"""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, 'l'

# Determine endian-ness

import struct

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

    big_endian = 1

else:

    big_endian = 0

from chunk import Chunk

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):

        if self._i_opened_the_file:

            self._i_opened_the_file.close()

            self._i_opened_the_file = None

        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.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 > 1 and big_endian:

            # 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])

            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._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

    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, (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 and big_endian:

            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):

        if self._file:

            self._ensure_header_written(0)

            if self._datalength != self._datawritten:

                self._patchheader()

            self._file.flush()

            self._file = None

        if self._i_opened_the_file:

            self._i_opened_the_file.close()

            self._i_opened_the_file = None

    #

    # Internal methods.

    #

    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()

        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))

    def _patchheader(self):

        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