def read(self, bytes):
"""Try to read a pcm.FrameList of size "bytes"."""
#convert bytes to a number of PCM frames
frames_read = min(max(bytes / self.bytes_per_frame, 1),
self.remaining_frames)
if (frames_read > 0):
pcm_data = self.file.read(frames_read * self.bytes_per_frame)
if (len(pcm_data) < frames_read * self.bytes_per_frame):
raise IOError("ssnd chunk ends prematurely")
else:
framelist = pcm.FrameList(pcm_data,
self.channels,
self.bits_per_sample,
True, True)
self.remaining_frames -= framelist.frames
if (self.channel_order is not None):
return pcm.from_channels(
[framelist.channel(channel) for channel
in self.channel_order])
else:
return framelist
else:
return pcm.FrameList("",
self.channels,
self.bits_per_sample,
True, True)
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(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 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 read(self, bytes):
"""Try to read a pcm.FrameList of size "bytes"."""
#align bytes downward if an odd number is read in
bytes -= (bytes % (self.channels * self.bits_per_sample / 8))
pcm_data = self.file.read(
max(bytes, self.channels * self.bits_per_sample / 8))
if ((len(pcm_data) == 0) and (self.ssnd_chunk_length > 0)):
raise IOError("ssnd chunk ends prematurely")
else:
self.ssnd_chunk_length -= len(pcm_data)
try:
framelist = pcm.FrameList(pcm_data,
self.channels,
self.bits_per_sample,
True, True)
if (self.channel_order is not None):
return pcm.from_channels([framelist.channel(channel)
for channel in self.channel_order])
else:
return framelist
except ValueError:
raise IOError("ssnd chunk ends prematurely")
def read(self, bytes):
"""Try to read a pcm.FrameList of size "bytes"."""
#align bytes downward if an odd number is read in
bytes -= (bytes % (self.channels * self.bits_per_sample / 8))
pcm_data = self.file.read(
max(bytes, self.channels * self.bits_per_sample / 8))
if ((len(pcm_data) == 0) and (self.ssnd_chunk_length > 0)):
raise IOError("ssnd chunk ends prematurely")
else:
self.ssnd_chunk_length -= len(pcm_data)
try:
framelist = pcm.FrameList(pcm_data, self.channels,
self.bits_per_sample, True, True)
if (self.channel_order is not None):
return pcm.from_channels([
framelist.channel(channel)
for channel in self.channel_order
])
else:
return framelist
except ValueError:
raise IOError("ssnd chunk ends prematurely")
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(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 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(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 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")
