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sunau.py17.7 KB · 527 lines
"""Stuff to parse Sun and NeXT audio files. An audio file consists of a header followed by the data.  The structureof the header is as follows.         +---------------+        | magic word    |        +---------------+        | header size   |        +---------------+        | data size     |        +---------------+        | encoding      |        +---------------+        | sample rate   |        +---------------+        | # of channels |        +---------------+        | info          |        |               |        +---------------+ The magic word consists of the 4 characters '.snd'.  Apart from theinfo field, all header fields are 4 bytes in size.  They are all32-bit unsigned integers encoded in big-endian byte order. The header size really gives the start of the data.The data size is the physical size of the data.  From the otherparameters the number of frames can be calculated.The encoding gives the way in which audio samples are encoded.Possible values are listed below.The info field currently consists of an ASCII string giving ahuman-readable description of the audio file.  The info field ispadded with NUL bytes to the header size. Usage. Reading audio files:        f = sunau.open(file, 'r')where file is either the name of a file or an open file pointer.The open file pointer must have methods read(), seek(), and close().When the setpos() and rewind() methods are not used, the seek()method is not  necessary. This returns an instance of a class with the following public methods:        getnchannels()  -- returns number of audio channels (1 for                           mono, 2 for stereo)        getsampwidth()  -- returns sample width in bytes        getframerate()  -- returns sampling frequency        getnframes()    -- returns number of audio frames        getcomptype()   -- returns compression type ('NONE' or 'ULAW')        getcompname()   -- returns human-readable version of                           compression type ('not compressed' matches 'NONE')        getparams()     -- returns a namedtuple consisting of all of the                           above in the above order        getmarkers()    -- returns None (for compatibility with the                           aifc module)        getmark(id)     -- raises an error since the mark does not                           exist (for compatibility with the aifc module)        readframes(n)   -- returns at most n frames of audio        rewind()        -- rewind to the beginning of the audio stream        setpos(pos)     -- seek to the specified position        tell()          -- return the current position        close()         -- close the instance (make it unusable)The position returned by tell() and the position given to setpos()are compatible and have nothing to do with the actual position in thefile.The close() method is called automatically when the class instanceis destroyed. Writing audio files:        f = sunau.open(file, 'w')where file is either the name of a file or an open file pointer.The open file pointer must have methods write(), tell(), seek(), andclose(). This returns an instance of a class with the following public methods:        setnchannels(n) -- set the number of channels        setsampwidth(n) -- set the sample width        setframerate(n) -- set the frame rate        setnframes(n)   -- set the number of frames        setcomptype(type, name)                        -- set the compression type and the                           human-readable compression type        setparams(tuple)-- set all parameters at once        tell()          -- return current position in output file        writeframesraw(data)                        -- write audio frames without pathing up the                           file header        writeframes(data)                        -- write audio frames and patch up the file header        close()         -- patch up the file header and close the                           output fileYou should set the parameters before the first writeframesraw orwriteframes.  The total number of frames does not need to be set,but when it is set to the correct value, the header does not have tobe patched up.It is best to first set all parameters, perhaps possibly thecompression type, and then write audio frames using writeframesraw.When all frames have been written, either call writeframes(b'') orclose() to patch up the sizes in the header.The close() method is called automatically when the class instanceis destroyed.""" from collections import namedtuple  _sunau_params = namedtuple('_sunau_params',                           'nchannels sampwidth framerate nframes comptype compname') # from <multimedia/audio_filehdr.h>AUDIO_FILE_MAGIC = 0x2e736e64AUDIO_FILE_ENCODING_MULAW_8 = 1AUDIO_FILE_ENCODING_LINEAR_8 = 2AUDIO_FILE_ENCODING_LINEAR_16 = 3AUDIO_FILE_ENCODING_LINEAR_24 = 4AUDIO_FILE_ENCODING_LINEAR_32 = 5AUDIO_FILE_ENCODING_FLOAT = 6AUDIO_FILE_ENCODING_DOUBLE = 7AUDIO_FILE_ENCODING_ADPCM_G721 = 23AUDIO_FILE_ENCODING_ADPCM_G722 = 24AUDIO_FILE_ENCODING_ADPCM_G723_3 = 25AUDIO_FILE_ENCODING_ADPCM_G723_5 = 26AUDIO_FILE_ENCODING_ALAW_8 = 27 # from <multimedia/audio_hdr.h>AUDIO_UNKNOWN_SIZE = 0xFFFFFFFF        # ((unsigned)(~0)) _simple_encodings = [AUDIO_FILE_ENCODING_MULAW_8,                     AUDIO_FILE_ENCODING_LINEAR_8,                     AUDIO_FILE_ENCODING_LINEAR_16,                     AUDIO_FILE_ENCODING_LINEAR_24,                     AUDIO_FILE_ENCODING_LINEAR_32,                     AUDIO_FILE_ENCODING_ALAW_8] class Error(Exception):    pass def _read_u32(file):    x = 0    for i in range(4):        byte = file.read(1)        if not byte:            raise EOFError        x = x*256 + ord(byte)    return x def _write_u32(file, x):    data = []    for i in range(4):        d, m = divmod(x, 256)        data.insert(0, int(m))        x = d    file.write(bytes(data)) class Au_read:     def __init__(self, f):        if type(f) == type(''):            import builtins            f = builtins.open(f, 'rb')            self._opened = True        else:            self._opened = False        self.initfp(f)     def __del__(self):        if self._file:            self.close()     def __enter__(self):        return self     def __exit__(self, *args):        self.close()     def initfp(self, file):        self._file = file        self._soundpos = 0        magic = int(_read_u32(file))        if magic != AUDIO_FILE_MAGIC:            raise Error('bad magic number')        self._hdr_size = int(_read_u32(file))        if self._hdr_size < 24:            raise Error('header size too small')        if self._hdr_size > 100:            raise Error('header size ridiculously large')        self._data_size = _read_u32(file)        if self._data_size != AUDIO_UNKNOWN_SIZE:            self._data_size = int(self._data_size)        self._encoding = int(_read_u32(file))        if self._encoding not in _simple_encodings:            raise Error('encoding not (yet) supported')        if self._encoding in (AUDIO_FILE_ENCODING_MULAW_8,                  AUDIO_FILE_ENCODING_ALAW_8):            self._sampwidth = 2            self._framesize = 1        elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_8:            self._framesize = self._sampwidth = 1        elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_16:            self._framesize = self._sampwidth = 2        elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_24:            self._framesize = self._sampwidth = 3        elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_32:            self._framesize = self._sampwidth = 4        else:            raise Error('unknown encoding')        self._framerate = int(_read_u32(file))        self._nchannels = int(_read_u32(file))        if not self._nchannels:            raise Error('bad # of channels')        self._framesize = self._framesize * self._nchannels        if self._hdr_size > 24:            self._info = file.read(self._hdr_size - 24)            self._info, _, _ = self._info.partition(b'\0')        else:            self._info = b''        try:            self._data_pos = file.tell()        except (AttributeError, OSError):            self._data_pos = None     def getfp(self):        return self._file     def getnchannels(self):        return self._nchannels     def getsampwidth(self):        return self._sampwidth     def getframerate(self):        return self._framerate     def getnframes(self):        if self._data_size == AUDIO_UNKNOWN_SIZE:            return AUDIO_UNKNOWN_SIZE        if self._encoding in _simple_encodings:            return self._data_size // self._framesize        return 0                # XXX--must do some arithmetic here     def getcomptype(self):        if self._encoding == AUDIO_FILE_ENCODING_MULAW_8:            return 'ULAW'        elif self._encoding == AUDIO_FILE_ENCODING_ALAW_8:            return 'ALAW'        else:            return 'NONE'     def getcompname(self):        if self._encoding == AUDIO_FILE_ENCODING_MULAW_8:            return 'CCITT G.711 u-law'        elif self._encoding == AUDIO_FILE_ENCODING_ALAW_8:            return 'CCITT G.711 A-law'        else:            return 'not compressed'     def getparams(self):        return _sunau_params(self.getnchannels(), self.getsampwidth(),                  self.getframerate(), self.getnframes(),                  self.getcomptype(), self.getcompname())     def getmarkers(self):        return None     def getmark(self, id):        raise Error('no marks')     def readframes(self, nframes):        if self._encoding in _simple_encodings:            if nframes == AUDIO_UNKNOWN_SIZE:                data = self._file.read()            else:                data = self._file.read(nframes * self._framesize)            self._soundpos += len(data) // self._framesize            if self._encoding == AUDIO_FILE_ENCODING_MULAW_8:                import audioop                data = audioop.ulaw2lin(data, self._sampwidth)            return data        return None             # XXX--not implemented yet     def rewind(self):        if self._data_pos is None:            raise OSError('cannot seek')        self._file.seek(self._data_pos)        self._soundpos = 0     def tell(self):        return self._soundpos     def setpos(self, pos):        if pos < 0 or pos > self.getnframes():            raise Error('position not in range')        if self._data_pos is None:            raise OSError('cannot seek')        self._file.seek(self._data_pos + pos * self._framesize)        self._soundpos = pos     def close(self):        file = self._file        if file:            self._file = None            if self._opened:                file.close() class Au_write:     def __init__(self, f):        if type(f) == type(''):            import builtins            f = builtins.open(f, 'wb')            self._opened = True        else:            self._opened = False        self.initfp(f)     def __del__(self):        if self._file:            self.close()        self._file = None     def __enter__(self):        return self     def __exit__(self, *args):        self.close()     def initfp(self, file):        self._file = file        self._framerate = 0        self._nchannels = 0        self._sampwidth = 0        self._framesize = 0        self._nframes = AUDIO_UNKNOWN_SIZE        self._nframeswritten = 0        self._datawritten = 0        self._datalength = 0        self._info = b''        self._comptype = 'ULAW' # default is U-law     def setnchannels(self, nchannels):        if self._nframeswritten:            raise Error('cannot change parameters after starting to write')        if nchannels not in (1, 2, 4):            raise Error('only 1, 2, or 4 channels supported')        self._nchannels = nchannels     def getnchannels(self):        if not self._nchannels:            raise Error('number of channels not set')        return self._nchannels     def setsampwidth(self, sampwidth):        if self._nframeswritten:            raise Error('cannot change parameters after starting to write')        if sampwidth not in (1, 2, 3, 4):            raise Error('bad sample width')        self._sampwidth = sampwidth     def getsampwidth(self):        if not self._framerate:            raise Error('sample width not specified')        return self._sampwidth     def setframerate(self, framerate):        if self._nframeswritten:            raise Error('cannot change parameters after starting to write')        self._framerate = framerate     def getframerate(self):        if not self._framerate:            raise Error('frame rate not set')        return self._framerate     def setnframes(self, nframes):        if self._nframeswritten:            raise Error('cannot change parameters after starting to write')        if nframes < 0:            raise Error('# of frames cannot be negative')        self._nframes = nframes     def getnframes(self):        return self._nframeswritten     def setcomptype(self, type, name):        if type in ('NONE', 'ULAW'):            self._comptype = type        else:            raise Error('unknown compression type')     def getcomptype(self):        return self._comptype     def getcompname(self):        if self._comptype == 'ULAW':            return 'CCITT G.711 u-law'        elif self._comptype == 'ALAW':            return 'CCITT G.711 A-law'        else:            return 'not compressed'     def setparams(self, params):        nchannels, sampwidth, framerate, nframes, comptype, compname = params        self.setnchannels(nchannels)        self.setsampwidth(sampwidth)        self.setframerate(framerate)        self.setnframes(nframes)        self.setcomptype(comptype, compname)     def getparams(self):        return _sunau_params(self.getnchannels(), self.getsampwidth(),                  self.getframerate(), self.getnframes(),                  self.getcomptype(), self.getcompname())     def tell(self):        return self._nframeswritten     def writeframesraw(self, data):        if not isinstance(data, (bytes, bytearray)):            data = memoryview(data).cast('B')        self._ensure_header_written()        if self._comptype == 'ULAW':            import audioop            data = audioop.lin2ulaw(data, self._sampwidth)        nframes = len(data) // self._framesize        self._file.write(data)        self._nframeswritten = self._nframeswritten + nframes        self._datawritten = self._datawritten + len(data)     def writeframes(self, data):        self.writeframesraw(data)        if self._nframeswritten != self._nframes or \                  self._datalength != self._datawritten:            self._patchheader()     def close(self):        if self._file:            try:                self._ensure_header_written()                if self._nframeswritten != self._nframes or \                        self._datalength != self._datawritten:                    self._patchheader()                self._file.flush()            finally:                file = self._file                self._file = None                if self._opened:                    file.close()     #    # private methods    #     def _ensure_header_written(self):        if not self._nframeswritten:            if not self._nchannels:                raise Error('# of channels not specified')            if not self._sampwidth:                raise Error('sample width not specified')            if not self._framerate:                raise Error('frame rate not specified')            self._write_header()     def _write_header(self):        if self._comptype == 'NONE':            if self._sampwidth == 1:                encoding = AUDIO_FILE_ENCODING_LINEAR_8                self._framesize = 1            elif self._sampwidth == 2:                encoding = AUDIO_FILE_ENCODING_LINEAR_16                self._framesize = 2            elif self._sampwidth == 3:                encoding = AUDIO_FILE_ENCODING_LINEAR_24                self._framesize = 3            elif self._sampwidth == 4:                encoding = AUDIO_FILE_ENCODING_LINEAR_32                self._framesize = 4            else:                raise Error('internal error')        elif self._comptype == 'ULAW':            encoding = AUDIO_FILE_ENCODING_MULAW_8            self._framesize = 1        else:            raise Error('internal error')        self._framesize = self._framesize * self._nchannels        _write_u32(self._file, AUDIO_FILE_MAGIC)        header_size = 25 + len(self._info)        header_size = (header_size + 7) & ~7        _write_u32(self._file, header_size)        if self._nframes == AUDIO_UNKNOWN_SIZE:            length = AUDIO_UNKNOWN_SIZE        else:            length = self._nframes * self._framesize        try:            self._form_length_pos = self._file.tell()        except (AttributeError, OSError):            self._form_length_pos = None        _write_u32(self._file, length)        self._datalength = length        _write_u32(self._file, encoding)        _write_u32(self._file, self._framerate)        _write_u32(self._file, self._nchannels)        self._file.write(self._info)        self._file.write(b'\0'*(header_size - len(self._info) - 24))     def _patchheader(self):        if self._form_length_pos is None:            raise OSError('cannot seek')        self._file.seek(self._form_length_pos)        _write_u32(self._file, self._datawritten)        self._datalength = self._datawritten        self._file.seek(0, 2) def open(f, mode=None):    if mode is None:        if hasattr(f, 'mode'):            mode = f.mode        else:            mode = 'rb'    if mode in ('r', 'rb'):        return Au_read(f)    elif mode in ('w', 'wb'):        return Au_write(f)    else:        raise Error("mode must be 'r', 'rb', 'w', or 'wb'")