| 1 | """Stuff to parse Sun and NeXT audio files.
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| 2 |
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| 3 | An audio file consists of a header followed by the data. The structure
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| 4 | of the header is as follows.
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| 5 |
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| 6 | +---------------+
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| 7 | | magic word |
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| 8 | +---------------+
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| 9 | | header size |
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| 10 | +---------------+
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| 11 | | data size |
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| 12 | +---------------+
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| 13 | | encoding |
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| 14 | +---------------+
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| 15 | | sample rate |
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| 16 | +---------------+
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| 17 | | # of channels |
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| 18 | +---------------+
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| 19 | | info |
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| 20 | | |
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| 21 | +---------------+
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| 22 |
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| 23 | The magic word consists of the 4 characters '.snd'. Apart from the
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| 24 | info field, all header fields are 4 bytes in size. They are all
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| 25 | 32-bit unsigned integers encoded in big-endian byte order.
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| 26 |
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| 27 | The header size really gives the start of the data.
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| 28 | The data size is the physical size of the data. From the other
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| 29 | parameters the number of frames can be calculated.
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| 30 | The encoding gives the way in which audio samples are encoded.
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| 31 | Possible values are listed below.
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| 32 | The info field currently consists of an ASCII string giving a
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| 33 | human-readable description of the audio file. The info field is
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| 34 | padded with NUL bytes to the header size.
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| 35 |
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| 36 | Usage.
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| 37 |
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| 38 | Reading audio files:
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| 39 | f = sunau.open(file, 'r')
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| 40 | where file is either the name of a file or an open file pointer.
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| 41 | The open file pointer must have methods read(), seek(), and close().
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| 42 | When the setpos() and rewind() methods are not used, the seek()
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| 43 | method is not necessary.
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| 44 |
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| 45 | This returns an instance of a class with the following public methods:
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| 46 | getnchannels() -- returns number of audio channels (1 for
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| 47 | mono, 2 for stereo)
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| 48 | getsampwidth() -- returns sample width in bytes
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| 49 | getframerate() -- returns sampling frequency
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| 50 | getnframes() -- returns number of audio frames
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| 51 | getcomptype() -- returns compression type ('NONE' or 'ULAW')
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| 52 | getcompname() -- returns human-readable version of
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| 53 | compression type ('not compressed' matches 'NONE')
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| 54 | getparams() -- returns a tuple consisting of all of the
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| 55 | above in the above order
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| 56 | getmarkers() -- returns None (for compatibility with the
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| 57 | aifc module)
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| 58 | getmark(id) -- raises an error since the mark does not
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| 59 | exist (for compatibility with the aifc module)
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| 60 | readframes(n) -- returns at most n frames of audio
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| 61 | rewind() -- rewind to the beginning of the audio stream
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| 62 | setpos(pos) -- seek to the specified position
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| 63 | tell() -- return the current position
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| 64 | close() -- close the instance (make it unusable)
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| 65 | The position returned by tell() and the position given to setpos()
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| 66 | are compatible and have nothing to do with the actual position in the
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| 67 | file.
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| 68 | The close() method is called automatically when the class instance
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| 69 | is destroyed.
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| 70 |
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| 71 | Writing audio files:
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| 72 | f = sunau.open(file, 'w')
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| 73 | where file is either the name of a file or an open file pointer.
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| 74 | The open file pointer must have methods write(), tell(), seek(), and
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| 75 | close().
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| 76 |
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| 77 | This returns an instance of a class with the following public methods:
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| 78 | setnchannels(n) -- set the number of channels
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| 79 | setsampwidth(n) -- set the sample width
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| 80 | setframerate(n) -- set the frame rate
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| 81 | setnframes(n) -- set the number of frames
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| 82 | setcomptype(type, name)
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| 83 | -- set the compression type and the
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| 84 | human-readable compression type
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| 85 | setparams(tuple)-- set all parameters at once
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| 86 | tell() -- return current position in output file
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| 87 | writeframesraw(data)
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| 88 | -- write audio frames without pathing up the
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| 89 | file header
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| 90 | writeframes(data)
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| 91 | -- write audio frames and patch up the file header
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| 92 | close() -- patch up the file header and close the
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| 93 | output file
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| 94 | You should set the parameters before the first writeframesraw or
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| 95 | writeframes. The total number of frames does not need to be set,
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| 96 | but when it is set to the correct value, the header does not have to
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| 97 | be patched up.
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| 98 | It is best to first set all parameters, perhaps possibly the
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| 99 | compression type, and then write audio frames using writeframesraw.
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| 100 | When all frames have been written, either call writeframes('') or
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| 101 | close() to patch up the sizes in the header.
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| 102 | The close() method is called automatically when the class instance
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| 103 | is destroyed.
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| 104 | """
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| 105 |
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| 106 | # from <multimedia/audio_filehdr.h>
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| 107 | AUDIO_FILE_MAGIC = 0x2e736e64
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| 108 | AUDIO_FILE_ENCODING_MULAW_8 = 1
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| 109 | AUDIO_FILE_ENCODING_LINEAR_8 = 2
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| 110 | AUDIO_FILE_ENCODING_LINEAR_16 = 3
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| 111 | AUDIO_FILE_ENCODING_LINEAR_24 = 4
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| 112 | AUDIO_FILE_ENCODING_LINEAR_32 = 5
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| 113 | AUDIO_FILE_ENCODING_FLOAT = 6
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| 114 | AUDIO_FILE_ENCODING_DOUBLE = 7
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| 115 | AUDIO_FILE_ENCODING_ADPCM_G721 = 23
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| 116 | AUDIO_FILE_ENCODING_ADPCM_G722 = 24
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| 117 | AUDIO_FILE_ENCODING_ADPCM_G723_3 = 25
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| 118 | AUDIO_FILE_ENCODING_ADPCM_G723_5 = 26
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| 119 | AUDIO_FILE_ENCODING_ALAW_8 = 27
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| 120 |
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| 121 | # from <multimedia/audio_hdr.h>
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| 122 | AUDIO_UNKNOWN_SIZE = 0xFFFFFFFFL # ((unsigned)(~0))
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| 123 |
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| 124 | _simple_encodings = [AUDIO_FILE_ENCODING_MULAW_8,
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| 125 | AUDIO_FILE_ENCODING_LINEAR_8,
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| 126 | AUDIO_FILE_ENCODING_LINEAR_16,
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| 127 | AUDIO_FILE_ENCODING_LINEAR_24,
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| 128 | AUDIO_FILE_ENCODING_LINEAR_32,
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| 129 | AUDIO_FILE_ENCODING_ALAW_8]
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| 130 |
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| 131 | class Error(Exception):
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| 132 | pass
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| 133 |
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| 134 | def _read_u32(file):
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| 135 | x = 0L
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| 136 | for i in range(4):
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| 137 | byte = file.read(1)
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| 138 | if byte == '':
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| 139 | raise EOFError
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| 140 | x = x*256 + ord(byte)
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| 141 | return x
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| 142 |
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| 143 | def _write_u32(file, x):
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| 144 | data = []
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| 145 | for i in range(4):
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| 146 | d, m = divmod(x, 256)
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| 147 | data.insert(0, m)
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| 148 | x = d
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| 149 | for i in range(4):
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| 150 | file.write(chr(int(data[i])))
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| 151 |
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| 152 | class Au_read:
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| 153 |
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| 154 | def __init__(self, f):
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| 155 | if type(f) == type(''):
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| 156 | import __builtin__
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| 157 | f = __builtin__.open(f, 'rb')
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| 158 | self.initfp(f)
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| 159 |
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| 160 | def __del__(self):
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| 161 | if self._file:
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| 162 | self.close()
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| 163 |
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| 164 | def initfp(self, file):
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| 165 | self._file = file
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| 166 | self._soundpos = 0
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| 167 | magic = int(_read_u32(file))
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| 168 | if magic != AUDIO_FILE_MAGIC:
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| 169 | raise Error, 'bad magic number'
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| 170 | self._hdr_size = int(_read_u32(file))
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| 171 | if self._hdr_size < 24:
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| 172 | raise Error, 'header size too small'
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| 173 | if self._hdr_size > 100:
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| 174 | raise Error, 'header size ridiculously large'
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| 175 | self._data_size = _read_u32(file)
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| 176 | if self._data_size != AUDIO_UNKNOWN_SIZE:
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| 177 | self._data_size = int(self._data_size)
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| 178 | self._encoding = int(_read_u32(file))
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| 179 | if self._encoding not in _simple_encodings:
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| 180 | raise Error, 'encoding not (yet) supported'
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| 181 | if self._encoding in (AUDIO_FILE_ENCODING_MULAW_8,
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| 182 | AUDIO_FILE_ENCODING_ALAW_8):
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| 183 | self._sampwidth = 2
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| 184 | self._framesize = 1
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| 185 | elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_8:
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| 186 | self._framesize = self._sampwidth = 1
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| 187 | elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_16:
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| 188 | self._framesize = self._sampwidth = 2
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| 189 | elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_24:
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| 190 | self._framesize = self._sampwidth = 3
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| 191 | elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_32:
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| 192 | self._framesize = self._sampwidth = 4
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| 193 | else:
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| 194 | raise Error, 'unknown encoding'
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| 195 | self._framerate = int(_read_u32(file))
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| 196 | self._nchannels = int(_read_u32(file))
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| 197 | self._framesize = self._framesize * self._nchannels
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| 198 | if self._hdr_size > 24:
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| 199 | self._info = file.read(self._hdr_size - 24)
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| 200 | for i in range(len(self._info)):
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| 201 | if self._info[i] == '\0':
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| 202 | self._info = self._info[:i]
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| 203 | break
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| 204 | else:
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| 205 | self._info = ''
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| 206 | try:
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| 207 | self._data_pos = file.tell()
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| 208 | except (AttributeError, IOError):
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| 209 | self._data_pos = None
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| 210 |
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| 211 | def getfp(self):
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| 212 | return self._file
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| 213 |
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| 214 | def getnchannels(self):
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| 215 | return self._nchannels
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| 216 |
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| 217 | def getsampwidth(self):
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| 218 | return self._sampwidth
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| 219 |
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| 220 | def getframerate(self):
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| 221 | return self._framerate
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| 222 |
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| 223 | def getnframes(self):
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| 224 | if self._data_size == AUDIO_UNKNOWN_SIZE:
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| 225 | return AUDIO_UNKNOWN_SIZE
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| 226 | if self._encoding in _simple_encodings:
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| 227 | return self._data_size / self._framesize
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| 228 | return 0 # XXX--must do some arithmetic here
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| 229 |
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| 230 | def getcomptype(self):
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| 231 | if self._encoding == AUDIO_FILE_ENCODING_MULAW_8:
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| 232 | return 'ULAW'
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| 233 | elif self._encoding == AUDIO_FILE_ENCODING_ALAW_8:
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| 234 | return 'ALAW'
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| 235 | else:
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| 236 | return 'NONE'
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| 237 |
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| 238 | def getcompname(self):
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| 239 | if self._encoding == AUDIO_FILE_ENCODING_MULAW_8:
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| 240 | return 'CCITT G.711 u-law'
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| 241 | elif self._encoding == AUDIO_FILE_ENCODING_ALAW_8:
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| 242 | return 'CCITT G.711 A-law'
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| 243 | else:
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| 244 | return 'not compressed'
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| 245 |
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| 246 | def getparams(self):
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| 247 | return self.getnchannels(), self.getsampwidth(), \
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| 248 | self.getframerate(), self.getnframes(), \
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| 249 | self.getcomptype(), self.getcompname()
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| 250 |
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| 251 | def getmarkers(self):
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| 252 | return None
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| 253 |
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| 254 | def getmark(self, id):
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| 255 | raise Error, 'no marks'
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| 256 |
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| 257 | def readframes(self, nframes):
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| 258 | if self._encoding in _simple_encodings:
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| 259 | if nframes == AUDIO_UNKNOWN_SIZE:
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| 260 | data = self._file.read()
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| 261 | else:
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| 262 | data = self._file.read(nframes * self._framesize)
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| 263 | self._soundpos += len(data) // self._framesize
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| 264 | if self._encoding == AUDIO_FILE_ENCODING_MULAW_8:
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| 265 | import audioop
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| 266 | data = audioop.ulaw2lin(data, self._sampwidth)
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| 267 | return data
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| 268 | return None # XXX--not implemented yet
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| 269 |
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| 270 | def rewind(self):
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| 271 | if self._data_pos is None:
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| 272 | raise IOError('cannot seek')
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| 273 | self._file.seek(self._data_pos)
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| 274 | self._soundpos = 0
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| 275 |
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| 276 | def tell(self):
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| 277 | return self._soundpos
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| 278 |
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| 279 | def setpos(self, pos):
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| 280 | if pos < 0 or pos > self.getnframes():
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| 281 | raise Error, 'position not in range'
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| 282 | if self._data_pos is None:
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| 283 | raise IOError('cannot seek')
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| 284 | self._file.seek(self._data_pos + pos * self._framesize)
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| 285 | self._soundpos = pos
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| 286 |
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| 287 | def close(self):
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| 288 | self._file = None
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| 289 |
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| 290 | class Au_write:
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| 291 |
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| 292 | def __init__(self, f):
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| 293 | if type(f) == type(''):
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| 294 | import __builtin__
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| 295 | f = __builtin__.open(f, 'wb')
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| 296 | self.initfp(f)
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| 297 |
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| 298 | def __del__(self):
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| 299 | if self._file:
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| 300 | self.close()
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| 301 |
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| 302 | def initfp(self, file):
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| 303 | self._file = file
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| 304 | self._framerate = 0
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| 305 | self._nchannels = 0
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| 306 | self._sampwidth = 0
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| 307 | self._framesize = 0
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| 308 | self._nframes = AUDIO_UNKNOWN_SIZE
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| 309 | self._nframeswritten = 0
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| 310 | self._datawritten = 0
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| 311 | self._datalength = 0
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| 312 | self._info = ''
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| 313 | self._comptype = 'ULAW' # default is U-law
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| 314 |
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| 315 | def setnchannels(self, nchannels):
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| 316 | if self._nframeswritten:
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| 317 | raise Error, 'cannot change parameters after starting to write'
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| 318 | if nchannels not in (1, 2, 4):
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| 319 | raise Error, 'only 1, 2, or 4 channels supported'
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| 320 | self._nchannels = nchannels
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| 321 |
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| 322 | def getnchannels(self):
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| 323 | if not self._nchannels:
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| 324 | raise Error, 'number of channels not set'
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| 325 | return self._nchannels
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| 326 |
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| 327 | def setsampwidth(self, sampwidth):
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| 328 | if self._nframeswritten:
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| 329 | raise Error, 'cannot change parameters after starting to write'
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| 330 | if sampwidth not in (1, 2, 4):
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| 331 | raise Error, 'bad sample width'
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| 332 | self._sampwidth = sampwidth
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| 333 |
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| 334 | def getsampwidth(self):
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| 335 | if not self._framerate:
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| 336 | raise Error, 'sample width not specified'
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| 337 | return self._sampwidth
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| 338 |
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| 339 | def setframerate(self, framerate):
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| 340 | if self._nframeswritten:
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| 341 | raise Error, 'cannot change parameters after starting to write'
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| 342 | self._framerate = framerate
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| 343 |
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| 344 | def getframerate(self):
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| 345 | if not self._framerate:
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| 346 | raise Error, 'frame rate not set'
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| 347 | return self._framerate
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| 348 |
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| 349 | def setnframes(self, nframes):
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| 350 | if self._nframeswritten:
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| 351 | raise Error, 'cannot change parameters after starting to write'
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| 352 | if nframes < 0:
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| 353 | raise Error, '# of frames cannot be negative'
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| 354 | self._nframes = nframes
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| 355 |
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| 356 | def getnframes(self):
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| 357 | return self._nframeswritten
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| 358 |
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| 359 | def setcomptype(self, type, name):
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| 360 | if type in ('NONE', 'ULAW'):
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| 361 | self._comptype = type
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| 362 | else:
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| 363 | raise Error, 'unknown compression type'
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| 364 |
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| 365 | def getcomptype(self):
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| 366 | return self._comptype
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| 367 |
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| 368 | def getcompname(self):
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| 369 | if self._comptype == 'ULAW':
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| 370 | return 'CCITT G.711 u-law'
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| 371 | elif self._comptype == 'ALAW':
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| 372 | return 'CCITT G.711 A-law'
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| 373 | else:
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| 374 | return 'not compressed'
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| 375 |
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| 376 | def setparams(self, params):
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| 377 | nchannels, sampwidth, framerate, nframes, comptype, compname = params
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| 378 | self.setnchannels(nchannels)
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| 379 | self.setsampwidth(sampwidth)
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| 380 | self.setframerate(framerate)
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| 381 | self.setnframes(nframes)
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| 382 | self.setcomptype(comptype, compname)
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| 383 |
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| 384 | def getparams(self):
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| 385 | return self.getnchannels(), self.getsampwidth(), \
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| 386 | self.getframerate(), self.getnframes(), \
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| 387 | self.getcomptype(), self.getcompname()
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| 388 |
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| 389 | def tell(self):
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| 390 | return self._nframeswritten
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| 391 |
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| 392 | def writeframesraw(self, data):
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| 393 | self._ensure_header_written()
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| 394 | if self._comptype == 'ULAW':
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| 395 | import audioop
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| 396 | data = audioop.lin2ulaw(data, self._sampwidth)
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| 397 | nframes = len(data) // self._framesize
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| 398 | self._file.write(data)
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| 399 | self._nframeswritten = self._nframeswritten + nframes
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| 400 | self._datawritten = self._datawritten + len(data)
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| 401 |
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| 402 | def writeframes(self, data):
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| 403 | self.writeframesraw(data)
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| 404 | if self._nframeswritten != self._nframes or \
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| 405 | self._datalength != self._datawritten:
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| 406 | self._patchheader()
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| 407 |
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|---|
| 408 | def close(self):
|
|---|
| 409 | if self._file:
|
|---|
| 410 | try:
|
|---|
| 411 | self._ensure_header_written()
|
|---|
| 412 | if self._nframeswritten != self._nframes or \
|
|---|
| 413 | self._datalength != self._datawritten:
|
|---|
| 414 | self._patchheader()
|
|---|
| 415 | self._file.flush()
|
|---|
| 416 | finally:
|
|---|
| 417 | self._file = None
|
|---|
| 418 |
|
|---|
| 419 | #
|
|---|
| 420 | # private methods
|
|---|
| 421 | #
|
|---|
| 422 |
|
|---|
| 423 | def _ensure_header_written(self):
|
|---|
| 424 | if not self._nframeswritten:
|
|---|
| 425 | if not self._nchannels:
|
|---|
| 426 | raise Error, '# of channels not specified'
|
|---|
| 427 | if not self._sampwidth:
|
|---|
| 428 | raise Error, 'sample width not specified'
|
|---|
| 429 | if not self._framerate:
|
|---|
| 430 | raise Error, 'frame rate not specified'
|
|---|
| 431 | self._write_header()
|
|---|
| 432 |
|
|---|
| 433 | def _write_header(self):
|
|---|
| 434 | if self._comptype == 'NONE':
|
|---|
| 435 | if self._sampwidth == 1:
|
|---|
| 436 | encoding = AUDIO_FILE_ENCODING_LINEAR_8
|
|---|
| 437 | self._framesize = 1
|
|---|
| 438 | elif self._sampwidth == 2:
|
|---|
| 439 | encoding = AUDIO_FILE_ENCODING_LINEAR_16
|
|---|
| 440 | self._framesize = 2
|
|---|
| 441 | elif self._sampwidth == 4:
|
|---|
| 442 | encoding = AUDIO_FILE_ENCODING_LINEAR_32
|
|---|
| 443 | self._framesize = 4
|
|---|
| 444 | else:
|
|---|
| 445 | raise Error, 'internal error'
|
|---|
| 446 | elif self._comptype == 'ULAW':
|
|---|
| 447 | encoding = AUDIO_FILE_ENCODING_MULAW_8
|
|---|
| 448 | self._framesize = 1
|
|---|
| 449 | else:
|
|---|
| 450 | raise Error, 'internal error'
|
|---|
| 451 | self._framesize = self._framesize * self._nchannels
|
|---|
| 452 | _write_u32(self._file, AUDIO_FILE_MAGIC)
|
|---|
| 453 | header_size = 25 + len(self._info)
|
|---|
| 454 | header_size = (header_size + 7) & ~7
|
|---|
| 455 | _write_u32(self._file, header_size)
|
|---|
| 456 | if self._nframes == AUDIO_UNKNOWN_SIZE:
|
|---|
| 457 | length = AUDIO_UNKNOWN_SIZE
|
|---|
| 458 | else:
|
|---|
| 459 | length = self._nframes * self._framesize
|
|---|
| 460 | try:
|
|---|
| 461 | self._form_length_pos = self._file.tell()
|
|---|
| 462 | except (AttributeError, IOError):
|
|---|
| 463 | self._form_length_pos = None
|
|---|
| 464 | _write_u32(self._file, length)
|
|---|
| 465 | self._datalength = length
|
|---|
| 466 | _write_u32(self._file, encoding)
|
|---|
| 467 | _write_u32(self._file, self._framerate)
|
|---|
| 468 | _write_u32(self._file, self._nchannels)
|
|---|
| 469 | self._file.write(self._info)
|
|---|
| 470 | self._file.write('\0'*(header_size - len(self._info) - 24))
|
|---|
| 471 |
|
|---|
| 472 | def _patchheader(self):
|
|---|
| 473 | if self._form_length_pos is None:
|
|---|
| 474 | raise IOError('cannot seek')
|
|---|
| 475 | self._file.seek(self._form_length_pos)
|
|---|
| 476 | _write_u32(self._file, self._datawritten)
|
|---|
| 477 | self._datalength = self._datawritten
|
|---|
| 478 | self._file.seek(0, 2)
|
|---|
| 479 |
|
|---|
| 480 | def open(f, mode=None):
|
|---|
| 481 | if mode is None:
|
|---|
| 482 | if hasattr(f, 'mode'):
|
|---|
| 483 | mode = f.mode
|
|---|
| 484 | else:
|
|---|
| 485 | mode = 'rb'
|
|---|
| 486 | if mode in ('r', 'rb'):
|
|---|
| 487 | return Au_read(f)
|
|---|
| 488 | elif mode in ('w', 'wb'):
|
|---|
| 489 | return Au_write(f)
|
|---|
| 490 | else:
|
|---|
| 491 | raise Error, "mode must be 'r', 'rb', 'w', or 'wb'"
|
|---|
| 492 |
|
|---|
| 493 | openfp = open
|
|---|
