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920dae64 AT |
1 | """Stuff to parse Sun and NeXT audio files. |
2 | ||
3 | An audio file consists of a header followed by the data. The structure | |
4 | of the header is as follows. | |
5 | ||
6 | +---------------+ | |
7 | | magic word | | |
8 | +---------------+ | |
9 | | header size | | |
10 | +---------------+ | |
11 | | data size | | |
12 | +---------------+ | |
13 | | encoding | | |
14 | +---------------+ | |
15 | | sample rate | | |
16 | +---------------+ | |
17 | | # of channels | | |
18 | +---------------+ | |
19 | | info | | |
20 | | | | |
21 | +---------------+ | |
22 | ||
23 | The magic word consists of the 4 characters '.snd'. Apart from the | |
24 | info field, all header fields are 4 bytes in size. They are all | |
25 | 32-bit unsigned integers encoded in big-endian byte order. | |
26 | ||
27 | The header size really gives the start of the data. | |
28 | The data size is the physical size of the data. From the other | |
29 | parameters the number of frames can be calculated. | |
30 | The encoding gives the way in which audio samples are encoded. | |
31 | Possible values are listed below. | |
32 | The info field currently consists of an ASCII string giving a | |
33 | human-readable description of the audio file. The info field is | |
34 | padded with NUL bytes to the header size. | |
35 | ||
36 | Usage. | |
37 | ||
38 | Reading audio files: | |
39 | f = sunau.open(file, 'r') | |
40 | where file is either the name of a file or an open file pointer. | |
41 | The open file pointer must have methods read(), seek(), and close(). | |
42 | When the setpos() and rewind() methods are not used, the seek() | |
43 | method is not necessary. | |
44 | ||
45 | This returns an instance of a class with the following public methods: | |
46 | getnchannels() -- returns number of audio channels (1 for | |
47 | mono, 2 for stereo) | |
48 | getsampwidth() -- returns sample width in bytes | |
49 | getframerate() -- returns sampling frequency | |
50 | getnframes() -- returns number of audio frames | |
51 | getcomptype() -- returns compression type ('NONE' or 'ULAW') | |
52 | getcompname() -- returns human-readable version of | |
53 | compression type ('not compressed' matches 'NONE') | |
54 | getparams() -- returns a tuple consisting of all of the | |
55 | above in the above order | |
56 | getmarkers() -- returns None (for compatibility with the | |
57 | aifc module) | |
58 | getmark(id) -- raises an error since the mark does not | |
59 | exist (for compatibility with the aifc module) | |
60 | readframes(n) -- returns at most n frames of audio | |
61 | rewind() -- rewind to the beginning of the audio stream | |
62 | setpos(pos) -- seek to the specified position | |
63 | tell() -- return the current position | |
64 | close() -- close the instance (make it unusable) | |
65 | The position returned by tell() and the position given to setpos() | |
66 | are compatible and have nothing to do with the actual position in the | |
67 | file. | |
68 | The close() method is called automatically when the class instance | |
69 | is destroyed. | |
70 | ||
71 | Writing audio files: | |
72 | f = sunau.open(file, 'w') | |
73 | where file is either the name of a file or an open file pointer. | |
74 | The open file pointer must have methods write(), tell(), seek(), and | |
75 | close(). | |
76 | ||
77 | This returns an instance of a class with the following public methods: | |
78 | setnchannels(n) -- set the number of channels | |
79 | setsampwidth(n) -- set the sample width | |
80 | setframerate(n) -- set the frame rate | |
81 | setnframes(n) -- set the number of frames | |
82 | setcomptype(type, name) | |
83 | -- set the compression type and the | |
84 | human-readable compression type | |
85 | setparams(tuple)-- set all parameters at once | |
86 | tell() -- return current position in output file | |
87 | writeframesraw(data) | |
88 | -- write audio frames without pathing up the | |
89 | file header | |
90 | writeframes(data) | |
91 | -- write audio frames and patch up the file header | |
92 | close() -- patch up the file header and close the | |
93 | output file | |
94 | You should set the parameters before the first writeframesraw or | |
95 | writeframes. The total number of frames does not need to be set, | |
96 | but when it is set to the correct value, the header does not have to | |
97 | be patched up. | |
98 | It is best to first set all parameters, perhaps possibly the | |
99 | compression type, and then write audio frames using writeframesraw. | |
100 | When all frames have been written, either call writeframes('') or | |
101 | close() to patch up the sizes in the header. | |
102 | The close() method is called automatically when the class instance | |
103 | is destroyed. | |
104 | """ | |
105 | ||
106 | # from <multimedia/audio_filehdr.h> | |
107 | AUDIO_FILE_MAGIC = 0x2e736e64 | |
108 | AUDIO_FILE_ENCODING_MULAW_8 = 1 | |
109 | AUDIO_FILE_ENCODING_LINEAR_8 = 2 | |
110 | AUDIO_FILE_ENCODING_LINEAR_16 = 3 | |
111 | AUDIO_FILE_ENCODING_LINEAR_24 = 4 | |
112 | AUDIO_FILE_ENCODING_LINEAR_32 = 5 | |
113 | AUDIO_FILE_ENCODING_FLOAT = 6 | |
114 | AUDIO_FILE_ENCODING_DOUBLE = 7 | |
115 | AUDIO_FILE_ENCODING_ADPCM_G721 = 23 | |
116 | AUDIO_FILE_ENCODING_ADPCM_G722 = 24 | |
117 | AUDIO_FILE_ENCODING_ADPCM_G723_3 = 25 | |
118 | AUDIO_FILE_ENCODING_ADPCM_G723_5 = 26 | |
119 | AUDIO_FILE_ENCODING_ALAW_8 = 27 | |
120 | ||
121 | # from <multimedia/audio_hdr.h> | |
122 | AUDIO_UNKNOWN_SIZE = 0xFFFFFFFFL # ((unsigned)(~0)) | |
123 | ||
124 | _simple_encodings = [AUDIO_FILE_ENCODING_MULAW_8, | |
125 | AUDIO_FILE_ENCODING_LINEAR_8, | |
126 | AUDIO_FILE_ENCODING_LINEAR_16, | |
127 | AUDIO_FILE_ENCODING_LINEAR_24, | |
128 | AUDIO_FILE_ENCODING_LINEAR_32, | |
129 | AUDIO_FILE_ENCODING_ALAW_8] | |
130 | ||
131 | class Error(Exception): | |
132 | pass | |
133 | ||
134 | def _read_u32(file): | |
135 | x = 0L | |
136 | for i in range(4): | |
137 | byte = file.read(1) | |
138 | if byte == '': | |
139 | raise EOFError | |
140 | x = x*256 + ord(byte) | |
141 | return x | |
142 | ||
143 | def _write_u32(file, x): | |
144 | data = [] | |
145 | for i in range(4): | |
146 | d, m = divmod(x, 256) | |
147 | data.insert(0, m) | |
148 | x = d | |
149 | for i in range(4): | |
150 | file.write(chr(int(data[i]))) | |
151 | ||
152 | class Au_read: | |
153 | ||
154 | def __init__(self, f): | |
155 | if type(f) == type(''): | |
156 | import __builtin__ | |
157 | f = __builtin__.open(f, 'rb') | |
158 | self.initfp(f) | |
159 | ||
160 | def __del__(self): | |
161 | if self._file: | |
162 | self.close() | |
163 | ||
164 | def initfp(self, file): | |
165 | self._file = file | |
166 | self._soundpos = 0 | |
167 | magic = int(_read_u32(file)) | |
168 | if magic != AUDIO_FILE_MAGIC: | |
169 | raise Error, 'bad magic number' | |
170 | self._hdr_size = int(_read_u32(file)) | |
171 | if self._hdr_size < 24: | |
172 | raise Error, 'header size too small' | |
173 | if self._hdr_size > 100: | |
174 | raise Error, 'header size ridiculously large' | |
175 | self._data_size = _read_u32(file) | |
176 | if self._data_size != AUDIO_UNKNOWN_SIZE: | |
177 | self._data_size = int(self._data_size) | |
178 | self._encoding = int(_read_u32(file)) | |
179 | if self._encoding not in _simple_encodings: | |
180 | raise Error, 'encoding not (yet) supported' | |
181 | if self._encoding in (AUDIO_FILE_ENCODING_MULAW_8, | |
182 | AUDIO_FILE_ENCODING_ALAW_8): | |
183 | self._sampwidth = 2 | |
184 | self._framesize = 1 | |
185 | elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_8: | |
186 | self._framesize = self._sampwidth = 1 | |
187 | elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_16: | |
188 | self._framesize = self._sampwidth = 2 | |
189 | elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_24: | |
190 | self._framesize = self._sampwidth = 3 | |
191 | elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_32: | |
192 | self._framesize = self._sampwidth = 4 | |
193 | else: | |
194 | raise Error, 'unknown encoding' | |
195 | self._framerate = int(_read_u32(file)) | |
196 | self._nchannels = int(_read_u32(file)) | |
197 | self._framesize = self._framesize * self._nchannels | |
198 | if self._hdr_size > 24: | |
199 | self._info = file.read(self._hdr_size - 24) | |
200 | for i in range(len(self._info)): | |
201 | if self._info[i] == '\0': | |
202 | self._info = self._info[:i] | |
203 | break | |
204 | else: | |
205 | self._info = '' | |
206 | ||
207 | def getfp(self): | |
208 | return self._file | |
209 | ||
210 | def getnchannels(self): | |
211 | return self._nchannels | |
212 | ||
213 | def getsampwidth(self): | |
214 | return self._sampwidth | |
215 | ||
216 | def getframerate(self): | |
217 | return self._framerate | |
218 | ||
219 | def getnframes(self): | |
220 | if self._data_size == AUDIO_UNKNOWN_SIZE: | |
221 | return AUDIO_UNKNOWN_SIZE | |
222 | if self._encoding in _simple_encodings: | |
223 | return self._data_size / self._framesize | |
224 | return 0 # XXX--must do some arithmetic here | |
225 | ||
226 | def getcomptype(self): | |
227 | if self._encoding == AUDIO_FILE_ENCODING_MULAW_8: | |
228 | return 'ULAW' | |
229 | elif self._encoding == AUDIO_FILE_ENCODING_ALAW_8: | |
230 | return 'ALAW' | |
231 | else: | |
232 | return 'NONE' | |
233 | ||
234 | def getcompname(self): | |
235 | if self._encoding == AUDIO_FILE_ENCODING_MULAW_8: | |
236 | return 'CCITT G.711 u-law' | |
237 | elif self._encoding == AUDIO_FILE_ENCODING_ALAW_8: | |
238 | return 'CCITT G.711 A-law' | |
239 | else: | |
240 | return 'not compressed' | |
241 | ||
242 | def getparams(self): | |
243 | return self.getnchannels(), self.getsampwidth(), \ | |
244 | self.getframerate(), self.getnframes(), \ | |
245 | self.getcomptype(), self.getcompname() | |
246 | ||
247 | def getmarkers(self): | |
248 | return None | |
249 | ||
250 | def getmark(self, id): | |
251 | raise Error, 'no marks' | |
252 | ||
253 | def readframes(self, nframes): | |
254 | if self._encoding in _simple_encodings: | |
255 | if nframes == AUDIO_UNKNOWN_SIZE: | |
256 | data = self._file.read() | |
257 | else: | |
258 | data = self._file.read(nframes * self._framesize * self._nchannels) | |
259 | if self._encoding == AUDIO_FILE_ENCODING_MULAW_8: | |
260 | import audioop | |
261 | data = audioop.ulaw2lin(data, self._sampwidth) | |
262 | return data | |
263 | return None # XXX--not implemented yet | |
264 | ||
265 | def rewind(self): | |
266 | self._soundpos = 0 | |
267 | self._file.seek(self._hdr_size) | |
268 | ||
269 | def tell(self): | |
270 | return self._soundpos | |
271 | ||
272 | def setpos(self, pos): | |
273 | if pos < 0 or pos > self.getnframes(): | |
274 | raise Error, 'position not in range' | |
275 | self._file.seek(pos * self._framesize + self._hdr_size) | |
276 | self._soundpos = pos | |
277 | ||
278 | def close(self): | |
279 | self._file = None | |
280 | ||
281 | class Au_write: | |
282 | ||
283 | def __init__(self, f): | |
284 | if type(f) == type(''): | |
285 | import __builtin__ | |
286 | f = __builtin__.open(f, 'wb') | |
287 | self.initfp(f) | |
288 | ||
289 | def __del__(self): | |
290 | if self._file: | |
291 | self.close() | |
292 | ||
293 | def initfp(self, file): | |
294 | self._file = file | |
295 | self._framerate = 0 | |
296 | self._nchannels = 0 | |
297 | self._sampwidth = 0 | |
298 | self._framesize = 0 | |
299 | self._nframes = AUDIO_UNKNOWN_SIZE | |
300 | self._nframeswritten = 0 | |
301 | self._datawritten = 0 | |
302 | self._datalength = 0 | |
303 | self._info = '' | |
304 | self._comptype = 'ULAW' # default is U-law | |
305 | ||
306 | def setnchannels(self, nchannels): | |
307 | if self._nframeswritten: | |
308 | raise Error, 'cannot change parameters after starting to write' | |
309 | if nchannels not in (1, 2, 4): | |
310 | raise Error, 'only 1, 2, or 4 channels supported' | |
311 | self._nchannels = nchannels | |
312 | ||
313 | def getnchannels(self): | |
314 | if not self._nchannels: | |
315 | raise Error, 'number of channels not set' | |
316 | return self._nchannels | |
317 | ||
318 | def setsampwidth(self, sampwidth): | |
319 | if self._nframeswritten: | |
320 | raise Error, 'cannot change parameters after starting to write' | |
321 | if sampwidth not in (1, 2, 4): | |
322 | raise Error, 'bad sample width' | |
323 | self._sampwidth = sampwidth | |
324 | ||
325 | def getsampwidth(self): | |
326 | if not self._framerate: | |
327 | raise Error, 'sample width not specified' | |
328 | return self._sampwidth | |
329 | ||
330 | def setframerate(self, framerate): | |
331 | if self._nframeswritten: | |
332 | raise Error, 'cannot change parameters after starting to write' | |
333 | self._framerate = framerate | |
334 | ||
335 | def getframerate(self): | |
336 | if not self._framerate: | |
337 | raise Error, 'frame rate not set' | |
338 | return self._framerate | |
339 | ||
340 | def setnframes(self, nframes): | |
341 | if self._nframeswritten: | |
342 | raise Error, 'cannot change parameters after starting to write' | |
343 | if nframes < 0: | |
344 | raise Error, '# of frames cannot be negative' | |
345 | self._nframes = nframes | |
346 | ||
347 | def getnframes(self): | |
348 | return self._nframeswritten | |
349 | ||
350 | def setcomptype(self, type, name): | |
351 | if type in ('NONE', 'ULAW'): | |
352 | self._comptype = type | |
353 | else: | |
354 | raise Error, 'unknown compression type' | |
355 | ||
356 | def getcomptype(self): | |
357 | return self._comptype | |
358 | ||
359 | def getcompname(self): | |
360 | if self._comptype == 'ULAW': | |
361 | return 'CCITT G.711 u-law' | |
362 | elif self._comptype == 'ALAW': | |
363 | return 'CCITT G.711 A-law' | |
364 | else: | |
365 | return 'not compressed' | |
366 | ||
367 | def setparams(self, (nchannels, sampwidth, framerate, nframes, comptype, compname)): | |
368 | self.setnchannels(nchannels) | |
369 | self.setsampwidth(sampwidth) | |
370 | self.setframerate(framerate) | |
371 | self.setnframes(nframes) | |
372 | self.setcomptype(comptype, compname) | |
373 | ||
374 | def getparams(self): | |
375 | return self.getnchannels(), self.getsampwidth(), \ | |
376 | self.getframerate(), self.getnframes(), \ | |
377 | self.getcomptype(), self.getcompname() | |
378 | ||
379 | def tell(self): | |
380 | return self._nframeswritten | |
381 | ||
382 | def writeframesraw(self, data): | |
383 | self._ensure_header_written() | |
384 | nframes = len(data) / self._framesize | |
385 | if self._comptype == 'ULAW': | |
386 | import audioop | |
387 | data = audioop.lin2ulaw(data, self._sampwidth) | |
388 | self._file.write(data) | |
389 | self._nframeswritten = self._nframeswritten + nframes | |
390 | self._datawritten = self._datawritten + len(data) | |
391 | ||
392 | def writeframes(self, data): | |
393 | self.writeframesraw(data) | |
394 | if self._nframeswritten != self._nframes or \ | |
395 | self._datalength != self._datawritten: | |
396 | self._patchheader() | |
397 | ||
398 | def close(self): | |
399 | self._ensure_header_written() | |
400 | if self._nframeswritten != self._nframes or \ | |
401 | self._datalength != self._datawritten: | |
402 | self._patchheader() | |
403 | self._file.flush() | |
404 | self._file = None | |
405 | ||
406 | # | |
407 | # private methods | |
408 | # | |
409 | ||
410 | def _ensure_header_written(self): | |
411 | if not self._nframeswritten: | |
412 | if not self._nchannels: | |
413 | raise Error, '# of channels not specified' | |
414 | if not self._sampwidth: | |
415 | raise Error, 'sample width not specified' | |
416 | if not self._framerate: | |
417 | raise Error, 'frame rate not specified' | |
418 | self._write_header() | |
419 | ||
420 | def _write_header(self): | |
421 | if self._comptype == 'NONE': | |
422 | if self._sampwidth == 1: | |
423 | encoding = AUDIO_FILE_ENCODING_LINEAR_8 | |
424 | self._framesize = 1 | |
425 | elif self._sampwidth == 2: | |
426 | encoding = AUDIO_FILE_ENCODING_LINEAR_16 | |
427 | self._framesize = 2 | |
428 | elif self._sampwidth == 4: | |
429 | encoding = AUDIO_FILE_ENCODING_LINEAR_32 | |
430 | self._framesize = 4 | |
431 | else: | |
432 | raise Error, 'internal error' | |
433 | elif self._comptype == 'ULAW': | |
434 | encoding = AUDIO_FILE_ENCODING_MULAW_8 | |
435 | self._framesize = 1 | |
436 | else: | |
437 | raise Error, 'internal error' | |
438 | self._framesize = self._framesize * self._nchannels | |
439 | _write_u32(self._file, AUDIO_FILE_MAGIC) | |
440 | header_size = 25 + len(self._info) | |
441 | header_size = (header_size + 7) & ~7 | |
442 | _write_u32(self._file, header_size) | |
443 | if self._nframes == AUDIO_UNKNOWN_SIZE: | |
444 | length = AUDIO_UNKNOWN_SIZE | |
445 | else: | |
446 | length = self._nframes * self._framesize | |
447 | _write_u32(self._file, length) | |
448 | self._datalength = length | |
449 | _write_u32(self._file, encoding) | |
450 | _write_u32(self._file, self._framerate) | |
451 | _write_u32(self._file, self._nchannels) | |
452 | self._file.write(self._info) | |
453 | self._file.write('\0'*(header_size - len(self._info) - 24)) | |
454 | ||
455 | def _patchheader(self): | |
456 | self._file.seek(8) | |
457 | _write_u32(self._file, self._datawritten) | |
458 | self._datalength = self._datawritten | |
459 | self._file.seek(0, 2) | |
460 | ||
461 | def open(f, mode=None): | |
462 | if mode is None: | |
463 | if hasattr(f, 'mode'): | |
464 | mode = f.mode | |
465 | else: | |
466 | mode = 'rb' | |
467 | if mode in ('r', 'rb'): | |
468 | return Au_read(f) | |
469 | elif mode in ('w', 'wb'): | |
470 | return Au_write(f) | |
471 | else: | |
472 | raise Error, "mode must be 'r', 'rb', 'w', or 'wb'" | |
473 | ||
474 | openfp = open |