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Added support for ADPCM compression.

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This commit is contained in:
Sjoerd Mullender 1994-09-06 16:17:51 +00:00
parent 03a909628b
commit 1f05754640
1 changed files with 47 additions and 6 deletions
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53
Lib/aifc.py
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@ -514,6 +514,15 @@ class Aifc_read:
import audioop
return audioop.ulaw2lin(data, 2)
def _adpcm2lin(self, data):
import audioop
if not hasattr(self, '_adpcmstate'):
# first time
self._adpcmstate = None
data, self._adpcmstate = audioop.adpcm2lin(data, 2,
self._adpcmstate)
return data
def _read_comm_chunk(self, chunk):
self._nchannels = _read_short(chunk)
self._nframes = _read_long(chunk)
@ -539,6 +548,16 @@ class Aifc_read:
#DEBUG end
self._compname = _read_string(chunk)
if self._comptype != 'NONE':
if self._comptype == 'G722':
try:
import audioop
except ImportError:
pass
else:
self._convert = self._adpcm2lin
self._framesize = self._framesize / 4
return
# for ULAW and ALAW try Compression Library
try:
import cl, CL
except ImportError:
@ -711,7 +730,7 @@ class Aifc_write:
def setcomptype(self, comptype, compname):
if self._nframeswritten:
raise Error, 'cannot change parameters after starting to write'
if comptype not in ('NONE', 'ULAW', 'ALAW'):
if comptype not in ('NONE', 'ULAW', 'ALAW', 'G722'):
raise Error, 'unsupported compression type'
self._comptype = comptype
self._compname = compname
@ -730,7 +749,7 @@ class Aifc_write:
def setparams(self, (nchannels, sampwidth, framerate, nframes, comptype, compname)):
if self._nframeswritten:
raise Error, 'cannot change parameters after starting to write'
if comptype not in ('NONE', 'ULAW', 'ALAW'):
if comptype not in ('NONE', 'ULAW', 'ALAW', 'G722'):
raise Error, 'unsupported compression type'
self.setnchannels(nchannels)
self.setsampwidth(sampwidth)
@ -817,6 +836,14 @@ class Aifc_write:
import audioop
return audioop.lin2ulaw(data, 2)
def _lin2adpcm(self, data):
import audioop
if not hasattr(self, '_adpcmstate'):
self._adpcmstate = None
data, self._adpcmstate = audioop.lin2adpcm(data, 2,
self._adpcmstate)
return data
def _ensure_header_written(self, datasize):
if not self._nframeswritten:
if self._comptype in ('ULAW', 'ALAW'):
@ -824,6 +851,11 @@ class Aifc_write:
self._sampwidth = 2
if self._sampwidth != 2:
raise Error, 'sample width must be 2 when compressing with ULAW or ALAW'
if self._comptype == 'G722':
if not self._sampwidth:
self._sampwidth = 2
if self._sampwidth != 2:
raise Error, 'sample width must be 2 when compressing with G7.22 (ADPCM)'
if not self._nchannels:
raise Error, '# channels not specified'
if not self._sampwidth:
@ -833,6 +865,10 @@ class Aifc_write:
self._write_header(datasize)
def _init_compression(self):
if self._comptype == 'G722':
import audioop
self._convert = self._lin2adpcm
return
try:
import cl, CL
except ImportError:
@ -876,10 +912,15 @@ class Aifc_write:
self._datalength = self._nframes * self._nchannels * self._sampwidth
if self._datalength & 1:
self._datalength = self._datalength + 1
if self._aifc and self._comptype in ('ULAW', 'ALAW'):
self._datalength = self._datalength / 2
if self._datalength & 1:
self._datalength = self._datalength + 1
if self._aifc:
if self._comptype in ('ULAW', 'ALAW'):
self._datalength = self._datalength / 2
if self._datalength & 1:
self._datalength = self._datalength + 1
elif self._comptype == 'G722':
self._datalength = (self._datalength + 3) / 4
if self._datalength & 1:
self._datalength = self._datalength + 1
self._form_length_pos = self._file.tell()
commlength = self._write_form_length(self._datalength)
if self._aifc: