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Diffstat (limited to 'lib/python2.7/wave.py')
| -rw-r--r-- | lib/python2.7/wave.py | 517 |
1 files changed, 517 insertions, 0 deletions
diff --git a/lib/python2.7/wave.py b/lib/python2.7/wave.py new file mode 100644 index 0000000..28acaa6 --- /dev/null +++ b/lib/python2.7/wave.py @@ -0,0 +1,517 @@ +"""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 linear samples) + getcompname() -- returns human-readable version of + compression type ('not compressed' linear samples) + 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 position 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(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 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__ + +__all__ = ["open", "openfp", "Error"] + +class Error(Exception): + pass + +WAVE_FORMAT_PCM = 0x0001 + +_array_fmts = None, 'b', 'h', None, 'i' + +import struct +import sys +from chunk import Chunk + +def _byteswap3(data): + ba = bytearray(data) + ba[::3] = data[2::3] + ba[2::3] = data[::3] + return bytes(ba) + +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 + """ + + def initfp(self, file): + self._convert = None + self._soundpos = 0 + self._file = Chunk(file, bigendian = 0) + if self._file.getname() != 'RIFF': + raise Error, 'file does not start with RIFF id' + if self._file.read(4) != 'WAVE': + raise Error, 'not a WAVE file' + self._fmt_chunk_read = 0 + self._data_chunk = None + while 1: + self._data_seek_needed = 1 + try: + chunk = Chunk(self._file, bigendian = 0) + except EOFError: + break + chunkname = chunk.getname() + if chunkname == 'fmt ': + self._read_fmt_chunk(chunk) + self._fmt_chunk_read = 1 + elif 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 + break + 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): + self._i_opened_the_file = None + if isinstance(f, basestring): + f = __builtin__.open(f, 'rb') + self._i_opened_the_file = f + # else, assume it is an open file object already + try: + self.initfp(f) + except: + if self._i_opened_the_file: + f.close() + raise + + def __del__(self): + 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 + file = self._i_opened_the_file + if file: + self._i_opened_the_file = None + file.close() + + 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.seek(0, 0) + pos = self._soundpos * self._framesize + if pos: + self._data_chunk.seek(pos, 0) + self._data_seek_needed = 0 + if nframes == 0: + return '' + if self._sampwidth in (2, 4) and sys.byteorder == 'big': + # 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 + chunk = self._data_chunk + data = array.array(_array_fmts[self._sampwidth]) + assert data.itemsize == self._sampwidth + nitems = nframes * self._nchannels + if nitems * self._sampwidth > chunk.chunksize - chunk.size_read: + nitems = (chunk.chunksize - chunk.size_read) // self._sampwidth + data.fromfile(chunk.file.file, nitems) + # "tell" data chunk how much was read + chunk.size_read = chunk.size_read + nitems * self._sampwidth + # do the same for the outermost chunk + chunk = chunk.file + chunk.size_read = chunk.size_read + nitems * self._sampwidth + data.byteswap() + data = data.tostring() + else: + data = self._data_chunk.read(nframes * self._framesize) + if self._sampwidth == 3 and sys.byteorder == 'big': + data = _byteswap3(data) + if self._convert and data: + data = self._convert(data) + self._soundpos = self._soundpos + len(data) // (self._nchannels * self._sampwidth) + return data + + # + # Internal methods. + # + + def _read_fmt_chunk(self, chunk): + wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack('<HHLLH', chunk.read(14)) + if wFormatTag == WAVE_FORMAT_PCM: + sampwidth = struct.unpack('<H', chunk.read(2))[0] + self._sampwidth = (sampwidth + 7) // 8 + else: + raise Error, 'unknown format: %r' % (wFormatTag,) + 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 + """ + + def __init__(self, f): + self._i_opened_the_file = None + if isinstance(f, basestring): + f = __builtin__.open(f, 'wb') + self._i_opened_the_file = f + try: + self.initfp(f) + except: + if self._i_opened_the_file: + f.close() + raise + + 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 + self._headerwritten = False + + def __del__(self): + 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, params): + nchannels, sampwidth, framerate, nframes, comptype, compname = params + 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 in (2, 4) and sys.byteorder == 'big': + import array + a = array.array(_array_fmts[self._sampwidth]) + a.fromstring(data) + data = a + assert data.itemsize == self._sampwidth + data.byteswap() + data.tofile(self._file) + self._datawritten = self._datawritten + len(data) * self._sampwidth + else: + if self._sampwidth == 3 and sys.byteorder == 'big': + data = _byteswap3(data) + 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): + try: + if self._file: + self._ensure_header_written(0) + if self._datalength != self._datawritten: + self._patchheader() + self._file.flush() + finally: + self._file = None + file = self._i_opened_the_file + if file: + self._i_opened_the_file = None + file.close() + + # + # Internal methods. + # + + def _ensure_header_written(self, datasize): + if not self._headerwritten: + 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): + assert not self._headerwritten + 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() + self._file.write(struct.pack('<L4s4sLHHLLHH4s', + 36 + self._datalength, 'WAVE', 'fmt ', 16, + WAVE_FORMAT_PCM, self._nchannels, self._framerate, + self._nchannels * self._framerate * self._sampwidth, + self._nchannels * self._sampwidth, + self._sampwidth * 8, 'data')) + self._data_length_pos = self._file.tell() + self._file.write(struct.pack('<L', self._datalength)) + self._headerwritten = True + + def _patchheader(self): + assert self._headerwritten + if self._datawritten == self._datalength: + return + curpos = self._file.tell() + self._file.seek(self._form_length_pos, 0) + self._file.write(struct.pack('<L', 36 + self._datawritten)) + self._file.seek(self._data_length_pos, 0) + self._file.write(struct.pack('<L', self._datawritten)) + self._file.seek(curpos, 0) + self._datalength = self._datawritten + +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 Wave_read(f) + elif mode in ('w', 'wb'): + return Wave_write(f) + else: + raise Error, "mode must be 'r', 'rb', 'w', or 'wb'" + +openfp = open # B/W compatibility |