16000, 22050, 24000, 32000, 44100,
48000, 64000, 88200, 96000,
192000][block_header.sample_rate]
else:
sub_blocks_data.mark()
try:
for sub_block in sub_blocks(sub_blocks_data, sub_blocks_size):
if ((sub_block.metadata_function == 7) and
(sub_block.nondecoder_data == 1)):
self.sample_rate = sub_block.data.read(
sub_block.data_size() * 8)
break
else:
raise ValueError("invalid sample rate")
finally:
sub_blocks_data.rewind()
sub_blocks_data.unmark()
self.bits_per_sample = [8, 16, 24, 32][block_header.bits_per_sample]
if (block_header.initial_block and block_header.final_block):
if ((block_header.mono_output == 0) or
(block_header.false_stereo == 1)):
self.channels = 2
self.channel_mask = 0x3
else:
self.channels = 1
self.channel_mask = 0x4
else:
#look for channel mask sub block
sub_blocks_data.mark()
for sub_block in sub_blocks(sub_blocks_data, sub_blocks_size):
if ((sub_block.metadata_function == 13) and
(sub_block.nondecoder_data == 0)):
self.channels = sub_block.data.read(8)
self.channel_mask = sub_block.data.read(
(sub_block.data_size() - 1) * 8)
break
else:
#FIXME - handle case of no channel mask sub block
raise NotImplementedError()
sub_blocks_data.rewind()
sub_blocks_data.unmark()
self.reader.rewind()
self.reader.unmark()
self.pcm_finished = False
self.md5_checked = False
self.md5sum = md5()
def read(self, bytes):
if (self.pcm_finished):
if (not self.md5_checked):
self.reader.mark()
try:
try:
header = Block_Header.read(self.reader)
sub_blocks_size = header.block_size - 24
sub_blocks_data = self.reader.substream(sub_blocks_size)
for sub_block in sub_blocks(sub_blocks_data,
sub_blocks_size):
if ((sub_block.metadata_function == 6) and
(sub_block.nondecoder_data == 1)):
if (sub_block.data.read_bytes(16) !=
self.md5sum.digest()):
raise ValueError("invalid stream MD5 sum")
except (IOError, ValueError):
#no error if a block isn't found
pass
finally:
self.reader.rewind()
self.reader.unmark()
return from_list([], self.channels, self.bits_per_sample, True)
channels = []
while (True): #in place of a do-while loop
try:
block_header = Block_Header.read(self.reader)
except (ValueError, IOError):
self.pcm_finished = True
return from_list([], self.channels, self.bits_per_sample, True)
sub_blocks_size = block_header.block_size - 24
sub_blocks_data = self.reader.substream(sub_blocks_size)
channels.extend(read_block(block_header,
sub_blocks_size,
sub_blocks_data))
if (block_header.final_block == 1):
break
if ((block_header.block_index + block_header.block_samples) >=
block_header.total_samples):
self.pcm_finished = True
#combine channels of audio data into single block
block = from_channels([from_list(ch, 1, self.bits_per_sample, True)
for ch in channels])
#update MD5 sum
self.md5sum.update(block.to_bytes(False, self.bits_per_sample > 8))
#return single block of audio data
return block
def close(self):
self.reader.close()
def aiff_header_footer(self):
"""returns (header, footer) tuple of strings
containing all data before and after the PCM stream
if self.has_foreign_aiff_chunks() is False,
may raise ValueError if the file has no header and footer
for any reason"""
from audiotools.bitstream import BitstreamReader
from audiotools.bitstream import BitstreamRecorder
from audiotools.text import (ERR_AIFF_NOT_AIFF, ERR_AIFF_INVALID_AIFF,
ERR_AIFF_INVALID_CHUNK_ID)
head = BitstreamRecorder(0)
tail = BitstreamRecorder(0)
current_block = head
aiff_file = BitstreamReader(open(self.filename, 'rb'), 0)
try:
# transfer the 12-byte "RIFFsizeWAVE" header to head
(form, size, aiff) = aiff_file.parse("4b 32u 4b")
if (form != 'FORM'):
raise InvalidAIFF(ERR_AIFF_NOT_AIFF)
elif (aiff != 'AIFF'):
raise InvalidAIFF(ERR_AIFF_INVALID_AIFF)
else:
current_block.build("4b 32u 4b", (form, size, aiff))
total_size = size - 4
while (total_size > 0):
# transfer each chunk header
(chunk_id, chunk_size) = aiff_file.parse("4b 32u")
if (not frozenset(chunk_id).issubset(self.PRINTABLE_ASCII)):
raise InvalidAIFF(ERR_AIFF_INVALID_CHUNK_ID)
else:
current_block.build("4b 32u", (chunk_id, chunk_size))
total_size -= 8
# and transfer the full content of non-audio chunks
if (chunk_id != "SSND"):
if (chunk_size % 2):
current_block.write_bytes(
aiff_file.read_bytes(chunk_size + 1))
total_size -= (chunk_size + 1)
else:
current_block.write_bytes(
aiff_file.read_bytes(chunk_size))
total_size -= chunk_size
else:
# transfer alignment as part of SSND's chunk header
align = aiff_file.parse("32u 32u")
current_block.build("32u 32u", align)
aiff_file.skip_bytes(chunk_size - 8)
current_block = tail
if (chunk_size % 2):
current_block.write_bytes(aiff_file.read_bytes(1))
total_size -= (chunk_size + 1)
else:
total_size -= chunk_size
return (head.data(), tail.data())
finally:
aiff_file.close()