1 """Stuff to parse WAVE files.

     2 

     3 Usage.

     4 

     5 Reading WAVE files:

     6       f = wave.open(file, 'r')

     7 where file is either the name of a file or an open file pointer.

     8 The open file pointer must have methods read(), seek(), and close().

     9 When the setpos() and rewind() methods are not used, the seek()

    10 method is not  necessary.

    11 

    12 This returns an instance of a class with the following public methods:

    13       getnchannels()  -- returns number of audio channels (1 for

    14                          mono, 2 for stereo)

    15       getsampwidth()  -- returns sample width in bytes

    16       getframerate()  -- returns sampling frequency

    17       getnframes()    -- returns number of audio frames

    18       getcomptype()   -- returns compression type ('NONE' for linear samples)

    19       getcompname()   -- returns human-readable version of

    20                          compression type ('not compressed' linear samples)

    21       getparams()     -- returns a tuple consisting of all of the

    22                          above in the above order

    23       getmarkers()    -- returns None (for compatibility with the

    24                          aifc module)

    25       getmark(id)     -- raises an error since the mark does not

    26                          exist (for compatibility with the aifc module)

    27       readframes(n)   -- returns at most n frames of audio

    28       rewind()        -- rewind to the beginning of the audio stream

    29       setpos(pos)     -- seek to the specified position

    30       tell()          -- return the current position

    31       close()         -- close the instance (make it unusable)

    32 The position returned by tell() and the position given to setpos()

    33 are compatible and have nothing to do with the actual position in the

    34 file.

    35 The close() method is called automatically when the class instance

    36 is destroyed.

    37 

    38 Writing WAVE files:

    39       f = wave.open(file, 'w')

    40 where file is either the name of a file or an open file pointer.

    41 The open file pointer must have methods write(), tell(), seek(), and

    42 close().

    43 

    44 This returns an instance of a class with the following public methods:

    45       setnchannels(n) -- set the number of channels

    46       setsampwidth(n) -- set the sample width

    47       setframerate(n) -- set the frame rate

    48       setnframes(n)   -- set the number of frames

    49       setcomptype(type, name)

    50                       -- set the compression type and the

    51                          human-readable compression type

    52       setparams(tuple)

    53                       -- set all parameters at once

    54       tell()          -- return current position in output file

    55       writeframesraw(data)

    56                       -- write audio frames without pathing up the

    57                          file header

    58       writeframes(data)

    59                       -- write audio frames and patch up the file header

    60       close()         -- patch up the file header and close the

    61                          output file

    62 You should set the parameters before the first writeframesraw or

    63 writeframes.  The total number of frames does not need to be set,

    64 but when it is set to the correct value, the header does not have to

    65 be patched up.

    66 It is best to first set all parameters, perhaps possibly the

    67 compression type, and then write audio frames using writeframesraw.

    68 When all frames have been written, either call writeframes('') or

    69 close() to patch up the sizes in the header.

    70 The close() method is called automatically when the class instance

    71 is destroyed.

    72 """

    73 

    74 import __builtin__

    75 

    76 __all__ = ["open", "openfp", "Error"]

    77 

    78 class Error(Exception):

    79     pass

    80 

    81 WAVE_FORMAT_PCM = 0x0001

    82 

    83 _array_fmts = None, 'b', 'h', None, 'l'

    84 

    85 # Determine endian-ness

    86 import struct

    87 if struct.pack("h", 1) == "\000\001":

    88     big_endian = 1

    89 else:

    90     big_endian = 0

    91 

    92 from chunk import Chunk

    93 

    94 class Wave_read:

    95     """Variables used in this class:

    96 

    97     These variables are available to the user though appropriate

    98     methods of this class:

    99     _file -- the open file with methods read(), close(), and seek()

   100               set through the __init__() method

   101     _nchannels -- the number of audio channels

   102               available through the getnchannels() method

   103     _nframes -- the number of audio frames

   104               available through the getnframes() method

   105     _sampwidth -- the number of bytes per audio sample

   106               available through the getsampwidth() method

   107     _framerate -- the sampling frequency

   108               available through the getframerate() method

   109     _comptype -- the AIFF-C compression type ('NONE' if AIFF)

   110               available through the getcomptype() method

   111     _compname -- the human-readable AIFF-C compression type

   112               available through the getcomptype() method

   113     _soundpos -- the position in the audio stream

   114               available through the tell() method, set through the

   115               setpos() method

   116 

   117     These variables are used internally only:

   118     _fmt_chunk_read -- 1 iff the FMT chunk has been read

   119     _data_seek_needed -- 1 iff positioned correctly in audio

   120               file for readframes()

   121     _data_chunk -- instantiation of a chunk class for the DATA chunk

   122     _framesize -- size of one frame in the file

   123     """

   124 

   125     def initfp(self, file):

   126         self._convert = None

   127         self._soundpos = 0

   128         self._file = Chunk(file, bigendian = 0)

   129         if self._file.getname() != 'RIFF':

   130             raise Error, 'file does not start with RIFF id'

   131         if self._file.read(4) != 'WAVE':

   132             raise Error, 'not a WAVE file'

   133         self._fmt_chunk_read = 0

   134         self._data_chunk = None

   135         while 1:

   136             self._data_seek_needed = 1

   137             try:

   138                 chunk = Chunk(self._file, bigendian = 0)

   139             except EOFError:

   140                 break

   141             chunkname = chunk.getname()

   142             if chunkname == 'fmt ':

   143                 self._read_fmt_chunk(chunk)

   144                 self._fmt_chunk_read = 1

   145             elif chunkname == 'data':

   146                 if not self._fmt_chunk_read:

   147                     raise Error, 'data chunk before fmt chunk'

   148                 self._data_chunk = chunk

   149                 self._nframes = chunk.chunksize // self._framesize

   150                 self._data_seek_needed = 0

   151                 break

   152             chunk.skip()

   153         if not self._fmt_chunk_read or not self._data_chunk:

   154             raise Error, 'fmt chunk and/or data chunk missing'

   155 

   156     def __init__(self, f):

   157         self._i_opened_the_file = None

   158         if isinstance(f, basestring):

   159             f = __builtin__.open(f, 'rb')

   160             self._i_opened_the_file = f

   161         # else, assume it is an open file object already

   162         try:

   163             self.initfp(f)

   164         except:

   165             if self._i_opened_the_file:

   166                 f.close()

   167             raise

   168 

   169     def __del__(self):

   170         self.close()

   171     #

   172     # User visible methods.

   173     #

   174     def getfp(self):

   175         return self._file

   176 

   177     def rewind(self):

   178         self._data_seek_needed = 1

   179         self._soundpos = 0

   180 

   181     def close(self):

   182         if self._i_opened_the_file:

   183             self._i_opened_the_file.close()

   184             self._i_opened_the_file = None

   185         self._file = None

   186 

   187     def tell(self):

   188         return self._soundpos

   189 

   190     def getnchannels(self):

   191         return self._nchannels

   192 

   193     def getnframes(self):

   194         return self._nframes

   195 

   196     def getsampwidth(self):

   197         return self._sampwidth

   198 

   199     def getframerate(self):

   200         return self._framerate

   201 

   202     def getcomptype(self):

   203         return self._comptype

   204 

   205     def getcompname(self):

   206         return self._compname

   207 

   208     def getparams(self):

   209         return self.getnchannels(), self.getsampwidth(), \

   210                self.getframerate(), self.getnframes(), \

   211                self.getcomptype(), self.getcompname()

   212 

   213     def getmarkers(self):

   214         return None

   215 

   216     def getmark(self, id):

   217         raise Error, 'no marks'

   218 

   219     def setpos(self, pos):

   220         if pos < 0 or pos > self._nframes:

   221             raise Error, 'position not in range'

   222         self._soundpos = pos

   223         self._data_seek_needed = 1

   224 

   225     def readframes(self, nframes):

   226         if self._data_seek_needed:

   227             self._data_chunk.seek(0, 0)

   228             pos = self._soundpos * self._framesize

   229             if pos:

   230                 self._data_chunk.seek(pos, 0)

   231             self._data_seek_needed = 0

   232         if nframes == 0:

   233             return ''

   234         if self._sampwidth > 1 and big_endian:

   235             # unfortunately the fromfile() method does not take

   236             # something that only looks like a file object, so

   237             # we have to reach into the innards of the chunk object

   238             import array

   239             chunk = self._data_chunk

   240             data = array.array(_array_fmts[self._sampwidth])

   241             nitems = nframes * self._nchannels

   242             if nitems * self._sampwidth > chunk.chunksize - chunk.size_read:

   243                 nitems = (chunk.chunksize - chunk.size_read) / self._sampwidth

   244             data.fromfile(chunk.file.file, nitems)

   245             # "tell" data chunk how much was read

   246             chunk.size_read = chunk.size_read + nitems * self._sampwidth

   247             # do the same for the outermost chunk

   248             chunk = chunk.file

   249             chunk.size_read = chunk.size_read + nitems * self._sampwidth

   250             data.byteswap()

   251             data = data.tostring()

   252         else:

   253             data = self._data_chunk.read(nframes * self._framesize)

   254         if self._convert and data:

   255             data = self._convert(data)

   256         self._soundpos = self._soundpos + len(data) // (self._nchannels * self._sampwidth)

   257         return data

   258 

   259     #

   260     # Internal methods.

   261     #

   262 

   263     def _read_fmt_chunk(self, chunk):

   264         wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack('<hhllh', chunk.read(14))

   265         if wFormatTag == WAVE_FORMAT_PCM:

   266             sampwidth = struct.unpack('<h', chunk.read(2))[0]

   267             self._sampwidth = (sampwidth + 7) // 8

   268         else:

   269             raise Error, 'unknown format: %r' % (wFormatTag,)

   270         self._framesize = self._nchannels * self._sampwidth

   271         self._comptype = 'NONE'

   272         self._compname = 'not compressed'

   273 

   274 class Wave_write:

   275     """Variables used in this class:

   276 

   277     These variables are user settable through appropriate methods

   278     of this class:

   279     _file -- the open file with methods write(), close(), tell(), seek()

   280               set through the __init__() method

   281     _comptype -- the AIFF-C compression type ('NONE' in AIFF)

   282               set through the setcomptype() or setparams() method

   283     _compname -- the human-readable AIFF-C compression type

   284               set through the setcomptype() or setparams() method

   285     _nchannels -- the number of audio channels

   286               set through the setnchannels() or setparams() method

   287     _sampwidth -- the number of bytes per audio sample

   288               set through the setsampwidth() or setparams() method

   289     _framerate -- the sampling frequency

   290               set through the setframerate() or setparams() method

   291     _nframes -- the number of audio frames written to the header

   292               set through the setnframes() or setparams() method

   293 

   294     These variables are used internally only:

   295     _datalength -- the size of the audio samples written to the header

   296     _nframeswritten -- the number of frames actually written

   297     _datawritten -- the size of the audio samples actually written

   298     """

   299 

   300     def __init__(self, f):

   301         self._i_opened_the_file = None

   302         if isinstance(f, basestring):

   303             f = __builtin__.open(f, 'wb')

   304             self._i_opened_the_file = f

   305         try:

   306             self.initfp(f)

   307         except:

   308             if self._i_opened_the_file:

   309                 f.close()

   310             raise

   311 

   312     def initfp(self, file):

   313         self._file = file

   314         self._convert = None

   315         self._nchannels = 0

   316         self._sampwidth = 0

   317         self._framerate = 0

   318         self._nframes = 0

   319         self._nframeswritten = 0

   320         self._datawritten = 0

   321         self._datalength = 0

   322 

   323     def __del__(self):

   324         self.close()

   325 

   326     #

   327     # User visible methods.

   328     #

   329     def setnchannels(self, nchannels):

   330         if self._datawritten:

   331             raise Error, 'cannot change parameters after starting to write'

   332         if nchannels < 1:

   333             raise Error, 'bad # of channels'

   334         self._nchannels = nchannels

   335 

   336     def getnchannels(self):

   337         if not self._nchannels:

   338             raise Error, 'number of channels not set'

   339         return self._nchannels

   340 

   341     def setsampwidth(self, sampwidth):

   342         if self._datawritten:

   343             raise Error, 'cannot change parameters after starting to write'

   344         if sampwidth < 1 or sampwidth > 4:

   345             raise Error, 'bad sample width'

   346         self._sampwidth = sampwidth

   347 

   348     def getsampwidth(self):

   349         if not self._sampwidth:

   350             raise Error, 'sample width not set'

   351         return self._sampwidth

   352 

   353     def setframerate(self, framerate):

   354         if self._datawritten:

   355             raise Error, 'cannot change parameters after starting to write'

   356         if framerate <= 0:

   357             raise Error, 'bad frame rate'

   358         self._framerate = framerate

   359 

   360     def getframerate(self):

   361         if not self._framerate:

   362             raise Error, 'frame rate not set'

   363         return self._framerate

   364 

   365     def setnframes(self, nframes):

   366         if self._datawritten:

   367             raise Error, 'cannot change parameters after starting to write'

   368         self._nframes = nframes

   369 

   370     def getnframes(self):

   371         return self._nframeswritten

   372 

   373     def setcomptype(self, comptype, compname):

   374         if self._datawritten:

   375             raise Error, 'cannot change parameters after starting to write'

   376         if comptype not in ('NONE',):

   377             raise Error, 'unsupported compression type'

   378         self._comptype = comptype

   379         self._compname = compname

   380 

   381     def getcomptype(self):

   382         return self._comptype

   383 

   384     def getcompname(self):

   385         return self._compname

   386 

   387     def setparams(self, (nchannels, sampwidth, framerate, nframes, comptype, compname)):

   388         if self._datawritten:

   389             raise Error, 'cannot change parameters after starting to write'

   390         self.setnchannels(nchannels)

   391         self.setsampwidth(sampwidth)

   392         self.setframerate(framerate)

   393         self.setnframes(nframes)

   394         self.setcomptype(comptype, compname)

   395 

   396     def getparams(self):

   397         if not self._nchannels or not self._sampwidth or not self._framerate:

   398             raise Error, 'not all parameters set'

   399         return self._nchannels, self._sampwidth, self._framerate, \

   400               self._nframes, self._comptype, self._compname

   401 

   402     def setmark(self, id, pos, name):

   403         raise Error, 'setmark() not supported'

   404 

   405     def getmark(self, id):

   406         raise Error, 'no marks'

   407 

   408     def getmarkers(self):

   409         return None

   410 

   411     def tell(self):

   412         return self._nframeswritten

   413 

   414     def writeframesraw(self, data):

   415         self._ensure_header_written(len(data))

   416         nframes = len(data) // (self._sampwidth * self._nchannels)

   417         if self._convert:

   418             data = self._convert(data)

   419         if self._sampwidth > 1 and big_endian:

   420             import array

   421             data = array.array(_array_fmts[self._sampwidth], data)

   422             data.byteswap()

   423             data.tofile(self._file)

   424             self._datawritten = self._datawritten + len(data) * self._sampwidth

   425         else:

   426             self._file.write(data)

   427             self._datawritten = self._datawritten + len(data)

   428         self._nframeswritten = self._nframeswritten + nframes

   429 

   430     def writeframes(self, data):

   431         self.writeframesraw(data)

   432         if self._datalength != self._datawritten:

   433             self._patchheader()

   434 

   435     def close(self):

   436         if self._file:

   437             self._ensure_header_written(0)

   438             if self._datalength != self._datawritten:

   439                 self._patchheader()

   440             self._file.flush()

   441             self._file = None

   442         if self._i_opened_the_file:

   443             self._i_opened_the_file.close()

   444             self._i_opened_the_file = None

   445 

   446     #

   447     # Internal methods.

   448     #

   449 

   450     def _ensure_header_written(self, datasize):

   451         if not self._datawritten:

   452             if not self._nchannels:

   453                 raise Error, '# channels not specified'

   454             if not self._sampwidth:

   455                 raise Error, 'sample width not specified'

   456             if not self._framerate:

   457                 raise Error, 'sampling rate not specified'

   458             self._write_header(datasize)

   459 

   460     def _write_header(self, initlength):

   461         self._file.write('RIFF')

   462         if not self._nframes:

   463             self._nframes = initlength / (self._nchannels * self._sampwidth)

   464         self._datalength = self._nframes * self._nchannels * self._sampwidth

   465         self._form_length_pos = self._file.tell()

   466         self._file.write(struct.pack('<l4s4slhhllhh4s',

   467             36 + self._datalength, 'WAVE', 'fmt ', 16,

   468             WAVE_FORMAT_PCM, self._nchannels, self._framerate,

   469             self._nchannels * self._framerate * self._sampwidth,

   470             self._nchannels * self._sampwidth,

   471             self._sampwidth * 8, 'data'))

   472         self._data_length_pos = self._file.tell()

   473         self._file.write(struct.pack('<l', self._datalength))

   474 

   475     def _patchheader(self):

   476         if self._datawritten == self._datalength:

   477             return

   478         curpos = self._file.tell()

   479         self._file.seek(self._form_length_pos, 0)

   480         self._file.write(struct.pack('<l', 36 + self._datawritten))

   481         self._file.seek(self._data_length_pos, 0)

   482         self._file.write(struct.pack('<l', self._datawritten))

   483         self._file.seek(curpos, 0)

   484         self._datalength = self._datawritten

   485 

   486 def open(f, mode=None):

   487     if mode is None:

   488         if hasattr(f, 'mode'):

   489             mode = f.mode

   490         else:

   491             mode = 'rb'

   492     if mode in ('r', 'rb'):

   493         return Wave_read(f)

   494     elif mode in ('w', 'wb'):

   495         return Wave_write(f)

   496     else:

   497         raise Error, "mode must be 'r', 'rb', 'w', or 'wb'"

   498 

   499 openfp = open # B/W compatibility