diff options
Diffstat (limited to 'Lib/wave.py')
| -rw-r--r-- | Lib/wave.py | 559 |
1 files changed, 559 insertions, 0 deletions
diff --git a/Lib/wave.py b/Lib/wave.py new file mode 100644 index 0000000..5d1a1c1 --- /dev/null +++ b/Lib/wave.py @@ -0,0 +1,559 @@ +# Stuff to parse WAVE files. +# +# Usage. +# +# Reading WAVE files: +# f = wave.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' for AIFF files) +# getcompname() -- returns human-readable version of +# compression type ('not compressed' for AIFF files) +# getparams() -- returns a tuple 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 postion in the +# file. +# The close() method is called automatically when the class instance +# is destroyed. +# +# Writing WAVE files: +# f = wave.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(), and +# close(). +# +# 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(nchannels, sampwidth, framerate, nframes, comptype, compname) +# -- 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 file +# You should set the parameters before the first writeframesraw or +# writeframes. 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 to +# be patched up. +# It is best to first set all parameters, perhaps possibly the +# compression type, and then write audio frames using writeframesraw. +# When all frames have been written, either call writeframes('') or +# close() to patch up the sizes in the header. +# The close() method is called automatically when the class instance +# is destroyed. + +import __builtin__ + +Error = 'wave.Error' + +WAVE_FORMAT_PCM = 0x0001 + +_array_fmts = None, 'b', 'h', None, 'l' + +def _read_long(file): + x = 0L + for i in range(4): + byte = file.read(1) + if byte == '': + raise EOFError + x = x + (ord(byte) << (8 * i)) + if x >= 0x80000000L: + x = x - 0x100000000L + return int(x) + +def _read_ulong(file): + x = 0L + for i in range(4): + byte = file.read(1) + if byte == '': + raise EOFError + x = x + (ord(byte) << (8 * i)) + return x + +def _read_short(file): + x = 0 + for i in range(2): + byte = file.read(1) + if byte == '': + raise EOFError + x = x + (ord(byte) << (8 * i)) + if x >= 0x8000: + x = x - 0x10000 + return x + +def _write_short(f, x): + d, m = divmod(x, 256) + f.write(chr(m)) + f.write(chr(d)) + +def _write_long(f, x): + if x < 0: + x = x + 0x100000000L + for i in range(4): + d, m = divmod(x, 256) + f.write(chr(int(m))) + x = d + +class Chunk: + def __init__(self, file): + self.file = file + self.chunkname = self.file.read(4) + if len(self.chunkname) < 4: + raise EOFError + self.chunksize = _read_long(self.file) + self.size_read = 0 + self.offset = self.file.tell() + + def rewind(self): + self.file.seek(self.offset, 0) + self.size_read = 0 + + def setpos(self, pos): + if pos < 0 or pos > self.chunksize: + raise RuntimeError + self.file.seek(self.offset + pos, 0) + self.size_read = pos + + def read(self, length): + if self.size_read >= self.chunksize: + return '' + if length > self.chunksize - self.size_read: + length = self.chunksize - self.size_read + data = self.file.read(length) + self.size_read = self.size_read + len(data) + return data + + def skip(self): + try: + self.file.seek(self.chunksize - self.size_read, 1) + except RuntimeError: + while self.size_read < self.chunksize: + dummy = self.read(8192) + if not dummy: + raise EOFError + +class Wave_read: + # Variables used in this class: + # + # These variables are available to the user though appropriate + # methods of this class: + # _file -- the open file with methods read(), close(), and seek() + # set through the __init__() method + # _nchannels -- the number of audio channels + # available through the getnchannels() method + # _nframes -- the number of audio frames + # available through the getnframes() method + # _sampwidth -- the number of bytes per audio sample + # available through the getsampwidth() method + # _framerate -- the sampling frequency + # available through the getframerate() method + # _comptype -- the AIFF-C compression type ('NONE' if AIFF) + # available through the getcomptype() method + # _compname -- the human-readable AIFF-C compression type + # available through the getcomptype() method + # _soundpos -- the position in the audio stream + # available through the tell() method, set through the + # setpos() method + # + # These variables are used internally only: + # _fmt_chunk_read -- 1 iff the FMT chunk has been read + # _data_seek_needed -- 1 iff positioned correctly in audio + # file for readframes() + # _data_chunk -- instantiation of a chunk class for the DATA chunk + # _framesize -- size of one frame in the file + + access _file, _nchannels, _nframes, _sampwidth, _framerate, \ + _comptype, _compname, _soundpos, \ + _fmt_chunk_read, _data_seek_needed, \ + _data_chunk, _framesize: private + + def initfp(self, file): + self._file = file + self._convert = None + self._soundpos = 0 + form = self._file.read(4) + if form != 'RIFF': + raise Error, 'file does not start with RIFF id' + formlength = _read_long(self._file) + if formlength <= 0: + raise Error, 'invalid FORM chunk data size' + formdata = self._file.read(4) + formlength = formlength - 4 + if formdata != 'WAVE': + raise Error, 'not a WAVE file' + self._fmt_chunk_read = 0 + while formlength > 0: + self._data_seek_needed = 1 + chunk = Chunk(self._file) + if chunk.chunkname == 'fmt ': + self._read_fmt_chunk(chunk) + self._fmt_chunk_read = 1 + elif chunk.chunkname == 'data': + if not self._fmt_chunk_read: + raise Error, 'data chunk before fmt chunk' + self._data_chunk = chunk + self._nframes = chunk.chunksize / self._framesize + self._data_seek_needed = 0 + formlength = formlength - 8 - chunk.chunksize + if formlength > 0: + chunk.skip() + if not self._fmt_chunk_read or not self._data_chunk: + raise Error, 'fmt chunk and/or data chunk missing' + + def __init__(self, f): + if type(f) == type(''): + f = __builtin__.open(f, 'r') + # else, assume it is an open file object already + self.initfp(f) + + def __del__(self): + if self._file: + self.close() + + # + # User visible methods. + # + def getfp(self): + return self._file + + def rewind(self): + self._data_seek_needed = 1 + self._soundpos = 0 + + def close(self): + self._file = None + + def tell(self): + return self._soundpos + + def getnchannels(self): + return self._nchannels + + def getnframes(self): + return self._nframes + + def getsampwidth(self): + return self._sampwidth + + def getframerate(self): + return self._framerate + + def getcomptype(self): + return self._comptype + + def getcompname(self): + return self._compname + + def getparams(self): + return 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 setpos(self, pos): + if pos < 0 or pos > self._nframes: + raise Error, 'position not in range' + self._soundpos = pos + self._data_seek_needed = 1 + + def readframes(self, nframes): + if self._data_seek_needed: + self._data_chunk.rewind() + pos = self._soundpos * self._framesize + if pos: + self._data_chunk.setpos(pos) + self._data_seek_needed = 0 + if nframes == 0: + return '' + if self._sampwidth > 1: + # 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 + data = array.array(_array_fmts[self._sampwidth]) + nitems = nframes * self._nchannels + if nitems * self._sampwidth > self._data_chunk.chunksize - self._data_chunk.size_read: + nitems = (self._data_chunk.chunksize - self._data_chunk.size_read) / self._sampwidth + data.fromfile(self._data_chunk.file, nitems) + self._data_chunk.size_read = self._data_chunk.size_read + nitems * self._sampwidth + data.byteswap() + data = data.tostring() + else: + data = self._data_chunk.read(nframes * self._framesize) + if self._convert and data: + data = self._convert(data) + self._soundpos = self._soundpos + len(data) / (self._nchannels * self._sampwidth) + return data + + # + # Internal methods. + # + access *: private + + def _read_fmt_chunk(self, chunk): + wFormatTag = _read_short(chunk) + self._nchannels = _read_short(chunk) + self._framerate = _read_long(chunk) + dwAvgBytesPerSec = _read_long(chunk) + wBlockAlign = _read_short(chunk) + if wFormatTag == WAVE_FORMAT_PCM: + self._sampwidth = (_read_short(chunk) + 7) / 8 + else: + raise Error, 'unknown format' + self._framesize = self._nchannels * self._sampwidth + self._comptype = 'NONE' + self._compname = 'not compressed' + +class Wave_write: + # Variables used in this class: + # + # These variables are user settable through appropriate methods + # of this class: + # _file -- the open file with methods write(), close(), tell(), seek() + # set through the __init__() method + # _comptype -- the AIFF-C compression type ('NONE' in AIFF) + # set through the setcomptype() or setparams() method + # _compname -- the human-readable AIFF-C compression type + # set through the setcomptype() or setparams() method + # _nchannels -- the number of audio channels + # set through the setnchannels() or setparams() method + # _sampwidth -- the number of bytes per audio sample + # set through the setsampwidth() or setparams() method + # _framerate -- the sampling frequency + # set through the setframerate() or setparams() method + # _nframes -- the number of audio frames written to the header + # set through the setnframes() or setparams() method + # + # These variables are used internally only: + # _datalength -- the size of the audio samples written to the header + # _nframeswritten -- the number of frames actually written + # _datawritten -- the size of the audio samples actually written + + access _file, _comptype, _compname, _nchannels, _sampwidth, \ + _framerate, _nframes, _nframeswritten, \ + _datalength, _datawritten: private + + def __init__(self, f): + if type(f) == type(''): + f = __builtin__.open(f, 'w') + self.initfp(f) + + def initfp(self, file): + self._file = file + self._convert = None + self._nchannels = 0 + self._sampwidth = 0 + self._framerate = 0 + self._nframes = 0 + self._nframeswritten = 0 + self._datawritten = 0 + self._datalength = 0 + + def __del__(self): + if self._file: + self.close() + + # + # User visible methods. + # + def setnchannels(self, nchannels): + if self._datawritten: + raise Error, 'cannot change parameters after starting to write' + if nchannels < 1: + raise Error, 'bad # of channels' + 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._datawritten: + raise Error, 'cannot change parameters after starting to write' + if sampwidth < 1 or sampwidth > 4: + raise Error, 'bad sample width' + self._sampwidth = sampwidth + + def getsampwidth(self): + if not self._sampwidth: + raise Error, 'sample width not set' + return self._sampwidth + + def setframerate(self, framerate): + if self._datawritten: + raise Error, 'cannot change parameters after starting to write' + if framerate <= 0: + raise Error, 'bad frame rate' + 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._datawritten: + raise Error, 'cannot change parameters after starting to write' + self._nframes = nframes + + def getnframes(self): + return self._nframeswritten + + def setcomptype(self, comptype, compname): + if self._datawritten: + raise Error, 'cannot change parameters after starting to write' + if comptype not in ('NONE',): + raise Error, 'unsupported compression type' + self._comptype = comptype + self._compname = compname + + def getcomptype(self): + return self._comptype + + def getcompname(self): + return self._compname + + def setparams(self, (nchannels, sampwidth, framerate, nframes, comptype, compname)): + if self._datawritten: + raise Error, 'cannot change parameters after starting to write' + self.setnchannels(nchannels) + self.setsampwidth(sampwidth) + self.setframerate(framerate) + self.setnframes(nframes) + self.setcomptype(comptype, compname) + + def getparams(self): + if not self._nchannels or not self._sampwidth or not self._framerate: + raise Error, 'not all parameters set' + return self._nchannels, self._sampwidth, self._framerate, \ + self._nframes, self._comptype, self._compname + + def setmark(self, id, pos, name): + raise Error, 'setmark() not supported' + + def getmark(self, id): + raise Error, 'no marks' + + def getmarkers(self): + return None + + def tell(self): + return self._nframeswritten + + def writeframesraw(self, data): + self._ensure_header_written(len(data)) + nframes = len(data) / (self._sampwidth * self._nchannels) + if self._convert: + data = self._convert(data) + if self._sampwidth > 1: + import array + data = array.array(_array_fmts[self._sampwidth], data) + data.byteswap() + data.tofile(self._file) + self._datawritten = self._datawritten + len(data) * self._sampwidth + else: + self._file.write(data) + self._datawritten = self._datawritten + len(data) + self._nframeswritten = self._nframeswritten + nframes + + def writeframes(self, data): + self.writeframesraw(data) + if self._datalength != self._datawritten: + self._patchheader() + + def close(self): + self._ensure_header_written(0) + if self._datalength != self._datawritten: + self._patchheader() + self._file.flush() + self._file = None + + # + # Internal methods. + # + access *: private + + def _ensure_header_written(self, datasize): + if not self._datawritten: + if not self._nchannels: + raise Error, '# channels not specified' + if not self._sampwidth: + raise Error, 'sample width not specified' + if not self._framerate: + raise Error, 'sampling rate not specified' + self._write_header(datasize) + + def _write_header(self, initlength): + self._file.write('RIFF') + if not self._nframes: + self._nframes = initlength / (self._nchannels * self._sampwidth) + self._datalength = self._nframes * self._nchannels * self._sampwidth + self._form_length_pos = self._file.tell() + _write_long(self._file, 36 + self._datalength) + self._file.write('WAVE') + self._file.write('fmt ') + _write_long(self._file, 16) + _write_short(self._file, WAVE_FORMAT_PCM) + _write_short(self._file, self._nchannels) + _write_long(self._file, self._framerate) + _write_long(self._file, self._nchannels * self._framerate * self._sampwidth) + _write_short(self._file, self._nchannels * self._sampwidth) + _write_short(self._file, self._sampwidth * 8) + self._file.write('data') + self._data_length_pos = self._file.tell() + _write_long(self._file, self._datalength) + + def _patchheader(self): + if self._datawritten == self._datalength: + return + curpos = self._file.tell() + self._file.seek(self._form_length_pos, 0) + _write_long(36 + self._datawritten) + self._file.seek(self._data_length_pos, 0) + _write_long(self._file, self._datawritten) + self._file.seek(curpos, 0) + self._datalength = self._datawritten + +def open(f, mode): + if mode == 'r': + return Wave_read(f) + elif mode == 'w': + return Wave_write(f) + else: + raise Error, "mode must be 'r' or 'w'" + +openfp = open # B/W compatibility |