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Issue #19641: Added the audioop.byteswap() function to convert big-endian

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samples to little-endian and vice versa.
This commit is contained in:
Serhiy Storchaka 2013-11-23 22:26:01 +02:00
parent 2b38fc187c
commit 3062c9a6c8
10 changed files with 80 additions and 78 deletions
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51
Lib/wave.py
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@ -82,17 +82,12 @@ WAVE_FORMAT_PCM = 0x0001
_array_fmts = None, 'b', 'h', None, 'i'
import audioop
import struct
import sys
from chunk import Chunk
from collections import namedtuple
def _byteswap3(data):
ba = bytearray(data)
ba[::3] = data[2::3]
ba[2::3] = data[::3]
return bytes(ba)
_wave_params = namedtuple('_wave_params',
'nchannels sampwidth framerate nframes comptype compname')
@ -243,29 +238,9 @@ class Wave_read:
self._data_seek_needed = 0
if nframes == 0:
return b''
if self._sampwidth in (2, 4) and sys.byteorder == 'big':
# unfortunately the fromfile() method does not take
# something that only looks like a file object, so
# we have to reach into the innards of the chunk object
import array
chunk = self._data_chunk
data = array.array(_array_fmts[self._sampwidth])
assert data.itemsize == self._sampwidth
nitems = nframes * self._nchannels
if nitems * self._sampwidth > chunk.chunksize - chunk.size_read:
nitems = (chunk.chunksize - chunk.size_read) // self._sampwidth
data.fromfile(chunk.file.file, nitems)
# "tell" data chunk how much was read
chunk.size_read = chunk.size_read + nitems * self._sampwidth
# do the same for the outermost chunk
chunk = chunk.file
chunk.size_read = chunk.size_read + nitems * self._sampwidth
data.byteswap()
data = data.tobytes()
else:
data = self._data_chunk.read(nframes * self._framesize)
if self._sampwidth == 3 and sys.byteorder == 'big':
data = _byteswap3(data)
data = self._data_chunk.read(nframes * self._framesize)
if self._sampwidth != 1 and sys.byteorder == 'big':
data = audioop.byteswap(data, self._sampwidth)
if self._convert and data:
data = self._convert(data)
self._soundpos = self._soundpos + len(data) // (self._nchannels * self._sampwidth)
@ -441,20 +416,10 @@ class Wave_write:
nframes = len(data) // (self._sampwidth * self._nchannels)
if self._convert:
data = self._convert(data)
if self._sampwidth in (2, 4) and sys.byteorder == 'big':
import array
a = array.array(_array_fmts[self._sampwidth])
a.frombytes(data)
data = a
assert data.itemsize == self._sampwidth
data.byteswap()
data.tofile(self._file)
self._datawritten = self._datawritten + len(data) * self._sampwidth
else:
if self._sampwidth == 3 and sys.byteorder == 'big':
data = _byteswap3(data)
self._file.write(data)
self._datawritten = self._datawritten + len(data)
if self._sampwidth != 1 and sys.byteorder == 'big':
data = audioop.byteswap(data, self._sampwidth)
self._file.write(data)
self._datawritten += len(data)
self._nframeswritten = self._nframeswritten + nframes
def writeframes(self, data):