Added support for ADPCM compression.
diff --git a/Lib/aifc.py b/Lib/aifc.py
index c1418be..a9e6f85 100644
--- a/Lib/aifc.py
+++ b/Lib/aifc.py
@@ -514,6 +514,15 @@
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 @@
#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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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: