Added support for ADPCM compression.

diff --git a/Lib/aifc.py b/Lib/aifc.py
index c1418be17738b2fb2acb1d8b0a2bbb93439a764c..a9e6f85006fac2d89921352489f9e1291d93d383 100644 (file)
--- a/Lib/aifc.py
+++ b/Lib/aifc.py
@@ -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: