def tags(file, order):
while True:
reader = BitstreamReader(file, order)
# read all the tags in an IFD
tag_count = reader.read(16)
sub_reader = reader.substream(tag_count * 12)
next_ifd = reader.read(32)
for i in range(tag_count):
(tag_code,
tag_datatype,
tag_value_count) = sub_reader.parse("16u 16u 32u")
if tag_datatype == 1: # BYTE type
tag_struct = "8u" * tag_value_count
elif tag_datatype == 3: # SHORT type
tag_struct = "16u" * tag_value_count
elif tag_datatype == 4: # LONG type
tag_struct = "32u" * tag_value_count
else: # all other types
tag_struct = "4b"
if format_size(tag_struct) <= 32:
yield (tag_code, sub_reader.parse(tag_struct))
sub_reader.skip(32 - format_size(tag_struct))
else:
offset = sub_reader.read(32)
file.seek(offset, 0)
yield (tag_code,
BitstreamReader(file, order).parse(tag_struct))
if next_ifd != 0:
file.seek(next_ifd, 0)
else:
break
def tags(file, order):
while True:
reader = BitstreamReader(file, order)
# read all the tags in an IFD
tag_count = reader.read(16)
sub_reader = reader.substream(tag_count * 12)
next_ifd = reader.read(32)
for i in range(tag_count):
(tag_code, tag_datatype,
tag_value_count) = sub_reader.parse("16u 16u 32u")
if tag_datatype == 1: # BYTE type
tag_struct = "8u" * tag_value_count
elif tag_datatype == 3: # SHORT type
tag_struct = "16u" * tag_value_count
elif tag_datatype == 4: # LONG type
tag_struct = "32u" * tag_value_count
else: # all other types
tag_struct = "4b"
if format_size(tag_struct) <= 32:
yield (tag_code, sub_reader.parse(tag_struct))
sub_reader.skip(32 - format_size(tag_struct))
else:
offset = sub_reader.read(32)
file.seek(offset, 0)
yield (tag_code,
BitstreamReader(file, order).parse(tag_struct))
if next_ifd != 0:
file.seek(next_ifd, 0)
else:
break
def get_metadata(self):
"""returns a MetaData object, or None
raises IOError if unable to read the file"""
from cStringIO import StringIO
from audiotools.bitstream import BitstreamReader
from audiotools.ogg import PacketReader, PageReader
from audiotools.vorbiscomment import VorbisComment
reader = PacketReader(PageReader(open(self.filename, "rb")))
identification = reader.read_packet()
comment = BitstreamReader(StringIO(reader.read_packet()), True)
(packet_type, packet_header) = comment.parse("8u 6b")
if ((packet_type == 3) and (packet_header == 'vorbis')):
vendor_string = \
comment.read_bytes(comment.read(32)).decode('utf-8')
comment_strings = [
comment.read_bytes(comment.read(32)).decode('utf-8')
for i in xrange(comment.read(32))]
if (comment.read(1) == 1): # framing bit
return VorbisComment(comment_strings, vendor_string)
else:
return None
else:
return None
def get_replay_gain(self):
"""returns a ReplayGain object of our ReplayGain values
returns None if we have no values
may raise IOError if unable to read the file"""
from audiotools import ReplayGain
try:
rg = BitstreamReader(self.get_block(b"RG"), False)
except KeyError:
return None
version = rg.read(8)
if version != 1:
return None
gain_title = rg.read(16)
peak_title = rg.read(16)
gain_album = rg.read(16)
peak_album = rg.read(16)
if ((gain_title == 0) and (peak_title == 0) and
(gain_album == 0) and (peak_album == 0)):
return None
else:
return ReplayGain(
track_gain=64.82 - float(gain_title) / 256,
track_peak=(10 ** (float(peak_title) / 256 / 20)) / 2 ** 15,
album_gain=64.82 - float(gain_album) / 256,
album_peak=(10 ** (float(peak_album) / 256 / 20)) / 2 ** 15)
def get_metadata(self):
"""returns a MetaData object, or None
raises IOError if unable to read the file"""
from io import BytesIO
from audiotools.bitstream import BitstreamReader
from audiotools.ogg import PacketReader, PageReader
reader = PacketReader(PageReader(open(self.filename, "rb")))
identification = reader.read_packet()
comment = BitstreamReader(BytesIO(reader.read_packet()), True)
if (comment.read_bytes(8) == "OpusTags"):
vendor_string = \
comment.read_bytes(comment.read(32)).decode('utf-8')
comment_strings = [
comment.read_bytes(comment.read(32)).decode('utf-8')
for i in range(comment.read(32))
]
return VorbisComment(comment_strings, vendor_string)
else:
return None
def get_replay_gain(self):
"""returns a ReplayGain object of our ReplayGain values
returns None if we have no values
may raise IOError if unable to read the file"""
from audiotools import ReplayGain
try:
rg = BitstreamReader(self.get_block(b"RG"), False)
except KeyError:
return None
version = rg.read(8)
if version != 1:
return None
gain_title = rg.read(16)
peak_title = rg.read(16)
gain_album = rg.read(16)
peak_album = rg.read(16)
if ((gain_title == 0) and (peak_title == 0) and (gain_album == 0)
and (peak_album == 0)):
return None
else:
return ReplayGain(
track_gain=64.82 - float(gain_title) / 256,
track_peak=(10**(float(peak_title) / 256 / 20)) / 2**15,
album_gain=64.82 - float(gain_album) / 256,
album_peak=(10**(float(peak_album) / 256 / 20)) / 2**15)
def __read_identification__(self):
from .bitstream import BitstreamReader
f = open(self.filename, "rb")
try:
ogg_reader = BitstreamReader(f, 1)
(magic_number,
version,
header_type,
granule_position,
self.__serial_number__,
page_sequence_number,
checksum,
segment_count) = ogg_reader.parse("4b 8u 8u 64S 32u 32u 32u 8u")
if (magic_number != 'OggS'):
from .text import ERR_OGG_INVALID_MAGIC_NUMBER
raise InvalidFLAC(ERR_OGG_INVALID_MAGIC_NUMBER)
if (version != 0):
from .text import ERR_OGG_INVALID_VERSION
raise InvalidFLAC(ERR_OGG_INVALID_VERSION)
segment_length = ogg_reader.read(8)
(vorbis_type,
header,
version,
self.__channels__,
self.__sample_rate__,
maximum_bitrate,
nominal_bitrate,
minimum_bitrate,
blocksize0,
blocksize1,
framing) = ogg_reader.parse(
"8u 6b 32u 8u 32u 32u 32u 32u 4u 4u 1u")
if (vorbis_type != 1):
from .text import ERR_VORBIS_INVALID_TYPE
raise InvalidVorbis(ERR_VORBIS_INVALID_TYPE)
if (header != 'vorbis'):
from .text import ERR_VORBIS_INVALID_HEADER
raise InvalidVorbis(ERR_VORBIS_INVALID_HEADER)
if (version != 0):
from .text import ERR_VORBIS_INVALID_VERSION
raise InvalidVorbis(ERR_VORBIS_INVALID_VERSION)
if (framing != 1):
from .text import ERR_VORBIS_INVALID_FRAMING_BIT
raise InvalidVorbis(ERR_VORBIS_INVALID_FRAMING_BIT)
finally:
f.close()
def get_metadata(self):
"""returns a MetaData object, or None
raises IOError if unable to read the file"""
from io import BytesIO
from audiotools.bitstream import BitstreamReader
from audiotools.ogg import PacketReader, PageReader
from audiotools.vorbiscomment import VorbisComment
with PacketReader(PageReader(open(self.filename, "rb"))) as reader:
identification = reader.read_packet()
comment = BitstreamReader(BytesIO(reader.read_packet()), True)
vendor_string = \
comment.read_bytes(comment.read(32)).decode('utf-8')
comment_strings = [
comment.read_bytes(comment.read(32)).decode('utf-8')
for i in range(comment.read(32))]
return VorbisComment(comment_strings, vendor_string)
def get_metadata(self):
"""returns a MetaData object, or None
raises IOError if unable to read the file"""
from audiotools.ogg import PacketReader,PageReader
from cStringIO import StringIO
from audiotools.bitstream import BitstreamReader
packets = PacketReader(PageReader(open(self.filename, "rb")))
identification = packets.read_packet()
comment = BitstreamReader(StringIO(packets.read_packet()), True)
if (comment.read_bytes(8) == "OpusTags"):
vendor_string = \
comment.read_bytes(comment.read(32)).decode('utf-8')
comment_strings = [
comment.read_bytes(comment.read(32)).decode('utf-8')
for i in xrange(comment.read(32))]
return VorbisComment(comment_strings, vendor_string)
else:
return None
def __init__(self, filename):
"""filename is a plain string"""
AudioFile.__init__(self, filename)
try:
block = BitstreamReader(self.get_block(b"SH"), False)
crc = block.read(32)
if block.read(8) != 8:
from audiotools.text import ERR_MPC_INVALID_VERSION
raise InvalidMPC(ERR_MPC_INVALID_VERSION)
self.__samples__ = int(MPC_Size.parse(block))
beg_silence = int(MPC_Size.parse(block))
self.__sample_rate__ = \
[44100, 48000, 37800, 32000][block.read(3)]
max_band = block.read(5) + 1
self.__channels__ = block.read(4) + 1
ms = block.read(1)
block_pwr = block.read(3) * 2
except IOError as err:
raise InvalidMPC(str(err))
def __init__(self, filename):
"""filename is a plain string"""
AudioFile.__init__(self, filename)
try:
block = BitstreamReader(self.get_block(b"SH"), False)
crc = block.read(32)
if block.read(8) != 8:
from audiotools.text import ERR_MPC_INVALID_VERSION
raise InvalidMPC(ERR_MPC_INVALID_VERSION)
self.__samples__ = int(MPC_Size.parse(block))
beg_silence = int(MPC_Size.parse(block))
self.__sample_rate__ = \
[44100, 48000, 37800, 32000][block.read(3)]
max_band = block.read(5) + 1
self.__channels__ = block.read(4) + 1
ms = block.read(1)
block_pwr = block.read(3) * 2
except IOError as err:
raise InvalidMPC(str(err))
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()
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 __parse_info__(self):
"""generates a cache of sample_rate, bits-per-sample, etc"""
import re
import os.path
from audiotools.bitstream import BitstreamReader
if (len(self.tracks) == 0):
return
# Why is this post-init processing necessary?
# DVDATrack references DVDATitle
# so a DVDATitle must exist when DVDATrack is initialized.
# But because reading this info requires knowing the sector
# of the first track, we wind up with a circular dependency.
# Doing a "post-process" pass fixes that problem.
# find the AOB file of the title's first track
track_sector = self[0].first_sector
titleset = re.compile("ATS_%2.2d_\\d\\.AOB" % (self.titleset))
for aob_path in sorted([self.dvdaudio.files[key] for key in
self.dvdaudio.files.keys()
if (titleset.match(key))]):
aob_sectors = os.path.getsize(aob_path) // DVDAudio.SECTOR_SIZE
if (track_sector > aob_sectors):
track_sector -= aob_sectors
else:
break
else:
from audiotools.text import ERR_DVDA_NO_TRACK_SECTOR
raise ValueError(ERR_DVDA_NO_TRACK_SECTOR)
# open that AOB file and seek to that track's first sector
aob_file = open(aob_path, 'rb')
try:
aob_file.seek(track_sector * DVDAudio.SECTOR_SIZE)
aob_reader = BitstreamReader(aob_file, 0)
# read and validate the pack header
# (there's one pack header per sector, at the sector's start)
(sync_bytes,
marker1,
current_pts_high,
marker2,
current_pts_mid,
marker3,
current_pts_low,
marker4,
scr_extension,
marker5,
bit_rate,
marker6,
stuffing_length) = aob_reader.parse(
"32u 2u 3u 1u 15u 1u 15u 1u 9u 1u 22u 2u 5p 3u")
aob_reader.skip_bytes(stuffing_length)
if (sync_bytes != 0x1BA):
from audiotools.text import ERR_DVDA_INVALID_AOB_SYNC
raise InvalidDVDA(ERR_DVDA_INVALID_AOB_SYNC)
if (((marker1 != 1) or (marker2 != 1) or (marker3 != 1) or
(marker4 != 1) or (marker5 != 1) or (marker6 != 3))):
from audiotools.text import ERR_DVDA_INVALID_AOB_MARKER
raise InvalidDVDA(ERR_DVDA_INVALID_AOB_MARKER)
packet_pts = ((current_pts_high << 30) |
(current_pts_mid << 15) |
current_pts_low)
# skip packets until one with a stream ID of 0xBD is found
(start_code,
stream_id,
packet_length) = aob_reader.parse("24u 8u 16u")
if (start_code != 1):
from audiotools.text import ERR_DVDA_INVALID_AOB_START
raise InvalidDVDA(ERR_DVDA_INVALID_AOB_START)
while (stream_id != 0xBD):
aob_reader.skip_bytes(packet_length)
(start_code,
stream_id,
packet_length) = aob_reader.parse("24u 8u 16u")
if (start_code != 1):
from audiotools.text import ERR_DVDA_INVALID_AOB_START
raise InvalidDVDA(ERR_DVDA_INVALID_AOB_START)
# parse the PCM/MLP header in the packet data
(pad1_size,) = aob_reader.parse("16p 8u")
aob_reader.skip_bytes(pad1_size)
(stream_id, crc) = aob_reader.parse("8u 8u 8p")
if (stream_id == 0xA0): # PCM
# read a PCM reader
(pad2_size,
first_audio_frame,
padding2,
group1_bps,
group2_bps,
group1_sample_rate,
group2_sample_rate,
padding3,
channel_assignment) = aob_reader.parse(
"8u 16u 8u 4u 4u 4u 4u 8u 8u")
else: # MLP
aob_reader.skip_bytes(aob_reader.read(8)) # skip pad2
# read a total frame size + MLP major sync header
(total_frame_size,
sync_words,
stream_type,
group1_bps,
group2_bps,
group1_sample_rate,
group2_sample_rate,
unknown1,
channel_assignment,
unknown2) = aob_reader.parse(
"4p 12u 16p 24u 8u 4u 4u 4u 4u 11u 5u 48u")
# return the values indicated by the header
self.sample_rate = DVDATrack.SAMPLE_RATE[group1_sample_rate]
self.channels = DVDATrack.CHANNELS[channel_assignment]
self.channel_mask = DVDATrack.CHANNEL_MASK[channel_assignment]
self.bits_per_sample = DVDATrack.BITS_PER_SAMPLE[group1_bps]
self.stream_id = stream_id
finally:
aob_file.close()
class ALACDecoder:
def __init__(self, filename):
self.reader = BitstreamReader(open(filename, "rb"), 0)
self.reader.mark()
try:
#locate the "alac" atom
#which is full of required decoding parameters
try:
stsd = self.find_sub_atom("moov", "trak", "mdia",
"minf", "stbl", "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 != 'alac') or (alac2 != '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("moov", "trak", "mdia", "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 != "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 from_list([], self.channels, self.bits_per_sample, True)
#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 xrange(sample_count * channel_count)]
return [samples[i::channel_count] for i in xrange(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 xrange(channel_count)]
#optional uncompressed LSB values
if (uncompressed_lsb_size > 0):
uncompressed_lsbs = [
self.reader.read(uncompressed_lsb_size * 8)
for i in xrange(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 xrange(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 xrange(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.limited_unary(0, 9)
if (msb is None):
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 xrange(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):
pass
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 FrameList("", self.channels, self.bits_per_sample, True,
True)
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):
# FIXME
pass
def parse(cls, file_data):
from io import BytesIO
def tags(file, order):
while True:
reader = BitstreamReader(file, order)
# read all the tags in an IFD
tag_count = reader.read(16)
sub_reader = reader.substream(tag_count * 12)
next_ifd = reader.read(32)
for i in range(tag_count):
(tag_code,
tag_datatype,
tag_value_count) = sub_reader.parse("16u 16u 32u")
if tag_datatype == 1: # BYTE type
tag_struct = "8u" * tag_value_count
elif tag_datatype == 3: # SHORT type
tag_struct = "16u" * tag_value_count
elif tag_datatype == 4: # LONG type
tag_struct = "32u" * tag_value_count
else: # all other types
tag_struct = "4b"
if format_size(tag_struct) <= 32:
yield (tag_code, sub_reader.parse(tag_struct))
sub_reader.skip(32 - format_size(tag_struct))
else:
offset = sub_reader.read(32)
file.seek(offset, 0)
yield (tag_code,
BitstreamReader(file, order).parse(tag_struct))
if next_ifd != 0:
file.seek(next_ifd, 0)
else:
break
file = BytesIO(file_data)
try:
byte_order = file.read(2)
if byte_order == b'II':
order = 1
elif byte_order == b'MM':
order = 0
else:
from audiotools.text import ERR_IMAGE_INVALID_TIFF
raise InvalidTIFF(ERR_IMAGE_INVALID_TIFF)
reader = BitstreamReader(file, order)
if reader.read(16) != 42:
from audiotools.text import ERR_IMAGE_INVALID_TIFF
raise InvalidTIFF(ERR_IMAGE_INVALID_TIFF)
initial_ifd = reader.read(32)
file.seek(initial_ifd, 0)
width = 0
height = 0
bits_per_pixel = 0
color_count = 0
for (tag_id, tag_values) in tags(file, order):
if tag_id == 0x0100:
width = tag_values[0]
elif tag_id == 0x0101:
height = tag_values[0]
elif tag_id == 0x0102:
bits_per_pixel = sum(tag_values)
elif tag_id == 0x0140:
color_count = len(tag_values) // 3
except IOError:
from audiotools.text import ERR_IMAGE_IOERROR_TIFF
raise InvalidTIFF(ERR_IMAGE_IOERROR_TIFF)
return cls(width=width,
height=height,
bits_per_pixel=bits_per_pixel,
color_count=color_count)
def parse(cls, file_data):
from io import BytesIO
def tags(file, order):
while True:
reader = BitstreamReader(file, order)
# read all the tags in an IFD
tag_count = reader.read(16)
sub_reader = reader.substream(tag_count * 12)
next_ifd = reader.read(32)
for i in range(tag_count):
(tag_code, tag_datatype,
tag_value_count) = sub_reader.parse("16u 16u 32u")
if tag_datatype == 1: # BYTE type
tag_struct = "8u" * tag_value_count
elif tag_datatype == 3: # SHORT type
tag_struct = "16u" * tag_value_count
elif tag_datatype == 4: # LONG type
tag_struct = "32u" * tag_value_count
else: # all other types
tag_struct = "4b"
if format_size(tag_struct) <= 32:
yield (tag_code, sub_reader.parse(tag_struct))
sub_reader.skip(32 - format_size(tag_struct))
else:
offset = sub_reader.read(32)
file.seek(offset, 0)
yield (tag_code,
BitstreamReader(file, order).parse(tag_struct))
if next_ifd != 0:
file.seek(next_ifd, 0)
else:
break
file = BytesIO(file_data)
try:
byte_order = file.read(2)
if byte_order == b'II':
order = 1
elif byte_order == b'MM':
order = 0
else:
from audiotools.text import ERR_IMAGE_INVALID_TIFF
raise InvalidTIFF(ERR_IMAGE_INVALID_TIFF)
reader = BitstreamReader(file, order)
if reader.read(16) != 42:
from audiotools.text import ERR_IMAGE_INVALID_TIFF
raise InvalidTIFF(ERR_IMAGE_INVALID_TIFF)
initial_ifd = reader.read(32)
file.seek(initial_ifd, 0)
width = 0
height = 0
bits_per_pixel = 0
color_count = 0
for (tag_id, tag_values) in tags(file, order):
if tag_id == 0x0100:
width = tag_values[0]
elif tag_id == 0x0101:
height = tag_values[0]
elif tag_id == 0x0102:
bits_per_pixel = sum(tag_values)
elif tag_id == 0x0140:
color_count = len(tag_values) // 3
except IOError:
from audiotools.text import ERR_IMAGE_IOERROR_TIFF
raise InvalidTIFF(ERR_IMAGE_IOERROR_TIFF)
return cls(width=width,
height=height,
bits_per_pixel=bits_per_pixel,
color_count=color_count)
class TTADecoder:
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
xrange(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 FrameList("",
self.channels,
self.bits_per_sample,
True,
True)
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 xrange(self.channels)]
for f in xrange(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):
#FIXME
pass
def __parse_info__(self):
"""generates a cache of sample_rate, bits-per-sample, etc"""
import re
import os.path
from audiotools.bitstream import BitstreamReader
if (len(self.tracks) == 0):
return
# Why is this post-init processing necessary?
# DVDATrack references DVDATitle
# so a DVDATitle must exist when DVDATrack is initialized.
# But because reading this info requires knowing the sector
# of the first track, we wind up with a circular dependency.
# Doing a "post-process" pass fixes that problem.
# find the AOB file of the title's first track
track_sector = self[0].first_sector
titleset = re.compile("ATS_%2.2d_\\d\\.AOB" % (self.titleset))
for aob_path in sorted([
self.dvdaudio.files[key] for key in self.dvdaudio.files.keys()
if (titleset.match(key))
]):
aob_sectors = os.path.getsize(aob_path) // DVDAudio.SECTOR_SIZE
if (track_sector > aob_sectors):
track_sector -= aob_sectors
else:
break
else:
from audiotools.text import ERR_DVDA_NO_TRACK_SECTOR
raise ValueError(ERR_DVDA_NO_TRACK_SECTOR)
# open that AOB file and seek to that track's first sector
aob_file = open(aob_path, 'rb')
try:
aob_file.seek(track_sector * DVDAudio.SECTOR_SIZE)
aob_reader = BitstreamReader(aob_file, 0)
# read and validate the pack header
# (there's one pack header per sector, at the sector's start)
(sync_bytes, marker1, current_pts_high, marker2, current_pts_mid,
marker3, current_pts_low, marker4, scr_extension, marker5,
bit_rate, marker6, stuffing_length) = aob_reader.parse(
"32u 2u 3u 1u 15u 1u 15u 1u 9u 1u 22u 2u 5p 3u")
aob_reader.skip_bytes(stuffing_length)
if (sync_bytes != 0x1BA):
from audiotools.text import ERR_DVDA_INVALID_AOB_SYNC
raise InvalidDVDA(ERR_DVDA_INVALID_AOB_SYNC)
if (((marker1 != 1) or (marker2 != 1) or (marker3 != 1)
or (marker4 != 1) or (marker5 != 1) or (marker6 != 3))):
from audiotools.text import ERR_DVDA_INVALID_AOB_MARKER
raise InvalidDVDA(ERR_DVDA_INVALID_AOB_MARKER)
packet_pts = ((current_pts_high << 30) | (current_pts_mid << 15)
| current_pts_low)
# skip packets until one with a stream ID of 0xBD is found
(start_code, stream_id,
packet_length) = aob_reader.parse("24u 8u 16u")
if (start_code != 1):
from audiotools.text import ERR_DVDA_INVALID_AOB_START
raise InvalidDVDA(ERR_DVDA_INVALID_AOB_START)
while (stream_id != 0xBD):
aob_reader.skip_bytes(packet_length)
(start_code, stream_id,
packet_length) = aob_reader.parse("24u 8u 16u")
if (start_code != 1):
from audiotools.text import ERR_DVDA_INVALID_AOB_START
raise InvalidDVDA(ERR_DVDA_INVALID_AOB_START)
# parse the PCM/MLP header in the packet data
(pad1_size, ) = aob_reader.parse("16p 8u")
aob_reader.skip_bytes(pad1_size)
(stream_id, crc) = aob_reader.parse("8u 8u 8p")
if (stream_id == 0xA0): # PCM
# read a PCM reader
(pad2_size, first_audio_frame, padding2, group1_bps,
group2_bps, group1_sample_rate, group2_sample_rate, padding3,
channel_assignment
) = aob_reader.parse("8u 16u 8u 4u 4u 4u 4u 8u 8u")
else: # MLP
aob_reader.skip_bytes(aob_reader.read(8)) # skip pad2
# read a total frame size + MLP major sync header
(total_frame_size, sync_words, stream_type, group1_bps,
group2_bps, group1_sample_rate, group2_sample_rate, unknown1,
channel_assignment, unknown2) = aob_reader.parse(
"4p 12u 16p 24u 8u 4u 4u 4u 4u 11u 5u 48u")
# return the values indicated by the header
self.sample_rate = DVDATrack.SAMPLE_RATE[group1_sample_rate]
self.channels = DVDATrack.CHANNELS[channel_assignment]
self.channel_mask = DVDATrack.CHANNEL_MASK[channel_assignment]
self.bits_per_sample = DVDATrack.BITS_PER_SAMPLE[group1_bps]
self.stream_id = stream_id
finally:
aob_file.close()
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()
def __init__(self, filename):
"""filename is a plain string"""
AudioFile.__init__(self, filename)
self.__channels__ = 0
self.__channel_mask__ = 0
#get channel count and channel mask from first packet
from .bitstream import BitstreamReader
try:
f = open(filename, "rb")
try:
ogg_reader = BitstreamReader(f, 1)
(magic_number,
version,
header_type,
granule_position,
self.__serial_number__,
page_sequence_number,
checksum,
segment_count) = ogg_reader.parse(
"4b 8u 8u 64S 32u 32u 32u 8u")
if (magic_number != 'OggS'):
from .text import ERR_OGG_INVALID_MAGIC_NUMBER
raise InvalidFLAC(ERR_OGG_INVALID_MAGIC_NUMBER)
if (version != 0):
from .text import ERR_OGG_INVALID_VERSION
raise InvalidFLAC(ERR_OGG_INVALID_VERSION)
segment_length = ogg_reader.read(8)
(opushead,
version,
self.__channels__,
pre_skip,
input_sample_rate,
output_gain,
mapping_family) = ogg_reader.parse(
"8b 8u 8u 16u 32u 16s 8u")
if (opushead != "OpusHead"):
from .text import ERR_OPUS_INVALID_TYPE
raise InvalidOpus(ERR_OPUS_INVALID_TYPE)
if (version != 1):
from .text import ERR_OPUS_INVALID_VERSION
raise InvalidOpus(ERR_OPUS_INVALID_VERSION)
if (self.__channels__ == 0):
from .text import ERR_OPUS_INVALID_CHANNELS
raise InvalidOpus(ERR_OPUS_INVALID_CHANNELS)
#FIXME - assign channel mask from mapping family
if (mapping_family == 0):
if (self.__channels__ == 1):
self.__channel_mask__ = VorbisChannelMask(0x4)
elif (self.__channels__ == 2):
self.__channel_mask__ = VorbisChannelMask(0x3)
else:
self.__channel_mask__ = VorbisChannelMask(0)
else:
(stream_count,
coupled_stream_count) = ogg_reader.parse("8u 8u")
if (self.__channels__ !=
((coupled_stream_count * 2) +
(stream_count - coupled_stream_count))):
from .text import ERR_OPUS_INVALID_CHANNELS
raise InvalidOpus(ERR_OPUS_INVALID_CHANNELS)
channel_mapping = [ogg_reader.read(8)
for i in xrange(self.__channels__)]
finally:
f.close()
except IOError, msg:
raise InvalidOpus(str(msg))
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()
def __init__(self, filename):
"""filename is a plain string"""
AudioFile.__init__(self, filename)
self.__channels__ = 0
self.__channel_mask__ = 0
# get channel count and channel mask from first packet
from audiotools.bitstream import BitstreamReader
try:
f = open(filename, "rb")
try:
ogg_reader = BitstreamReader(f, 1)
(magic_number, version, header_type, granule_position,
self.__serial_number__, page_sequence_number, checksum,
segment_count
) = ogg_reader.parse("4b 8u 8u 64S 32u 32u 32u 8u")
if (magic_number != 'OggS'):
from audiotools.text import ERR_OGG_INVALID_MAGIC_NUMBER
raise InvalidOpus(ERR_OGG_INVALID_MAGIC_NUMBER)
if (version != 0):
from audiotools.text import ERR_OGG_INVALID_VERSION
raise InvalidOpus(ERR_OGG_INVALID_VERSION)
segment_length = ogg_reader.read(8)
(opushead, version, self.__channels__, pre_skip,
input_sample_rate, output_gain,
mapping_family) = ogg_reader.parse("8b 8u 8u 16u 32u 16s 8u")
if (opushead != "OpusHead"):
from audiotools.text import ERR_OPUS_INVALID_TYPE
raise InvalidOpus(ERR_OPUS_INVALID_TYPE)
if (version != 1):
from audiotools.text import ERR_OPUS_INVALID_VERSION
raise InvalidOpus(ERR_OPUS_INVALID_VERSION)
if (self.__channels__ == 0):
from audiotools.text import ERR_OPUS_INVALID_CHANNELS
raise InvalidOpus(ERR_OPUS_INVALID_CHANNELS)
# FIXME - assign channel mask from mapping family
if (mapping_family == 0):
if (self.__channels__ == 1):
self.__channel_mask__ = VorbisChannelMask(0x4)
elif (self.__channels__ == 2):
self.__channel_mask__ = VorbisChannelMask(0x3)
else:
self.__channel_mask__ = VorbisChannelMask(0)
else:
(stream_count,
coupled_stream_count) = ogg_reader.parse("8u 8u")
if (self.__channels__ !=
((coupled_stream_count * 2) +
(stream_count - coupled_stream_count))):
from audiotools.text import ERR_OPUS_INVALID_CHANNELS
raise InvalidOpus(ERR_OPUS_INVALID_CHANNELS)
channel_mapping = [
ogg_reader.read(8) for i in range(self.__channels__)
]
finally:
f.close()
except IOError as msg:
raise InvalidOpus(str(msg))
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()
