"""Stuff to parse AIFF-C and AIFF files.

Unless explicitly stated otherwise, the description below is true

both for AIFF-C files and AIFF files.

An AIFF-C file has the following structure.

  +-----------------+

  | FORM            |

  +-----------------+

  | <size>          |

  +----+------------+

  |    | AIFC       |

  |    +------------+

  |    | <chunks>   |

  |    |    .       |

  |    |    .       |

  |    |    .       |

  +----+------------+

An AIFF file has the string "AIFF" instead of "AIFC".

A chunk consists of an identifier (4 bytes) followed by a size (4 bytes,

big endian order), followed by the data.  The size field does not include

the size of the 8 byte header.

The following chunk types are recognized.

  FVER

      <version number of AIFF-C defining document> (AIFF-C only).

  MARK

      <# of markers> (2 bytes)

      list of markers:

          <marker ID> (2 bytes, must be > 0)

          <position> (4 bytes)

          <marker name> ("pstring")

  COMM

      <# of channels> (2 bytes)

      <# of sound frames> (4 bytes)

      <size of the samples> (2 bytes)

      <sampling frequency> (10 bytes, IEEE 80-bit extended

          floating point)

      in AIFF-C files only:

      <compression type> (4 bytes)

      <human-readable version of compression type> ("pstring")

  SSND

      <offset> (4 bytes, not used by this program)

      <blocksize> (4 bytes, not used by this program)

      <sound data>

A pstring consists of 1 byte length, a string of characters, and 0 or 1

byte pad to make the total length even.

Usage.

Reading AIFF files:

  f = aifc.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().

In some types of audio files, if the setpos() method is 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()    -- get the list of marks in the audio file or None

             if there are no marks

  getmark(id) -- get mark with the specified id (raises an error

             if the mark does not exist)

  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(), the position given to setpos() and

the position of marks are all 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 AIFF files:

  f = aifc.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:

  aiff()      -- create an AIFF file (AIFF-C default)

  aifc()      -- create an AIFF-C file

  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

  setmark(id, pos, name)

          -- add specified mark to the list of marks

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

             in combination with setmark())

  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.

Marks can be added anytime.  If there are any marks, ypu must call

close() after all frames have been written.

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

is destroyed.

When a file is opened with the extension '.aiff', an AIFF file is

written, otherwise an AIFF-C file is written.  This default can be

changed by calling aiff() or aifc() before the first writeframes or

writeframesraw.

"""

import struct

import __builtin__

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

class Error(Exception):

    pass

_AIFC_version = 0xA2805140L     # Version 1 of AIFF-C

_skiplist = 'COMT', 'INST', 'MIDI', 'AESD', \

      'APPL', 'NAME', 'AUTH', '(c) ', 'ANNO'

def _read_long(file):

    try:

        return struct.unpack('>l', file.read(4))[0]

    except struct.error:

        raise EOFError

def _read_ulong(file):

    try:

        return struct.unpack('>L', file.read(4))[0]

    except struct.error:

        raise EOFError

def _read_short(file):

    try:

        return struct.unpack('>h', file.read(2))[0]

    except struct.error:

        raise EOFError

def _read_string(file):

    length = ord(file.read(1))

    if length == 0:

        data = ''

    else:

        data = file.read(length)

    if length & 1 == 0:

        dummy = file.read(1)

    return data

_HUGE_VAL = 1.79769313486231e+308 # See <limits.h>

def _read_float(f): # 10 bytes

    expon = _read_short(f) # 2 bytes

    sign = 1

    if expon < 0:

        sign = -1

        expon = expon + 0x8000

    himant = _read_ulong(f) # 4 bytes

    lomant = _read_ulong(f) # 4 bytes

    if expon == himant == lomant == 0:

        f = 0.0

    elif expon == 0x7FFF:

        f = _HUGE_VAL

    else:

        expon = expon - 16383

        f = (himant * 0x100000000L + lomant) * pow(2.0, expon - 63)

    return sign * f

def _write_short(f, x):

    f.write(struct.pack('>h', x))

def _write_long(f, x):

    f.write(struct.pack('>L', x))

def _write_string(f, s):

    if len(s) > 255:

        raise ValueError("string exceeds maximum pstring length")

    f.write(chr(len(s)))

    f.write(s)

    if len(s) & 1 == 0:

        f.write(chr(0))

def _write_float(f, x):

    import math

    if x < 0:

        sign = 0x8000

        x = x * -1

    else:

        sign = 0

    if x == 0:

        expon = 0

        himant = 0

        lomant = 0

    else:

        fmant, expon = math.frexp(x)

        if expon > 16384 or fmant >= 1:     # Infinity or NaN

            expon = sign|0x7FFF

            himant = 0

            lomant = 0

        else:                   # Finite

            expon = expon + 16382

            if expon < 0:           # denormalized

                fmant = math.ldexp(fmant, expon)

                expon = 0

            expon = expon | sign

            fmant = math.ldexp(fmant, 32)

            fsmant = math.floor(fmant)

            himant = long(fsmant)

            fmant = math.ldexp(fmant - fsmant, 32)

            fsmant = math.floor(fmant)

            lomant = long(fsmant)

    _write_short(f, expon)

    _write_long(f, himant)

    _write_long(f, lomant)

from chunk import Chunk

class Aifc_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

    # _markers -- the marks in the audio file

    #       available through the getmarkers() and getmark()

    #       methods

    # _soundpos -- the position in the audio stream

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

    #       setpos() method

    #

    # These variables are used internally only:

    # _version -- the AIFF-C version number

    # _decomp -- the decompressor from builtin module cl

    # _comm_chunk_read -- 1 iff the COMM chunk has been read

    # _aifc -- 1 iff reading an AIFF-C file

    # _ssnd_seek_needed -- 1 iff positioned correctly in audio

    #       file for readframes()

    # _ssnd_chunk -- instantiation of a chunk class for the SSND chunk

    # _framesize -- size of one frame in the file

    def initfp(self, file):

        self._version = 0

        self._decomp = None

        self._convert = None

        self._markers = []

        self._soundpos = 0

        self._file = Chunk(file)

        if self._file.getname() != 'FORM':

            raise Error, 'file does not start with FORM id'

        formdata = self._file.read(4)

        if formdata == 'AIFF':

            self._aifc = 0

        elif formdata == 'AIFC':

            self._aifc = 1

        else:

            raise Error, 'not an AIFF or AIFF-C file'

        self._comm_chunk_read = 0

        while 1:

            self._ssnd_seek_needed = 1

            try:

                chunk = Chunk(self._file)

            except EOFError:

                break

            chunkname = chunk.getname()

            if chunkname == 'COMM':

                self._read_comm_chunk(chunk)

                self._comm_chunk_read = 1

            elif chunkname == 'SSND':

                self._ssnd_chunk = chunk

                dummy = chunk.read(8)

                self._ssnd_seek_needed = 0

            elif chunkname == 'FVER':

                self._version = _read_ulong(chunk)

            elif chunkname == 'MARK':

                self._readmark(chunk)

            elif chunkname in _skiplist:

                pass

            else:

                raise Error, 'unrecognized chunk type '+chunk.chunkname

            chunk.skip()

        if not self._comm_chunk_read or not self._ssnd_chunk:

            raise Error, 'COMM chunk and/or SSND chunk missing'

        if self._aifc and self._decomp:

            import cl

            params = [cl.ORIGINAL_FORMAT, 0,

                  cl.BITS_PER_COMPONENT, self._sampwidth * 8,

                  cl.FRAME_RATE, self._framerate]

            if self._nchannels == 1:

                params[1] = cl.MONO

            elif self._nchannels == 2:

                params[1] = cl.STEREO_INTERLEAVED

            else:

                raise Error, 'cannot compress more than 2 channels'

            self._decomp.SetParams(params)

    def __init__(self, f):

        if type(f) == type(''):

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

        # else, assume it is an open file object already

        self.initfp(f)

    #

    # User visible methods.

    #

    def getfp(self):

        return self._file

    def rewind(self):

        self._ssnd_seek_needed = 1

        self._soundpos = 0

    def close(self):

        if self._decomp:

            self._decomp.CloseDecompressor()

            self._decomp = 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 getversion(self):

##      return self._version

    def getparams(self):

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

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

              self.getcomptype(), self.getcompname()

    def getmarkers(self):

        if len(self._markers) == 0:

            return None

        return self._markers

    def getmark(self, id):

        for marker in self._markers:

            if id == marker[0]:

                return marker

        raise Error, 'marker %r does not exist' % (id,)

    def setpos(self, pos):

        if pos < 0 or pos > self._nframes:

            raise Error, 'position not in range'

        self._soundpos = pos

        self._ssnd_seek_needed = 1

    def readframes(self, nframes):

        if self._ssnd_seek_needed:

            self._ssnd_chunk.seek(0)

            dummy = self._ssnd_chunk.read(8)

            pos = self._soundpos * self._framesize

            if pos:

                self._ssnd_chunk.seek(pos + 8)

            self._ssnd_seek_needed = 0

        if nframes == 0:

            return ''

        data = self._ssnd_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 _decomp_data(self, data):

        import cl

        dummy = self._decomp.SetParam(cl.FRAME_BUFFER_SIZE,

                          len(data) * 2)

        return self._decomp.Decompress(len(data) / self._nchannels,

                           data)

    def _ulaw2lin(self, data):

        import audioop

        return audioop.ulaw2lin(data, 2)

    def _adpcm2lin(self, data):

        import audioop

        if not hasattr(self, '_adpcmstate'):

            # first time

            self._adpcmstate = None

        data, self._adpcmstate = audioop.adpcm2lin(data, 2,

                               self._adpcmstate)

        return data

    def _read_comm_chunk(self, chunk):

        self._nchannels = _read_short(chunk)

        self._nframes = _read_long(chunk)

        self._sampwidth = (_read_short(chunk) + 7) / 8

        self._framerate = int(_read_float(chunk))

        self._framesize = self._nchannels * self._sampwidth

        if self._aifc:

            #DEBUG: SGI's soundeditor produces a bad size :-(

            kludge = 0

            if chunk.chunksize == 18:

                kludge = 1

                print 'Warning: bad COMM chunk size'

                chunk.chunksize = 23

            #DEBUG end

            self._comptype = chunk.read(4)

            #DEBUG start

            if kludge:

                length = ord(chunk.file.read(1))

                if length & 1 == 0:

                    length = length + 1

                chunk.chunksize = chunk.chunksize + length

                chunk.file.seek(-1, 1)

            #DEBUG end

            self._compname = _read_string(chunk)

            if self._comptype != 'NONE':

                if self._comptype == 'G722':

                    try:

                        import audioop

                    except ImportError:

                        pass

                    else:

                        self._convert = self._adpcm2lin

                        self._framesize = self._framesize / 4

                        return

                # for ULAW and ALAW try Compression Library

                try:

                    import cl

                except ImportError:

                    if self._comptype == 'ULAW':

                        try:

                            import audioop

                            self._convert = self._ulaw2lin

                            self._framesize = self._framesize / 2

                            return

                        except ImportError:

                            pass

                    raise Error, 'cannot read compressed AIFF-C files'

                if self._comptype == 'ULAW':

                    scheme = cl.G711_ULAW

                    self._framesize = self._framesize / 2

                elif self._comptype == 'ALAW':

                    scheme = cl.G711_ALAW

                    self._framesize = self._framesize / 2

                else:

                    raise Error, 'unsupported compression type'

                self._decomp = cl.OpenDecompressor(scheme)

                self._convert = self._decomp_data

        else:

            self._comptype = 'NONE'

            self._compname = 'not compressed'

    def _readmark(self, chunk):

        nmarkers = _read_short(chunk)

        # Some files appear to contain invalid counts.

        # Cope with this by testing for EOF.

        try:

            for i in range(nmarkers):

                id = _read_short(chunk)

                pos = _read_long(chunk)

                name = _read_string(chunk)

                if pos or name:

                    # some files appear to have

                    # dummy markers consisting of

                    # a position 0 and name ''

                    self._markers.append((id, pos, name))

        except EOFError:

            print 'Warning: MARK chunk contains only',

            print len(self._markers),

            if len(self._markers) == 1: print 'marker',

            else: print 'markers',

            print 'instead of', nmarkers

class Aifc_write:

    # Variables used in this class: