"""Stuff to parse Sun and NeXT audio files.

An audio file consists of a header followed by the data.  The structure

of the header is as follows.

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

        | magic word    |

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

        | header size   |

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

        | data size     |

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

        | encoding      |

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

        | sample rate   |

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

        | # of channels |

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

        | info          |

        |               |

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

The magic word consists of the 4 characters '.snd'.  Apart from the

info field, all header fields are 4 bytes in size.  They are all

32-bit unsigned integers encoded in big-endian byte order.

The header size really gives the start of the data.

The data size is the physical size of the data.  From the other

parameters the number of frames can be calculated.

The encoding gives the way in which audio samples are encoded.

Possible values are listed below.

The info field currently consists of an ASCII string giving a

human-readable description of the audio file.  The info field is

padded with NUL bytes to the header size.

Usage.

Reading audio files:

        f = sunau.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' or 'ULAW')

        getcompname()   -- returns human-readable version of

                           compression type ('not compressed' matches 'NONE')

        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 audio files:

        f = sunau.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.

"""

# from <multimedia/audio_filehdr.h>

AUDIO_FILE_MAGIC = 0x2e736e64

AUDIO_FILE_ENCODING_MULAW_8 = 1

AUDIO_FILE_ENCODING_LINEAR_8 = 2

AUDIO_FILE_ENCODING_LINEAR_16 = 3

AUDIO_FILE_ENCODING_LINEAR_24 = 4

AUDIO_FILE_ENCODING_LINEAR_32 = 5

AUDIO_FILE_ENCODING_FLOAT = 6

AUDIO_FILE_ENCODING_DOUBLE = 7

AUDIO_FILE_ENCODING_ADPCM_G721 = 23

AUDIO_FILE_ENCODING_ADPCM_G722 = 24

AUDIO_FILE_ENCODING_ADPCM_G723_3 = 25

AUDIO_FILE_ENCODING_ADPCM_G723_5 = 26

AUDIO_FILE_ENCODING_ALAW_8 = 27

# from <multimedia/audio_hdr.h>

AUDIO_UNKNOWN_SIZE = 0xFFFFFFFFL        # ((unsigned)(~0))

_simple_encodings = [AUDIO_FILE_ENCODING_MULAW_8,

                     AUDIO_FILE_ENCODING_LINEAR_8,

                     AUDIO_FILE_ENCODING_LINEAR_16,

                     AUDIO_FILE_ENCODING_LINEAR_24,

                     AUDIO_FILE_ENCODING_LINEAR_32,

                     AUDIO_FILE_ENCODING_ALAW_8]

class Error(Exception):

    pass

def _read_u32(file):

    x = 0L

    for i in range(4):

        byte = file.read(1)

        if byte == '':

            raise EOFError

        x = x*256 + ord(byte)

    return x

def _write_u32(file, x):

    data = []

    for i in range(4):

        d, m = divmod(x, 256)

        data.insert(0, m)

        x = d

    for i in range(4):

        file.write(chr(int(data[i])))

class Au_read:

    def __init__(self, f):

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

            import __builtin__

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

        self.initfp(f)

    def __del__(self):

        if self._file:

            self.close()

    def initfp(self, file):

        self._file = file

        self._soundpos = 0

        magic = int(_read_u32(file))

        if magic != AUDIO_FILE_MAGIC:

            raise Error, 'bad magic number'

        self._hdr_size = int(_read_u32(file))

        if self._hdr_size < 24:

            raise Error, 'header size too small'

        if self._hdr_size > 100:

            raise Error, 'header size ridiculously large'

        self._data_size = _read_u32(file)

        if self._data_size != AUDIO_UNKNOWN_SIZE:

            self._data_size = int(self._data_size)

        self._encoding = int(_read_u32(file))

        if self._encoding not in _simple_encodings:

            raise Error, 'encoding not (yet) supported'

        if self._encoding in (AUDIO_FILE_ENCODING_MULAW_8,

                  AUDIO_FILE_ENCODING_ALAW_8):

            self._sampwidth = 2

            self._framesize = 1

        elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_8:

            self._framesize = self._sampwidth = 1

        elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_16:

            self._framesize = self._sampwidth = 2

        elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_24:

            self._framesize = self._sampwidth = 3

        elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_32:

            self._framesize = self._sampwidth = 4

        else:

            raise Error, 'unknown encoding'

        self._framerate = int(_read_u32(file))

        self._nchannels = int(_read_u32(file))

        self._framesize = self._framesize * self._nchannels

        if self._hdr_size > 24:

            self._info = file.read(self._hdr_size - 24)

            for i in range(len(self._info)):

                if self._info[i] == '\0':

                    self._info = self._info[:i]

                    break

        else:

            self._info = ''

    def getfp(self):

        return self._file

    def getnchannels(self):

        return self._nchannels

    def getsampwidth(self):

        return self._sampwidth

    def getframerate(self):

        return self._framerate

    def getnframes(self):

        if self._data_size == AUDIO_UNKNOWN_SIZE:

            return AUDIO_UNKNOWN_SIZE

        if self._encoding in _simple_encodings:

            return self._data_size / self._framesize

        return 0                # XXX--must do some arithmetic here

    def getcomptype(self):

        if self._encoding == AUDIO_FILE_ENCODING_MULAW_8:

            return 'ULAW'

        elif self._encoding == AUDIO_FILE_ENCODING_ALAW_8:

            return 'ALAW'

        else:

            return 'NONE'

    def getcompname(self):

        if self._encoding == AUDIO_FILE_ENCODING_MULAW_8:

            return 'CCITT G.711 u-law'

        elif self._encoding == AUDIO_FILE_ENCODING_ALAW_8:

            return 'CCITT G.711 A-law'

        else:

            return 'not compressed'

    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 readframes(self, nframes):

        if self._encoding in _simple_encodings:

            if nframes == AUDIO_UNKNOWN_SIZE:

                data = self._file.read()

            else:

                data = self._file.read(nframes * self._framesize * self._nchannels)

            if self._encoding == AUDIO_FILE_ENCODING_MULAW_8:

                import audioop

                data = audioop.ulaw2lin(data, self._sampwidth)

            return data

        return None             # XXX--not implemented yet

    def rewind(self):

        self._soundpos = 0

        self._file.seek(self._hdr_size)

    def tell(self):

        return self._soundpos

    def setpos(self, pos):

        if pos < 0 or pos > self.getnframes():

            raise Error, 'position not in range'

        self._file.seek(pos * self._framesize + self._hdr_size)

        self._soundpos = pos

    def close(self):

        self._file = None

class Au_write:

    def __init__(self, f):

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

            import __builtin__

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

        self.initfp(f)

    def __del__(self):

        if self._file:

            self.close()

    def initfp(self, file):

        self._file = file

        self._framerate = 0

        self._nchannels = 0

        self._sampwidth = 0

        self._framesize = 0

        self._nframes = AUDIO_UNKNOWN_SIZE

        self._nframeswritten = 0

        self._datawritten = 0

        self._datalength = 0

        self._info = ''

        self._comptype = 'ULAW' # default is U-law

    def setnchannels(self, nchannels):

        if self._nframeswritten:

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

        if nchannels not in (1, 2, 4):

            raise Error, 'only 1, 2, or 4 channels supported'

        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._nframeswritten:

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

        if sampwidth not in (1, 2, 4):

            raise Error, 'bad sample width'

        self._sampwidth = sampwidth

    def getsampwidth(self):

        if not self._framerate:

            raise Error, 'sample width not specified'

        return self._sampwidth

    def setframerate(self, framerate):

        if self._nframeswritten:

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

        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._nframeswritten:

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

        if nframes < 0:

            raise Error, '# of frames cannot be negative'

        self._nframes = nframes

    def getnframes(self):

        return self._nframeswritten

    def setcomptype(self, type, name):

        if type in ('NONE', 'ULAW'):

            self._comptype = type

        else:

            raise Error, 'unknown compression type'

    def getcomptype(self):

        return self._comptype

    def getcompname(self):

        if self._comptype == 'ULAW':

            return 'CCITT G.711 u-law'

        elif self._comptype == 'ALAW':

            return 'CCITT G.711 A-law'

        else:

            return 'not compressed'

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

        self.setnchannels(nchannels)

        self.setsampwidth(sampwidth)

        self.setframerate(framerate)

        self.setnframes(nframes)

        self.setcomptype(comptype, compname)

    def getparams(self):

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

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

                  self.getcomptype(), self.getcompname()

    def tell(self):

        return self._nframeswritten

    def writeframesraw(self, data):

        self._ensure_header_written()

        nframes = len(data) / self._framesize

        if self._comptype == 'ULAW':

            import audioop

            data = audioop.lin2ulaw(data, self._sampwidth)

        self._file.write(data)

        self._nframeswritten = self._nframeswritten + nframes

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

    def writeframes(self, data):

        self.writeframesraw(data)

        if self._nframeswritten != self._nframes or \

                  self._datalength != self._datawritten:

            self._patchheader()

    def close(self):

        self._ensure_header_written()

        if self._nframeswritten != self._nframes or \

                  self._datalength != self._datawritten:

            self._patchheader()

        self._file.flush()

        self._file = None

    #

    # private methods

    #

    def _ensure_header_written(self):

        if not self._nframeswritten:

            if not self._nchannels:

                raise Error, '# of channels not specified'

            if not self._sampwidth:

                raise Error, 'sample width not specified'

            if not self._framerate:

                raise Error, 'frame rate not specified'

            self._write_header()

    def _write_header(self):

        if self._comptype == 'NONE':

            if self._sampwidth == 1:

                encoding = AUDIO_FILE_ENCODING_LINEAR_8

                self._framesize = 1

            elif self._sampwidth == 2:

                encoding = AUDIO_FILE_ENCODING_LINEAR_16

                self._framesize = 2

            elif self._sampwidth == 4:

                encoding = AUDIO_FILE_ENCODING_LINEAR_32

                self._framesize = 4

            else:

                raise Error, 'internal error'

        elif self._comptype == 'ULAW':

            encoding = AUDIO_FILE_ENCODING_MULAW_8

            self._framesize = 1

        else:

            raise Error, 'internal error'

        self._framesize = self._framesize * self._nchannels

        _write_u32(self._file, AUDIO_FILE_MAGIC)

        header_size = 25 + len(self._info)

        header_size = (header_size + 7) & ~7

        _write_u32(self._file, header_size)

        if self._nframes == AUDIO_UNKNOWN_SIZE:

            length = AUDIO_UNKNOWN_SIZE

        else:

            length = self._nframes * self._framesize

        _write_u32(self._file, length)

        self._datalength = length

        _write_u32(self._file, encoding)

        _write_u32(self._file, self._framerate)

        _write_u32(self._file, self._nchannels)

        self._file.write(self._info)

        self._file.write('\0'*(header_size - len(self._info) - 24))

    def _patchheader(self):

        self._file.seek(8)

        _write_u32(self._file, self._datawritten)

        self._datalength = self._datawritten

        self._file.seek(0, 2)

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 Au_read(f)

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

        return Au_write(f)

    else:

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

openfp = open