rate: add some sanity checking
[sox.git] / src / sndfile.c
blob1eda79c7c1ab190d35e5676f73c71d8427b0d531
1 /* libSoX libsndfile formats.
3 * Copyright 2007 Reuben Thomas <rrt@sc3d.org>
4 * Copyright 1999-2005 Erik de Castro Lopo <eridk@mega-nerd.com>
6 * This library is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU Lesser General Public License as published by
8 * the Free Software Foundation; either version 2.1 of the License, or (at
9 * your option) any later version.
11 * This library is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
14 * General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public License
17 * along with this library; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 #include "sox_i.h"
23 #include <assert.h>
24 #include <stdio.h>
25 #include <string.h>
26 #include <ctype.h>
27 #include <sndfile.h>
29 #define LOG_MAX 2048 /* As per the SFC_GET_LOG_INFO example */
31 static const char* const sndfile_library_names[] =
33 #ifdef DL_LIBSNDFILE
34 "libsndfile",
35 "libsndfile-1",
36 "cygsndfile-1",
37 #endif
38 NULL
41 #ifdef DL_LIBSNDFILE
42 #define SNDFILE_FUNC LSX_DLENTRY_DYNAMIC
43 #define SNDFILE_FUNC_STOP LSX_DLENTRY_STUB
44 #else
45 #define SNDFILE_FUNC LSX_DLENTRY_STATIC
46 #ifdef HACKED_LSF
47 #define SNDFILE_FUNC_STOP LSX_DLENTRY_STATIC
48 #else
49 #define SNDFILE_FUNC_STOP LSX_DLENTRY_STUB
50 #endif
51 #endif /* DL_LIBSNDFILE */
53 #define SNDFILE_FUNC_OPEN(f,x) \
54 SNDFILE_FUNC(f,x, SNDFILE*, sf_open_virtual, (SF_VIRTUAL_IO *sfvirtual, int mode, SF_INFO *sfinfo, void *user_data))
56 #define SNDFILE_FUNC_ENTRIES(f,x) \
57 SNDFILE_FUNC_OPEN(f,x) \
58 SNDFILE_FUNC_STOP(f,x, int, sf_stop, (SNDFILE *sndfile)) \
59 SNDFILE_FUNC(f,x, int, sf_close, (SNDFILE *sndfile)) \
60 SNDFILE_FUNC(f,x, int, sf_format_check, (const SF_INFO *info)) \
61 SNDFILE_FUNC(f,x, int, sf_command, (SNDFILE *sndfile, int command, void *data, int datasize)) \
62 SNDFILE_FUNC(f,x, sf_count_t, sf_read_int, (SNDFILE *sndfile, int *ptr, sf_count_t items)) \
63 SNDFILE_FUNC(f,x, sf_count_t, sf_write_int, (SNDFILE *sndfile, const int *ptr, sf_count_t items)) \
64 SNDFILE_FUNC(f,x, sf_count_t, sf_seek, (SNDFILE *sndfile, sf_count_t frames, int whence)) \
65 SNDFILE_FUNC(f,x, const char*, sf_strerror, (SNDFILE *sndfile))
67 /* Private data for sndfile files */
68 typedef struct {
69 SNDFILE *sf_file;
70 SF_INFO *sf_info;
71 char * log_buffer;
72 char const * log_buffer_ptr;
73 LSX_DLENTRIES_TO_PTRS(SNDFILE_FUNC_ENTRIES, sndfile_dl);
74 } priv_t;
77 * Drain LSF's wonderful log buffer
79 static void drain_log_buffer(sox_format_t * ft)
81 priv_t * sf = (priv_t *)ft->priv;
82 sf->sf_command(sf->sf_file, SFC_GET_LOG_INFO, sf->log_buffer, LOG_MAX);
83 while (*sf->log_buffer_ptr) {
84 static char const warning_prefix[] = "*** Warning : ";
85 char const * end = strchr(sf->log_buffer_ptr, '\n');
86 if (!end)
87 end = strchr(sf->log_buffer_ptr, '\0');
88 if (!strncmp(sf->log_buffer_ptr, warning_prefix, strlen(warning_prefix))) {
89 sf->log_buffer_ptr += strlen(warning_prefix);
90 lsx_warn("`%s': %.*s",
91 ft->filename, (int)(end - sf->log_buffer_ptr), sf->log_buffer_ptr);
92 } else
93 lsx_debug("`%s': %.*s",
94 ft->filename, (int)(end - sf->log_buffer_ptr), sf->log_buffer_ptr);
95 sf->log_buffer_ptr = end;
96 if (*sf->log_buffer_ptr == '\n')
97 ++sf->log_buffer_ptr;
101 /* Make libsndfile subtype from sample encoding and size */
102 static int ft_enc(unsigned size, sox_encoding_t e)
104 if (e == SOX_ENCODING_ULAW && size == 8) return SF_FORMAT_ULAW;
105 if (e == SOX_ENCODING_ALAW && size == 8) return SF_FORMAT_ALAW;
106 if (e == SOX_ENCODING_SIGN2 && size == 8) return SF_FORMAT_PCM_S8;
107 if (e == SOX_ENCODING_SIGN2 && size == 16) return SF_FORMAT_PCM_16;
108 if (e == SOX_ENCODING_SIGN2 && size == 24) return SF_FORMAT_PCM_24;
109 if (e == SOX_ENCODING_SIGN2 && size == 32) return SF_FORMAT_PCM_32;
110 if (e == SOX_ENCODING_UNSIGNED && size == 8) return SF_FORMAT_PCM_U8;
111 if (e == SOX_ENCODING_FLOAT && size == 32) return SF_FORMAT_FLOAT;
112 if (e == SOX_ENCODING_FLOAT && size == 64) return SF_FORMAT_DOUBLE;
113 if (e == SOX_ENCODING_G721 && size == 4) return SF_FORMAT_G721_32;
114 if (e == SOX_ENCODING_G723 && size == 3) return SF_FORMAT_G723_24;
115 if (e == SOX_ENCODING_G723 && size == 5) return SF_FORMAT_G723_40;
116 if (e == SOX_ENCODING_MS_ADPCM && size == 4) return SF_FORMAT_MS_ADPCM;
117 if (e == SOX_ENCODING_IMA_ADPCM && size == 4) return SF_FORMAT_IMA_ADPCM;
118 if (e == SOX_ENCODING_OKI_ADPCM && size == 4) return SF_FORMAT_VOX_ADPCM;
119 if (e == SOX_ENCODING_DPCM && size == 8) return SF_FORMAT_DPCM_8;
120 if (e == SOX_ENCODING_DPCM && size == 16) return SF_FORMAT_DPCM_16;
121 if (e == SOX_ENCODING_DWVW && size == 12) return SF_FORMAT_DWVW_12;
122 if (e == SOX_ENCODING_DWVW && size == 16) return SF_FORMAT_DWVW_16;
123 if (e == SOX_ENCODING_DWVW && size == 24) return SF_FORMAT_DWVW_24;
124 if (e == SOX_ENCODING_DWVWN && size == 0) return SF_FORMAT_DWVW_N;
125 if (e == SOX_ENCODING_GSM && size == 0) return SF_FORMAT_GSM610;
126 if (e == SOX_ENCODING_FLAC && size == 8) return SF_FORMAT_PCM_S8;
127 if (e == SOX_ENCODING_FLAC && size == 16) return SF_FORMAT_PCM_16;
128 if (e == SOX_ENCODING_FLAC && size == 24) return SF_FORMAT_PCM_24;
129 if (e == SOX_ENCODING_FLAC && size == 32) return SF_FORMAT_PCM_32;
130 return 0; /* Bad encoding */
133 /* Convert format's encoding type to libSoX encoding type & size. */
134 static sox_encoding_t sox_enc(int ft_encoding, unsigned * size)
136 int sub = ft_encoding & SF_FORMAT_SUBMASK;
137 int type = ft_encoding & SF_FORMAT_TYPEMASK;
139 if (type == SF_FORMAT_FLAC) switch (sub) {
140 case SF_FORMAT_PCM_S8 : *size = 8; return SOX_ENCODING_FLAC;
141 case SF_FORMAT_PCM_16 : *size = 16; return SOX_ENCODING_FLAC;
142 case SF_FORMAT_PCM_24 : *size = 24; return SOX_ENCODING_FLAC;
144 switch (sub) {
145 case SF_FORMAT_ULAW : *size = 8; return SOX_ENCODING_ULAW;
146 case SF_FORMAT_ALAW : *size = 8; return SOX_ENCODING_ALAW;
147 case SF_FORMAT_PCM_S8 : *size = 8; return SOX_ENCODING_SIGN2;
148 case SF_FORMAT_PCM_16 : *size = 16; return SOX_ENCODING_SIGN2;
149 case SF_FORMAT_PCM_24 : *size = 24; return SOX_ENCODING_SIGN2;
150 case SF_FORMAT_PCM_32 : *size = 32; return SOX_ENCODING_SIGN2;
151 case SF_FORMAT_PCM_U8 : *size = 8; return SOX_ENCODING_UNSIGNED;
152 case SF_FORMAT_FLOAT : *size = 32; return SOX_ENCODING_FLOAT;
153 case SF_FORMAT_DOUBLE : *size = 64; return SOX_ENCODING_FLOAT;
154 case SF_FORMAT_G721_32 : *size = 4; return SOX_ENCODING_G721;
155 case SF_FORMAT_G723_24 : *size = 3; return SOX_ENCODING_G723;
156 case SF_FORMAT_G723_40 : *size = 5; return SOX_ENCODING_G723;
157 case SF_FORMAT_MS_ADPCM : *size = 4; return SOX_ENCODING_MS_ADPCM;
158 case SF_FORMAT_IMA_ADPCM: *size = 4; return SOX_ENCODING_IMA_ADPCM;
159 case SF_FORMAT_VOX_ADPCM: *size = 4; return SOX_ENCODING_OKI_ADPCM;
160 case SF_FORMAT_DPCM_8 : *size = 8; return SOX_ENCODING_DPCM;
161 case SF_FORMAT_DPCM_16 : *size = 16; return SOX_ENCODING_DPCM;
162 case SF_FORMAT_DWVW_12 : *size = 12; return SOX_ENCODING_DWVW;
163 case SF_FORMAT_DWVW_16 : *size = 16; return SOX_ENCODING_DWVW;
164 case SF_FORMAT_DWVW_24 : *size = 24; return SOX_ENCODING_DWVW;
165 case SF_FORMAT_DWVW_N : *size = 0; return SOX_ENCODING_DWVWN;
166 case SF_FORMAT_GSM610 : *size = 0; return SOX_ENCODING_GSM;
167 default : *size = 0; return SOX_ENCODING_UNKNOWN;
171 static struct {
172 const char *ext;
173 int format;
174 } format_map[] =
176 { "aif", SF_FORMAT_AIFF },
177 { "aiff", SF_FORMAT_AIFF },
178 { "wav", SF_FORMAT_WAV },
179 { "au", SF_FORMAT_AU },
180 { "snd", SF_FORMAT_AU },
181 { "caf", SF_FORMAT_CAF },
182 { "flac", SF_FORMAT_FLAC },
183 { "wve", SF_FORMAT_WVE },
184 { "ogg", SF_FORMAT_OGG },
185 { "svx", SF_FORMAT_SVX },
186 { "8svx", SF_FORMAT_SVX },
187 { "paf", SF_ENDIAN_BIG | SF_FORMAT_PAF },
188 { "fap", SF_ENDIAN_LITTLE | SF_FORMAT_PAF },
189 { "gsm", SF_FORMAT_RAW | SF_FORMAT_GSM610 },
190 { "nist", SF_FORMAT_NIST },
191 { "sph", SF_FORMAT_NIST },
192 { "ircam", SF_FORMAT_IRCAM },
193 { "sf", SF_FORMAT_IRCAM },
194 { "voc", SF_FORMAT_VOC },
195 { "w64", SF_FORMAT_W64 },
196 { "raw", SF_FORMAT_RAW },
197 { "mat4", SF_FORMAT_MAT4 },
198 { "mat5", SF_FORMAT_MAT5 },
199 { "mat", SF_FORMAT_MAT4 },
200 { "pvf", SF_FORMAT_PVF },
201 { "sds", SF_FORMAT_SDS },
202 { "sd2", SF_FORMAT_SD2 },
203 { "vox", SF_FORMAT_RAW | SF_FORMAT_VOX_ADPCM },
204 { "xi", SF_FORMAT_XI }
207 static int sf_stop_stub(SNDFILE *sndfile UNUSED)
209 return 1;
212 static sf_count_t vio_get_filelen(void *user_data)
214 sox_format_t *ft = (sox_format_t *)user_data;
216 /* lsf excepts unbuffered I/O behavior for get_filelen() so force that */
217 lsx_flush(ft);
219 return (sf_count_t)lsx_filelength((sox_format_t *)user_data);
222 static sf_count_t vio_seek(sf_count_t offset, int whence, void *user_data)
224 return lsx_seeki((sox_format_t *)user_data, (off_t)offset, whence);
227 static sf_count_t vio_read(void *ptr, sf_count_t count, void *user_data)
229 return lsx_readbuf((sox_format_t *)user_data, ptr, (size_t)count);
232 static sf_count_t vio_write(const void *ptr, sf_count_t count, void *user_data)
234 return lsx_writebuf((sox_format_t *)user_data, ptr, (size_t)count);
237 static sf_count_t vio_tell(void *user_data)
239 return lsx_tell((sox_format_t *)user_data);
242 static SF_VIRTUAL_IO vio =
244 vio_get_filelen,
245 vio_seek,
246 vio_read,
247 vio_write,
248 vio_tell
251 /* Convert file name or type to libsndfile format */
252 static int name_to_format(const char *name)
254 int k;
255 #define FILE_TYPE_BUFLEN (size_t)15
256 char buffer[FILE_TYPE_BUFLEN + 1], *cptr;
258 if ((cptr = strrchr(name, '.')) != NULL) {
259 strncpy(buffer, cptr + 1, FILE_TYPE_BUFLEN);
260 buffer[FILE_TYPE_BUFLEN] = '\0';
262 for (k = 0; buffer[k]; k++)
263 buffer[k] = tolower((buffer[k]));
264 } else {
265 strncpy(buffer, name, FILE_TYPE_BUFLEN);
266 buffer[FILE_TYPE_BUFLEN] = '\0';
269 for (k = 0; k < (int)(sizeof(format_map) / sizeof(format_map [0])); k++) {
270 if (strcmp(buffer, format_map[k].ext) == 0)
271 return format_map[k].format;
274 return 0;
277 static int start(sox_format_t * ft)
279 priv_t * sf = (priv_t *)ft->priv;
280 int subtype = ft_enc(ft->encoding.bits_per_sample? ft->encoding.bits_per_sample : ft->signal.precision, ft->encoding.encoding);
281 int open_library_result;
283 LSX_DLLIBRARY_OPEN(
285 sndfile_dl,
286 SNDFILE_FUNC_ENTRIES,
287 "libsndfile library",
288 sndfile_library_names,
289 open_library_result);
290 if (open_library_result)
291 return SOX_EOF;
293 sf->log_buffer_ptr = sf->log_buffer = lsx_malloc((size_t)LOG_MAX);
294 sf->sf_info = lsx_calloc(1, sizeof(SF_INFO));
296 /* Copy format info */
297 if (subtype) {
298 if (strcmp(ft->filetype, "sndfile") == 0)
299 sf->sf_info->format = name_to_format(ft->filename) | subtype;
300 else
301 sf->sf_info->format = name_to_format(ft->filetype) | subtype;
303 sf->sf_info->samplerate = (int)ft->signal.rate;
304 sf->sf_info->channels = ft->signal.channels;
305 if (ft->signal.channels)
306 sf->sf_info->frames = ft->signal.length / ft->signal.channels;
308 return SOX_SUCCESS;
311 static int check_read_params(sox_format_t * ft, unsigned channels,
312 sox_rate_t rate, sox_encoding_t encoding, unsigned bits_per_sample, uint64_t length)
314 ft->signal.length = length;
316 if (channels && ft->signal.channels && ft->signal.channels != channels)
317 lsx_warn("`%s': overriding number of channels", ft->filename);
318 else ft->signal.channels = channels;
320 if (rate && ft->signal.rate && ft->signal.rate != rate)
321 lsx_warn("`%s': overriding sample rate", ft->filename);
322 else ft->signal.rate = rate;
324 if (encoding && ft->encoding.encoding && ft->encoding.encoding != encoding)
325 lsx_warn("`%s': overriding encoding type", ft->filename);
326 else ft->encoding.encoding = encoding;
328 if (bits_per_sample && ft->encoding.bits_per_sample && ft->encoding.bits_per_sample != bits_per_sample)
329 lsx_warn("`%s': overriding encoding size", ft->filename);
330 ft->encoding.bits_per_sample = bits_per_sample;
332 if (sox_precision(ft->encoding.encoding, ft->encoding.bits_per_sample))
333 return SOX_SUCCESS;
334 lsx_fail_errno(ft, EINVAL, "invalid format for this file type");
335 return SOX_EOF;
339 * Open file in sndfile.
341 static int startread(sox_format_t * ft)
343 priv_t * sf = (priv_t *)ft->priv;
344 unsigned bits_per_sample;
345 sox_encoding_t encoding;
346 sox_rate_t rate;
348 if (start(ft) == SOX_EOF)
349 return SOX_EOF;
351 sf->sf_file = sf->sf_open_virtual(&vio, SFM_READ, sf->sf_info, ft);
352 drain_log_buffer(ft);
354 if (sf->sf_file == NULL) {
355 memset(ft->sox_errstr, 0, sizeof(ft->sox_errstr));
356 strncpy(ft->sox_errstr, sf->sf_strerror(sf->sf_file), sizeof(ft->sox_errstr)-1);
357 free(sf->sf_file);
358 return SOX_EOF;
361 if (!(encoding = sox_enc(sf->sf_info->format, &bits_per_sample))) {
362 lsx_fail_errno(ft, SOX_EFMT, "unsupported sndfile encoding %#x", sf->sf_info->format);
363 return SOX_EOF;
366 /* Don't believe LSF's rate for raw files */
367 if ((sf->sf_info->format & SF_FORMAT_TYPEMASK) == SF_FORMAT_RAW && !ft->signal.rate) {
368 lsx_warn("`%s': sample rate not specified; trying 8kHz", ft->filename);
369 rate = 8000;
371 else rate = sf->sf_info->samplerate;
373 if ((sf->sf_info->format & SF_FORMAT_SUBMASK) == SF_FORMAT_FLOAT) {
374 sf->sf_command(sf->sf_file, SFC_SET_SCALE_FLOAT_INT_READ, NULL, SF_TRUE);
375 sf->sf_command(sf->sf_file, SFC_SET_CLIPPING, NULL, SF_TRUE);
378 #if 0 /* FIXME */
379 sox_append_comments(&ft->oob.comments, buf);
380 #endif
382 return check_read_params(ft, (unsigned)sf->sf_info->channels, rate,
383 encoding, bits_per_sample, (uint64_t)(sf->sf_info->frames * sf->sf_info->channels));
387 * Read up to len samples of type sox_sample_t from file into buf[].
388 * Return number of samples read.
390 static size_t read_samples(sox_format_t * ft, sox_sample_t *buf, size_t len)
392 priv_t * sf = (priv_t *)ft->priv;
393 /* FIXME: We assume int == sox_sample_t here */
394 return (size_t)sf->sf_read_int(sf->sf_file, (int *)buf, (sf_count_t)len);
398 * Close file for libsndfile (this doesn't close the file handle)
400 static int stopread(sox_format_t * ft)
402 priv_t * sf = (priv_t *)ft->priv;
403 sf->sf_stop(sf->sf_file);
404 drain_log_buffer(ft);
405 sf->sf_close(sf->sf_file);
406 LSX_DLLIBRARY_CLOSE(sf, sndfile_dl);
407 return SOX_SUCCESS;
410 static int startwrite(sox_format_t * ft)
412 priv_t * sf = (priv_t *)ft->priv;
414 if (start(ft) == SOX_EOF)
415 return SOX_EOF;
417 /* If output format is invalid, try to find a sensible default */
418 if (!sf->sf_format_check(sf->sf_info)) {
419 SF_FORMAT_INFO format_info;
420 int i, count;
422 sf->sf_command(sf->sf_file, SFC_GET_SIMPLE_FORMAT_COUNT, &count, (int) sizeof(int));
423 for (i = 0; i < count; i++) {
424 format_info.format = i;
425 sf->sf_command(sf->sf_file, SFC_GET_SIMPLE_FORMAT, &format_info, (int) sizeof(format_info));
426 if ((format_info.format & SF_FORMAT_TYPEMASK) == (sf->sf_info->format & SF_FORMAT_TYPEMASK)) {
427 sf->sf_info->format = format_info.format;
428 /* FIXME: Print out exactly what we chose, needs sndfile ->
429 sox encoding conversion functions */
430 break;
434 if (!sf->sf_format_check(sf->sf_info)) {
435 lsx_fail("cannot find a usable output encoding");
436 return SOX_EOF;
438 if ((sf->sf_info->format & SF_FORMAT_TYPEMASK) != SF_FORMAT_RAW)
439 lsx_warn("cannot use desired output encoding, choosing default");
442 sf->sf_file = sf->sf_open_virtual(&vio, SFM_WRITE, sf->sf_info, ft);
443 drain_log_buffer(ft);
445 if (sf->sf_file == NULL) {
446 memset(ft->sox_errstr, 0, sizeof(ft->sox_errstr));
447 strncpy(ft->sox_errstr, sf->sf_strerror(sf->sf_file), sizeof(ft->sox_errstr)-1);
448 free(sf->sf_file);
449 return SOX_EOF;
452 if ((sf->sf_info->format & SF_FORMAT_SUBMASK) == SF_FORMAT_FLOAT)
453 sf->sf_command(sf->sf_file, SFC_SET_SCALE_INT_FLOAT_WRITE, NULL, SF_TRUE);
455 return SOX_SUCCESS;
459 * Write len samples of type sox_sample_t from buf[] to file.
460 * Return number of samples written.
462 static size_t write_samples(sox_format_t * ft, const sox_sample_t *buf, size_t len)
464 priv_t * sf = (priv_t *)ft->priv;
465 /* FIXME: We assume int == sox_sample_t here */
466 return (size_t)sf->sf_write_int(sf->sf_file, (int *)buf, (sf_count_t)len);
470 * Close file for libsndfile (this doesn't close the file handle)
472 static int stopwrite(sox_format_t * ft)
474 priv_t * sf = (priv_t *)ft->priv;
475 sf->sf_stop(sf->sf_file);
476 drain_log_buffer(ft);
477 sf->sf_close(sf->sf_file);
478 LSX_DLLIBRARY_CLOSE(sf, sndfile_dl);
479 return SOX_SUCCESS;
482 static int seek(sox_format_t * ft, uint64_t offset)
484 priv_t * sf = (priv_t *)ft->priv;
485 sf->sf_seek(sf->sf_file, (sf_count_t)(offset / ft->signal.channels), SEEK_CUR);
486 return SOX_SUCCESS;
489 LSX_FORMAT_HANDLER(sndfile)
491 static char const * const names[] = {
492 "sndfile", /* Special type to force use of sndfile for the following: */
493 /* LSF implementation of formats built in to SoX: */
494 /* "aif", */
495 /* "au", */
496 /* "gsm", */
497 /* "nist", */
498 /* "raw", */
499 /* "sf", "ircam", */
500 /* "snd", */
501 /* "svx", */
502 /* "voc", */
503 /* "vox", */
504 /* "wav", */
505 /* LSF wrappers of formats already wrapped in SoX: */
506 /* "flac", */
508 "sds", /* ?? */
509 NULL
512 static unsigned const write_encodings[] = {
513 SOX_ENCODING_SIGN2, 16, 24, 32, 8, 0,
514 SOX_ENCODING_UNSIGNED, 8, 0,
515 SOX_ENCODING_FLOAT, 32, 64, 0,
516 SOX_ENCODING_ALAW, 8, 0,
517 SOX_ENCODING_ULAW, 8, 0,
518 SOX_ENCODING_IMA_ADPCM, 4, 0,
519 SOX_ENCODING_MS_ADPCM, 4, 0,
520 SOX_ENCODING_OKI_ADPCM, 4, 0,
521 SOX_ENCODING_GSM, 0,
524 static sox_format_handler_t const format = {SOX_LIB_VERSION_CODE,
525 "Pseudo format to use libsndfile", names, 0,
526 startread, read_samples, stopread,
527 startwrite, write_samples, stopwrite,
528 seek, write_encodings, NULL, sizeof(priv_t)
531 return &format;