1 /* GStreamer AC3 parser
2 * Copyright (C) 2009 Tim-Philipp Müller <tim centricular net>
3 * Copyright (C) 2009 Mark Nauwelaerts <mnauw users sf net>
4 * Copyright (C) 2009 Nokia Corporation. All rights reserved.
5 * Contact: Stefan Kost <stefan.kost@nokia.com>
6 *
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
11 *
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Library General Public License for more details.
16 *
17 * You should have received a copy of the GNU Library General Public
18 * License along with this library; if not, write to the
19 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
20 * Boston, MA 02110-1301, USA.
21 */
22 /**
23 * SECTION:element-ac3parse
24 * @short_description: AC3 parser
25 * @see_also: #GstAmrParse, #GstAACParse
26 *
27 * This is an AC3 parser.
28 *
29 * <refsect2>
30 * <title>Example launch line</title>
31 * |[
32 * gst-launch-1.0 filesrc location=abc.ac3 ! ac3parse ! a52dec ! audioresample ! audioconvert ! autoaudiosink
33 * ]|
34 * </refsect2>
35 */
36
37 /* TODO:
38 * - audio/ac3 to audio/x-private1-ac3 is not implemented (done in the muxer)
39 * - should accept framed and unframed input (needs decodebin fixes first)
40 */
41
42 #ifdef HAVE_CONFIG_H
43 #include "config.h"
44 #endif
45
46 #include <string.h>
47
48 #include "gstac3parse.h"
49 #include <gst/base/base.h>
50 #include <gst/pbutils/pbutils.h>
51
52 GST_DEBUG_CATEGORY_STATIC (ac3_parse_debug);
53 #define GST_CAT_DEFAULT ac3_parse_debug
54
55 static const struct
56 {
57 const guint bit_rate; /* nominal bit rate */
58 const guint frame_size[3]; /* frame size for 32kHz, 44kHz, and 48kHz */
59 } frmsizcod_table[38] = {
60 {
61 32, {
62 64, 69, 96}}, {
63 32, {
64 64, 70, 96}}, {
65 40, {
66 80, 87, 120}}, {
67 40, {
68 80, 88, 120}}, {
69 48, {
70 96, 104, 144}}, {
71 48, {
72 96, 105, 144}}, {
73 56, {
74 112, 121, 168}}, {
75 56, {
76 112, 122, 168}}, {
77 64, {
78 128, 139, 192}}, {
79 64, {
80 128, 140, 192}}, {
81 80, {
82 160, 174, 240}}, {
83 80, {
84 160, 175, 240}}, {
85 96, {
86 192, 208, 288}}, {
87 96, {
88 192, 209, 288}}, {
89 112, {
90 224, 243, 336}}, {
91 112, {
92 224, 244, 336}}, {
93 128, {
94 256, 278, 384}}, {
95 128, {
96 256, 279, 384}}, {
97 160, {
98 320, 348, 480}}, {
99 160, {
100 320, 349, 480}}, {
101 192, {
102 384, 417, 576}}, {
103 192, {
104 384, 418, 576}}, {
105 224, {
106 448, 487, 672}}, {
107 224, {
108 448, 488, 672}}, {
109 256, {
110 512, 557, 768}}, {
111 256, {
112 512, 558, 768}}, {
113 320, {
114 640, 696, 960}}, {
115 320, {
116 640, 697, 960}}, {
117 384, {
118 768, 835, 1152}}, {
119 384, {
120 768, 836, 1152}}, {
121 448, {
122 896, 975, 1344}}, {
123 448, {
124 896, 976, 1344}}, {
125 512, {
126 1024, 1114, 1536}}, {
127 512, {
128 1024, 1115, 1536}}, {
129 576, {
130 1152, 1253, 1728}}, {
131 576, {
132 1152, 1254, 1728}}, {
133 640, {
134 1280, 1393, 1920}}, {
135 640, {
136 1280, 1394, 1920}}
137 };
138
139 static const guint fscod_rates[4] = { 48000, 44100, 32000, 0 };
140 static const guint acmod_chans[8] = { 2, 1, 2, 3, 3, 4, 4, 5 };
141 static const guint numblks[4] = { 1, 2, 3, 6 };
142
143 static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
144 GST_PAD_SRC,
145 GST_PAD_ALWAYS,
146 GST_STATIC_CAPS ("audio/x-ac3, framed = (boolean) true, "
147 " channels = (int) [ 1, 6 ], rate = (int) [ 8000, 48000 ], "
148 " alignment = (string) { iec61937, frame}; "
149 "audio/x-eac3, framed = (boolean) true, "
150 " channels = (int) [ 1, 6 ], rate = (int) [ 8000, 48000 ], "
151 " alignment = (string) { iec61937, frame}; "));
152
153 static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
154 GST_PAD_SINK,
155 GST_PAD_ALWAYS,
156 GST_STATIC_CAPS ("audio/x-ac3; " "audio/x-eac3; " "audio/ac3; "
157 "audio/x-private1-ac3"));
158
159 static void gst_ac3_parse_finalize (GObject * object);
160
161 static gboolean gst_ac3_parse_start (GstBaseParse * parse);
162 static gboolean gst_ac3_parse_stop (GstBaseParse * parse);
163 static GstFlowReturn gst_ac3_parse_handle_frame (GstBaseParse * parse,
164 GstBaseParseFrame * frame, gint * skipsize);
165 static GstFlowReturn gst_ac3_parse_pre_push_frame (GstBaseParse * parse,
166 GstBaseParseFrame * frame);
167 static gboolean gst_ac3_parse_src_event (GstBaseParse * parse,
168 GstEvent * event);
169 static GstCaps *gst_ac3_parse_get_sink_caps (GstBaseParse * parse,
170 GstCaps * filter);
171 static gboolean gst_ac3_parse_set_sink_caps (GstBaseParse * parse,
172 GstCaps * caps);
173
174 #define gst_ac3_parse_parent_class parent_class
175 G_DEFINE_TYPE (GstAc3Parse, gst_ac3_parse, GST_TYPE_BASE_PARSE);
176
177 static void
gst_ac3_parse_class_init(GstAc3ParseClass * klass)178 gst_ac3_parse_class_init (GstAc3ParseClass * klass)
179 {
180 GObjectClass *object_class = G_OBJECT_CLASS (klass);
181 GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
182 GstBaseParseClass *parse_class = GST_BASE_PARSE_CLASS (klass);
183
184 GST_DEBUG_CATEGORY_INIT (ac3_parse_debug, "ac3parse", 0,
185 "AC3 audio stream parser");
186
187 object_class->finalize = gst_ac3_parse_finalize;
188
189 gst_element_class_add_static_pad_template (element_class, &sink_template);
190 gst_element_class_add_static_pad_template (element_class, &src_template);
191
192 gst_element_class_set_static_metadata (element_class,
193 "AC3 audio stream parser", "Codec/Parser/Converter/Audio",
194 "AC3 parser", "Tim-Philipp Müller <tim centricular net>");
195
196 parse_class->start = GST_DEBUG_FUNCPTR (gst_ac3_parse_start);
197 parse_class->stop = GST_DEBUG_FUNCPTR (gst_ac3_parse_stop);
198 parse_class->handle_frame = GST_DEBUG_FUNCPTR (gst_ac3_parse_handle_frame);
199 parse_class->pre_push_frame =
200 GST_DEBUG_FUNCPTR (gst_ac3_parse_pre_push_frame);
201 parse_class->src_event = GST_DEBUG_FUNCPTR (gst_ac3_parse_src_event);
202 parse_class->get_sink_caps = GST_DEBUG_FUNCPTR (gst_ac3_parse_get_sink_caps);
203 parse_class->set_sink_caps = GST_DEBUG_FUNCPTR (gst_ac3_parse_set_sink_caps);
204 }
205
206 static void
gst_ac3_parse_reset(GstAc3Parse * ac3parse)207 gst_ac3_parse_reset (GstAc3Parse * ac3parse)
208 {
209 ac3parse->channels = -1;
210 ac3parse->sample_rate = -1;
211 ac3parse->blocks = -1;
212 ac3parse->eac = FALSE;
213 ac3parse->sent_codec_tag = FALSE;
214 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_NONE);
215 }
216
217 static void
gst_ac3_parse_init(GstAc3Parse * ac3parse)218 gst_ac3_parse_init (GstAc3Parse * ac3parse)
219 {
220 gst_base_parse_set_min_frame_size (GST_BASE_PARSE (ac3parse), 8);
221 gst_ac3_parse_reset (ac3parse);
222 ac3parse->baseparse_chainfunc =
223 GST_BASE_PARSE_SINK_PAD (GST_BASE_PARSE (ac3parse))->chainfunc;
224 GST_PAD_SET_ACCEPT_INTERSECT (GST_BASE_PARSE_SINK_PAD (ac3parse));
225 GST_PAD_SET_ACCEPT_TEMPLATE (GST_BASE_PARSE_SINK_PAD (ac3parse));
226 }
227
228 static void
gst_ac3_parse_finalize(GObject * object)229 gst_ac3_parse_finalize (GObject * object)
230 {
231 G_OBJECT_CLASS (parent_class)->finalize (object);
232 }
233
234 static gboolean
gst_ac3_parse_start(GstBaseParse * parse)235 gst_ac3_parse_start (GstBaseParse * parse)
236 {
237 GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
238
239 GST_DEBUG_OBJECT (parse, "starting");
240
241 gst_ac3_parse_reset (ac3parse);
242
243 return TRUE;
244 }
245
246 static gboolean
gst_ac3_parse_stop(GstBaseParse * parse)247 gst_ac3_parse_stop (GstBaseParse * parse)
248 {
249 GST_DEBUG_OBJECT (parse, "stopping");
250
251 return TRUE;
252 }
253
254 static void
gst_ac3_parse_set_alignment(GstAc3Parse * ac3parse,gboolean eac)255 gst_ac3_parse_set_alignment (GstAc3Parse * ac3parse, gboolean eac)
256 {
257 GstCaps *caps;
258 GstStructure *st;
259 const gchar *str = NULL;
260 int i;
261
262 if (G_LIKELY (!eac))
263 goto done;
264
265 caps = gst_pad_get_allowed_caps (GST_BASE_PARSE_SRC_PAD (ac3parse));
266
267 if (!caps)
268 goto done;
269
270 for (i = 0; i < gst_caps_get_size (caps); i++) {
271 st = gst_caps_get_structure (caps, i);
272
273 if (!g_str_equal (gst_structure_get_name (st), "audio/x-eac3"))
274 continue;
275
276 if ((str = gst_structure_get_string (st, "alignment"))) {
277 if (g_str_equal (str, "iec61937")) {
278 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_IEC61937);
279 GST_DEBUG_OBJECT (ac3parse, "picked iec61937 alignment");
280 } else if (g_str_equal (str, "frame") == 0) {
281 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_FRAME);
282 GST_DEBUG_OBJECT (ac3parse, "picked frame alignment");
283 } else {
284 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_FRAME);
285 GST_WARNING_OBJECT (ac3parse, "unknown alignment: %s", str);
286 }
287 break;
288 }
289 }
290
291 if (caps)
292 gst_caps_unref (caps);
293
294 done:
295 /* default */
296 if (ac3parse->align == GST_AC3_PARSE_ALIGN_NONE) {
297 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_FRAME);
298 GST_DEBUG_OBJECT (ac3parse, "picked syncframe alignment");
299 }
300 }
301
302 static gboolean
gst_ac3_parse_frame_header_ac3(GstAc3Parse * ac3parse,GstBuffer * buf,gint skip,guint * frame_size,guint * rate,guint * chans,guint * blks,guint * sid)303 gst_ac3_parse_frame_header_ac3 (GstAc3Parse * ac3parse, GstBuffer * buf,
304 gint skip, guint * frame_size, guint * rate, guint * chans, guint * blks,
305 guint * sid)
306 {
307 GstBitReader bits;
308 GstMapInfo map;
309 guint8 fscod, frmsizcod, bsid, acmod, lfe_on, rate_scale;
310 gboolean ret = FALSE;
311
312 GST_LOG_OBJECT (ac3parse, "parsing ac3");
313
314 gst_buffer_map (buf, &map, GST_MAP_READ);
315 gst_bit_reader_init (&bits, map.data, map.size);
316 gst_bit_reader_skip_unchecked (&bits, skip * 8);
317
318 gst_bit_reader_skip_unchecked (&bits, 16 + 16);
319 fscod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2);
320 frmsizcod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 6);
321
322 if (G_UNLIKELY (fscod == 3 || frmsizcod >= G_N_ELEMENTS (frmsizcod_table))) {
323 GST_DEBUG_OBJECT (ac3parse, "bad fscod=%d frmsizcod=%d", fscod, frmsizcod);
324 goto cleanup;
325 }
326
327 bsid = gst_bit_reader_get_bits_uint8_unchecked (&bits, 5);
328 gst_bit_reader_skip_unchecked (&bits, 3); /* bsmod */
329 acmod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 3);
330
331 /* spec not quite clear here: decoder should decode if less than 8,
332 * but seemingly only defines 6 and 8 cases */
333 /* Files with 9 and 10 happen, and seem to comply with the <= 8
334 format, so let them through. The spec says nothing about 9 and 10 */
335 if (bsid > 10) {
336 GST_DEBUG_OBJECT (ac3parse, "unexpected bsid=%d", bsid);
337 goto cleanup;
338 } else if (bsid != 8 && bsid != 6) {
339 GST_DEBUG_OBJECT (ac3parse, "undefined bsid=%d", bsid);
340 }
341
342 if ((acmod & 0x1) && (acmod != 0x1)) /* 3 front channels */
343 gst_bit_reader_skip_unchecked (&bits, 2);
344 if ((acmod & 0x4)) /* if a surround channel exists */
345 gst_bit_reader_skip_unchecked (&bits, 2);
346 if (acmod == 0x2) /* if in 2/0 mode */
347 gst_bit_reader_skip_unchecked (&bits, 2);
348
349 lfe_on = gst_bit_reader_get_bits_uint8_unchecked (&bits, 1);
350
351 /* 6/8->0, 9->1, 10->2,
352 see http://matroska.org/technical/specs/codecid/index.html */
353 rate_scale = (CLAMP (bsid, 8, 10) - 8);
354
355 if (frame_size)
356 *frame_size = frmsizcod_table[frmsizcod].frame_size[fscod] * 2;
357 if (rate)
358 *rate = fscod_rates[fscod] >> rate_scale;
359 if (chans)
360 *chans = acmod_chans[acmod] + lfe_on;
361 if (blks)
362 *blks = 6;
363 if (sid)
364 *sid = 0;
365
366 ret = TRUE;
367
368 cleanup:
369 gst_buffer_unmap (buf, &map);
370
371 return ret;
372 }
373
374 static gboolean
gst_ac3_parse_frame_header_eac3(GstAc3Parse * ac3parse,GstBuffer * buf,gint skip,guint * frame_size,guint * rate,guint * chans,guint * blks,guint * sid)375 gst_ac3_parse_frame_header_eac3 (GstAc3Parse * ac3parse, GstBuffer * buf,
376 gint skip, guint * frame_size, guint * rate, guint * chans, guint * blks,
377 guint * sid)
378 {
379 GstBitReader bits;
380 GstMapInfo map;
381 guint16 frmsiz, sample_rate, blocks;
382 guint8 strmtyp, fscod, fscod2, acmod, lfe_on, strmid, numblkscod;
383 gboolean ret = FALSE;
384
385 GST_LOG_OBJECT (ac3parse, "parsing e-ac3");
386
387 gst_buffer_map (buf, &map, GST_MAP_READ);
388 gst_bit_reader_init (&bits, map.data, map.size);
389 gst_bit_reader_skip_unchecked (&bits, skip * 8);
390
391 gst_bit_reader_skip_unchecked (&bits, 16);
392 strmtyp = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2); /* strmtyp */
393 if (G_UNLIKELY (strmtyp == 3)) {
394 GST_DEBUG_OBJECT (ac3parse, "bad strmtyp %d", strmtyp);
395 goto cleanup;
396 }
397
398 strmid = gst_bit_reader_get_bits_uint8_unchecked (&bits, 3); /* substreamid */
399 frmsiz = gst_bit_reader_get_bits_uint16_unchecked (&bits, 11); /* frmsiz */
400 fscod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2); /* fscod */
401 if (fscod == 3) {
402 fscod2 = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2); /* fscod2 */
403 if (G_UNLIKELY (fscod2 == 3)) {
404 GST_DEBUG_OBJECT (ac3parse, "invalid fscod2");
405 goto cleanup;
406 }
407 sample_rate = fscod_rates[fscod2] / 2;
408 blocks = 6;
409 } else {
410 numblkscod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2); /* numblkscod */
411 sample_rate = fscod_rates[fscod];
412 blocks = numblks[numblkscod];
413 }
414
415 acmod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 3); /* acmod */
416 lfe_on = gst_bit_reader_get_bits_uint8_unchecked (&bits, 1); /* lfeon */
417
418 gst_bit_reader_skip_unchecked (&bits, 5); /* bsid */
419
420 if (frame_size)
421 *frame_size = (frmsiz + 1) * 2;
422 if (rate)
423 *rate = sample_rate;
424 if (chans)
425 *chans = acmod_chans[acmod] + lfe_on;
426 if (blks)
427 *blks = blocks;
428 if (sid)
429 *sid = (strmtyp & 0x1) << 3 | strmid;
430
431 ret = TRUE;
432
433 cleanup:
434 gst_buffer_unmap (buf, &map);
435
436 return ret;
437 }
438
439 static gboolean
gst_ac3_parse_frame_header(GstAc3Parse * parse,GstBuffer * buf,gint skip,guint * framesize,guint * rate,guint * chans,guint * blocks,guint * sid,gboolean * eac)440 gst_ac3_parse_frame_header (GstAc3Parse * parse, GstBuffer * buf, gint skip,
441 guint * framesize, guint * rate, guint * chans, guint * blocks,
442 guint * sid, gboolean * eac)
443 {
444 GstBitReader bits;
445 guint16 sync;
446 guint8 bsid;
447 GstMapInfo map;
448 gboolean ret = FALSE;
449
450 gst_buffer_map (buf, &map, GST_MAP_READ);
451 gst_bit_reader_init (&bits, map.data, map.size);
452
453 GST_MEMDUMP_OBJECT (parse, "AC3 frame sync", map.data, MIN (map.size, 16));
454
455 gst_bit_reader_skip_unchecked (&bits, skip * 8);
456
457 sync = gst_bit_reader_get_bits_uint16_unchecked (&bits, 16);
458 gst_bit_reader_skip_unchecked (&bits, 16 + 8);
459 bsid = gst_bit_reader_peek_bits_uint8_unchecked (&bits, 5);
460
461 if (G_UNLIKELY (sync != 0x0b77))
462 goto cleanup;
463
464 GST_LOG_OBJECT (parse, "bsid = %d", bsid);
465
466 if (bsid <= 10) {
467 if (eac)
468 *eac = FALSE;
469 ret = gst_ac3_parse_frame_header_ac3 (parse, buf, skip, framesize, rate,
470 chans, blocks, sid);
471 goto cleanup;
472 } else if (bsid <= 16) {
473 if (eac)
474 *eac = TRUE;
475 ret = gst_ac3_parse_frame_header_eac3 (parse, buf, skip, framesize, rate,
476 chans, blocks, sid);
477 goto cleanup;
478 } else {
479 GST_DEBUG_OBJECT (parse, "unexpected bsid %d", bsid);
480 ret = FALSE;
481 goto cleanup;
482 }
483
484 GST_DEBUG_OBJECT (parse, "unexpected bsid %d", bsid);
485
486 cleanup:
487 gst_buffer_unmap (buf, &map);
488
489 return ret;
490 }
491
492 static GstFlowReturn
gst_ac3_parse_handle_frame(GstBaseParse * parse,GstBaseParseFrame * frame,gint * skipsize)493 gst_ac3_parse_handle_frame (GstBaseParse * parse,
494 GstBaseParseFrame * frame, gint * skipsize)
495 {
496 GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
497 GstBuffer *buf = frame->buffer;
498 GstByteReader reader;
499 gint off;
500 gboolean lost_sync, draining, eac, more = FALSE;
501 guint frmsiz, blocks, sid;
502 guint rate, chans;
503 gboolean update_rate = FALSE;
504 gint framesize = 0;
505 gint have_blocks = 0;
506 GstMapInfo map;
507 gboolean ret = FALSE;
508 GstFlowReturn res = GST_FLOW_OK;
509
510 gst_buffer_map (buf, &map, GST_MAP_READ);
511
512 if (G_UNLIKELY (map.size < 8)) {
513 *skipsize = 1;
514 goto cleanup;
515 }
516
517 gst_byte_reader_init (&reader, map.data, map.size);
518 off = gst_byte_reader_masked_scan_uint32 (&reader, 0xffff0000, 0x0b770000,
519 0, map.size);
520
521 GST_LOG_OBJECT (parse, "possible sync at buffer offset %d", off);
522
523 /* didn't find anything that looks like a sync word, skip */
524 if (off < 0) {
525 *skipsize = map.size - 3;
526 goto cleanup;
527 }
528
529 /* possible frame header, but not at offset 0? skip bytes before sync */
530 if (off > 0) {
531 *skipsize = off;
532 goto cleanup;
533 }
534
535 /* make sure the values in the frame header look sane */
536 if (!gst_ac3_parse_frame_header (ac3parse, buf, 0, &frmsiz, &rate, &chans,
537 &blocks, &sid, &eac)) {
538 *skipsize = off + 2;
539 goto cleanup;
540 }
541
542 GST_LOG_OBJECT (parse, "size: %u, blocks: %u, rate: %u, chans: %u", frmsiz,
543 blocks, rate, chans);
544
545 framesize = frmsiz;
546
547 if (G_UNLIKELY (g_atomic_int_get (&ac3parse->align) ==
548 GST_AC3_PARSE_ALIGN_NONE))
549 gst_ac3_parse_set_alignment (ac3parse, eac);
550
551 GST_LOG_OBJECT (parse, "got frame");
552
553 lost_sync = GST_BASE_PARSE_LOST_SYNC (parse);
554 draining = GST_BASE_PARSE_DRAINING (parse);
555
556 if (g_atomic_int_get (&ac3parse->align) == GST_AC3_PARSE_ALIGN_IEC61937) {
557 /* We need 6 audio blocks from each substream, so we keep going forwards
558 * till we have it */
559
560 g_assert (blocks > 0);
561 GST_LOG_OBJECT (ac3parse, "Need %d frames before pushing", 6 / blocks);
562
563 if (sid != 0) {
564 /* We need the first substream to be the one with id 0 */
565 GST_LOG_OBJECT (ac3parse, "Skipping till we find sid 0");
566 *skipsize = off + 2;
567 goto cleanup;
568 }
569
570 framesize = 0;
571
572 /* Loop till we have 6 blocks per substream */
573 for (have_blocks = 0; !more && have_blocks < 6; have_blocks += blocks) {
574 /* Loop till we get one frame from each substream */
575 do {
576 framesize += frmsiz;
577
578 if (!gst_byte_reader_skip (&reader, frmsiz)
579 || map.size < (framesize + 6)) {
580 more = TRUE;
581 break;
582 }
583
584 if (!gst_ac3_parse_frame_header (ac3parse, buf, framesize, &frmsiz,
585 NULL, NULL, NULL, &sid, &eac)) {
586 *skipsize = off + 2;
587 goto cleanup;
588 }
589 } while (sid);
590 }
591
592 /* We're now at the next frame, so no need to skip if resyncing */
593 frmsiz = 0;
594 }
595
596 if (lost_sync && !draining) {
597 guint16 word = 0;
598
599 GST_DEBUG_OBJECT (ac3parse, "resyncing; checking next frame syncword");
600
601 if (more || !gst_byte_reader_skip (&reader, frmsiz) ||
602 !gst_byte_reader_get_uint16_be (&reader, &word)) {
603 GST_DEBUG_OBJECT (ac3parse, "... but not sufficient data");
604 gst_base_parse_set_min_frame_size (parse, framesize + 8);
605 *skipsize = 0;
606 goto cleanup;
607 } else {
608 if (word != 0x0b77) {
609 GST_DEBUG_OBJECT (ac3parse, "0x%x not OK", word);
610 *skipsize = off + 2;
611 goto cleanup;
612 } else {
613 /* ok, got sync now, let's assume constant frame size */
614 gst_base_parse_set_min_frame_size (parse, framesize);
615 }
616 }
617 }
618
619 /* expect to have found a frame here */
620 g_assert (framesize);
621 ret = TRUE;
622
623 /* arrange for metadata setup */
624 if (G_UNLIKELY (sid)) {
625 /* dependent frame, no need to (ac)count for or consider further */
626 GST_LOG_OBJECT (parse, "sid: %d", sid);
627 frame->flags |= GST_BASE_PARSE_FRAME_FLAG_NO_FRAME;
628 /* TODO maybe also mark as DELTA_UNIT,
629 * if that does not surprise baseparse elsewhere */
630 /* occupies same time space as previous base frame */
631 if (G_LIKELY (GST_BUFFER_TIMESTAMP (buf) >= GST_BUFFER_DURATION (buf)))
632 GST_BUFFER_TIMESTAMP (buf) -= GST_BUFFER_DURATION (buf);
633 /* only shortcut if we already arranged for caps */
634 if (G_LIKELY (ac3parse->sample_rate > 0))
635 goto cleanup;
636 }
637
638 if (G_UNLIKELY (ac3parse->sample_rate != rate || ac3parse->channels != chans
639 || ac3parse->eac != eac)) {
640 GstCaps *caps = gst_caps_new_simple (eac ? "audio/x-eac3" : "audio/x-ac3",
641 "framed", G_TYPE_BOOLEAN, TRUE, "rate", G_TYPE_INT, rate,
642 "channels", G_TYPE_INT, chans, NULL);
643 gst_caps_set_simple (caps, "alignment", G_TYPE_STRING,
644 g_atomic_int_get (&ac3parse->align) == GST_AC3_PARSE_ALIGN_IEC61937 ?
645 "iec61937" : "frame", NULL);
646 gst_pad_set_caps (GST_BASE_PARSE_SRC_PAD (parse), caps);
647 gst_caps_unref (caps);
648
649 ac3parse->sample_rate = rate;
650 ac3parse->channels = chans;
651 ac3parse->eac = eac;
652
653 update_rate = TRUE;
654 }
655
656 if (G_UNLIKELY (ac3parse->blocks != blocks)) {
657 ac3parse->blocks = blocks;
658
659 update_rate = TRUE;
660 }
661
662 if (G_UNLIKELY (update_rate))
663 gst_base_parse_set_frame_rate (parse, rate, 256 * blocks, 2, 2);
664
665 cleanup:
666 gst_buffer_unmap (buf, &map);
667
668 if (ret && framesize <= map.size) {
669 res = gst_base_parse_finish_frame (parse, frame, framesize);
670 }
671
672 return res;
673 }
674
675
676 /*
677 * MPEG-PS private1 streams add a 2 bytes "Audio Substream Headers" for each
678 * buffer (not each frame) with the offset of the next frame's start.
679 *
680 * Buffer 1:
681 * -------------------------------------------
682 * |firstAccUnit|AC3SyncWord|xxxxxxxxxxxxxxxxx
683 * -------------------------------------------
684 * Buffer 2:
685 * -------------------------------------------
686 * |firstAccUnit|xxxxxx|AC3SyncWord|xxxxxxxxxx
687 * -------------------------------------------
688 *
689 * These 2 bytes can be dropped safely as they do not include any timing
690 * information, only the offset to the start of the next frame.
691 *
692 * From http://stnsoft.com/DVD/ass-hdr.html:
693 * "FirstAccUnit offset to frame which corresponds to PTS value offset 0 is the
694 * last byte of FirstAccUnit, ie add the offset of byte 2 to get the AU's offset
695 * The value 0000 indicates there is no first access unit"
696 * */
697
698 static GstFlowReturn
gst_ac3_parse_chain_priv(GstPad * pad,GstObject * parent,GstBuffer * buf)699 gst_ac3_parse_chain_priv (GstPad * pad, GstObject * parent, GstBuffer * buf)
700 {
701 GstAc3Parse *ac3parse = GST_AC3_PARSE (parent);
702 GstFlowReturn ret;
703 gsize size;
704 guint8 data[2];
705 gint offset;
706 gint len;
707 GstBuffer *subbuf;
708 gint first_access;
709
710 size = gst_buffer_get_size (buf);
711 if (size < 2)
712 goto not_enough_data;
713
714 gst_buffer_extract (buf, 0, data, 2);
715 first_access = (data[0] << 8) | data[1];
716
717 /* Skip the first_access header */
718 offset = 2;
719
720 if (first_access > 1) {
721 /* Length of data before first_access */
722 len = first_access - 1;
723
724 if (len <= 0 || offset + len > size)
725 goto bad_first_access_parameter;
726
727 subbuf = gst_buffer_copy_region (buf, GST_BUFFER_COPY_ALL, offset, len);
728 GST_BUFFER_DTS (subbuf) = GST_CLOCK_TIME_NONE;
729 GST_BUFFER_PTS (subbuf) = GST_CLOCK_TIME_NONE;
730 ret = ac3parse->baseparse_chainfunc (pad, parent, subbuf);
731 if (ret != GST_FLOW_OK && ret != GST_FLOW_NOT_LINKED) {
732 gst_buffer_unref (buf);
733 goto done;
734 }
735
736 offset += len;
737 len = size - offset;
738
739 if (len > 0) {
740 subbuf = gst_buffer_copy_region (buf, GST_BUFFER_COPY_ALL, offset, len);
741 GST_BUFFER_PTS (subbuf) = GST_BUFFER_PTS (buf);
742 GST_BUFFER_DTS (subbuf) = GST_BUFFER_DTS (buf);
743
744 ret = ac3parse->baseparse_chainfunc (pad, parent, subbuf);
745 }
746 gst_buffer_unref (buf);
747 } else {
748 /* first_access = 0 or 1, so if there's a timestamp it applies to the first byte */
749 subbuf =
750 gst_buffer_copy_region (buf, GST_BUFFER_COPY_ALL, offset,
751 size - offset);
752 GST_BUFFER_PTS (subbuf) = GST_BUFFER_PTS (buf);
753 GST_BUFFER_DTS (subbuf) = GST_BUFFER_DTS (buf);
754 gst_buffer_unref (buf);
755 ret = ac3parse->baseparse_chainfunc (pad, parent, subbuf);
756 }
757
758 done:
759 return ret;
760
761 /* ERRORS */
762 not_enough_data:
763 {
764 GST_ELEMENT_ERROR (GST_ELEMENT (ac3parse), STREAM, FORMAT, (NULL),
765 ("Insufficient data in buffer. Can't determine first_acess"));
766 gst_buffer_unref (buf);
767 return GST_FLOW_ERROR;
768 }
769 bad_first_access_parameter:
770 {
771 GST_ELEMENT_ERROR (GST_ELEMENT (ac3parse), STREAM, FORMAT, (NULL),
772 ("Bad first_access parameter (%d) in buffer", first_access));
773 gst_buffer_unref (buf);
774 return GST_FLOW_ERROR;
775 }
776 }
777
778 static GstFlowReturn
gst_ac3_parse_pre_push_frame(GstBaseParse * parse,GstBaseParseFrame * frame)779 gst_ac3_parse_pre_push_frame (GstBaseParse * parse, GstBaseParseFrame * frame)
780 {
781 GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
782
783 if (!ac3parse->sent_codec_tag) {
784 GstTagList *taglist;
785 GstCaps *caps;
786
787 /* codec tag */
788 caps = gst_pad_get_current_caps (GST_BASE_PARSE_SRC_PAD (parse));
789 if (G_UNLIKELY (caps == NULL)) {
790 if (GST_PAD_IS_FLUSHING (GST_BASE_PARSE_SRC_PAD (parse))) {
791 GST_INFO_OBJECT (parse, "Src pad is flushing");
792 return GST_FLOW_FLUSHING;
793 } else {
794 GST_INFO_OBJECT (parse, "Src pad is not negotiated!");
795 return GST_FLOW_NOT_NEGOTIATED;
796 }
797 }
798
799 taglist = gst_tag_list_new_empty ();
800 gst_pb_utils_add_codec_description_to_tag_list (taglist,
801 GST_TAG_AUDIO_CODEC, caps);
802 gst_caps_unref (caps);
803
804 gst_base_parse_merge_tags (parse, taglist, GST_TAG_MERGE_REPLACE);
805 gst_tag_list_unref (taglist);
806
807 /* also signals the end of first-frame processing */
808 ac3parse->sent_codec_tag = TRUE;
809 }
810
811 return GST_FLOW_OK;
812 }
813
814 static gboolean
gst_ac3_parse_src_event(GstBaseParse * parse,GstEvent * event)815 gst_ac3_parse_src_event (GstBaseParse * parse, GstEvent * event)
816 {
817 GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
818
819 if (G_UNLIKELY (GST_EVENT_TYPE (event) == GST_EVENT_CUSTOM_UPSTREAM) &&
820 gst_event_has_name (event, "ac3parse-set-alignment")) {
821 const GstStructure *st = gst_event_get_structure (event);
822 const gchar *align = gst_structure_get_string (st, "alignment");
823
824 if (g_str_equal (align, "iec61937")) {
825 GST_DEBUG_OBJECT (ac3parse, "Switching to iec61937 alignment");
826 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_IEC61937);
827 } else if (g_str_equal (align, "frame")) {
828 GST_DEBUG_OBJECT (ac3parse, "Switching to frame alignment");
829 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_FRAME);
830 } else {
831 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_FRAME);
832 GST_WARNING_OBJECT (ac3parse, "Got unknown alignment request (%s) "
833 "reverting to frame alignment.",
834 gst_structure_get_string (st, "alignment"));
835 }
836
837 gst_event_unref (event);
838 return TRUE;
839 }
840
841 return GST_BASE_PARSE_CLASS (parent_class)->src_event (parse, event);
842 }
843
844 static void
remove_fields(GstCaps * caps)845 remove_fields (GstCaps * caps)
846 {
847 guint i, n;
848
849 n = gst_caps_get_size (caps);
850 for (i = 0; i < n; i++) {
851 GstStructure *s = gst_caps_get_structure (caps, i);
852
853 gst_structure_remove_field (s, "framed");
854 gst_structure_remove_field (s, "alignment");
855 }
856 }
857
858 static GstCaps *
extend_caps(GstCaps * caps,gboolean add_private)859 extend_caps (GstCaps * caps, gboolean add_private)
860 {
861 guint i, n;
862 GstCaps *ncaps = gst_caps_new_empty ();
863
864 n = gst_caps_get_size (caps);
865 for (i = 0; i < n; i++) {
866 GstStructure *s = gst_caps_get_structure (caps, i);
867
868 if (add_private && !gst_structure_has_name (s, "audio/x-private1-ac3")) {
869 GstStructure *ns = gst_structure_copy (s);
870 gst_structure_set_name (ns, "audio/x-private1-ac3");
871 gst_caps_append_structure (ncaps, ns);
872 } else if (!add_private &&
873 gst_structure_has_name (s, "audio/x-private1-ac3")) {
874 GstStructure *ns = gst_structure_copy (s);
875 gst_structure_set_name (ns, "audio/x-ac3");
876 gst_caps_append_structure (ncaps, ns);
877 ns = gst_structure_copy (s);
878 gst_structure_set_name (ns, "audio/x-eac3");
879 gst_caps_append_structure (ncaps, ns);
880 } else if (!add_private) {
881 gst_caps_append_structure (ncaps, gst_structure_copy (s));
882 }
883 }
884
885 if (add_private) {
886 gst_caps_append (caps, ncaps);
887 } else {
888 gst_caps_unref (caps);
889 caps = ncaps;
890 }
891
892 return caps;
893 }
894
895 static GstCaps *
gst_ac3_parse_get_sink_caps(GstBaseParse * parse,GstCaps * filter)896 gst_ac3_parse_get_sink_caps (GstBaseParse * parse, GstCaps * filter)
897 {
898 GstCaps *peercaps, *templ;
899 GstCaps *res;
900
901 templ = gst_pad_get_pad_template_caps (GST_BASE_PARSE_SINK_PAD (parse));
902 if (filter) {
903 GstCaps *fcopy = gst_caps_copy (filter);
904 /* Remove the fields we convert */
905 remove_fields (fcopy);
906 /* we do not ask downstream to handle x-private1-ac3 */
907 fcopy = extend_caps (fcopy, FALSE);
908 peercaps = gst_pad_peer_query_caps (GST_BASE_PARSE_SRC_PAD (parse), fcopy);
909 gst_caps_unref (fcopy);
910 } else
911 peercaps = gst_pad_peer_query_caps (GST_BASE_PARSE_SRC_PAD (parse), NULL);
912
913 if (peercaps) {
914 /* Remove the framed and alignment field. We can convert
915 * between different alignments. */
916 peercaps = gst_caps_make_writable (peercaps);
917 remove_fields (peercaps);
918 /* also allow for x-private1-ac3 input */
919 peercaps = extend_caps (peercaps, TRUE);
920
921 res = gst_caps_intersect_full (peercaps, templ, GST_CAPS_INTERSECT_FIRST);
922 gst_caps_unref (peercaps);
923 gst_caps_unref (templ);
924 } else {
925 res = templ;
926 }
927
928 if (filter) {
929 GstCaps *intersection;
930
931 intersection =
932 gst_caps_intersect_full (filter, res, GST_CAPS_INTERSECT_FIRST);
933 gst_caps_unref (res);
934 res = intersection;
935 }
936
937 return res;
938 }
939
940 static gboolean
gst_ac3_parse_set_sink_caps(GstBaseParse * parse,GstCaps * caps)941 gst_ac3_parse_set_sink_caps (GstBaseParse * parse, GstCaps * caps)
942 {
943 GstStructure *s;
944 GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
945
946 s = gst_caps_get_structure (caps, 0);
947 if (gst_structure_has_name (s, "audio/x-private1-ac3")) {
948 gst_pad_set_chain_function (parse->sinkpad, gst_ac3_parse_chain_priv);
949 } else {
950 gst_pad_set_chain_function (parse->sinkpad, ac3parse->baseparse_chainfunc);
951 }
952 return TRUE;
953 }
954