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 * @title: ac3parse
25 * @short_description: AC3 parser
26 * @see_also: #GstAmrParse, #GstAACParse
27 *
28 * This is an AC3 parser.
29 *
30 * ## Example launch line
31 * |[
32 * gst-launch-1.0 filesrc location=abc.ac3 ! ac3parse ! a52dec ! audioresample ! audioconvert ! autoaudiosink
33 * ]|
34 *
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 "gstaudioparserselements.h"
49 #include "gstac3parse.h"
50 #include <gst/base/base.h>
51 #include <gst/pbutils/pbutils.h>
52
53 GST_DEBUG_CATEGORY_STATIC (ac3_parse_debug);
54 #define GST_CAT_DEFAULT ac3_parse_debug
55
56 static const struct
57 {
58 const guint bit_rate; /* nominal bit rate */
59 const guint frame_size[3]; /* frame size for 32kHz, 44kHz, and 48kHz */
60 } frmsizcod_table[38] = {
61 {
62 32, {
63 64, 69, 96}}, {
64 32, {
65 64, 70, 96}}, {
66 40, {
67 80, 87, 120}}, {
68 40, {
69 80, 88, 120}}, {
70 48, {
71 96, 104, 144}}, {
72 48, {
73 96, 105, 144}}, {
74 56, {
75 112, 121, 168}}, {
76 56, {
77 112, 122, 168}}, {
78 64, {
79 128, 139, 192}}, {
80 64, {
81 128, 140, 192}}, {
82 80, {
83 160, 174, 240}}, {
84 80, {
85 160, 175, 240}}, {
86 96, {
87 192, 208, 288}}, {
88 96, {
89 192, 209, 288}}, {
90 112, {
91 224, 243, 336}}, {
92 112, {
93 224, 244, 336}}, {
94 128, {
95 256, 278, 384}}, {
96 128, {
97 256, 279, 384}}, {
98 160, {
99 320, 348, 480}}, {
100 160, {
101 320, 349, 480}}, {
102 192, {
103 384, 417, 576}}, {
104 192, {
105 384, 418, 576}}, {
106 224, {
107 448, 487, 672}}, {
108 224, {
109 448, 488, 672}}, {
110 256, {
111 512, 557, 768}}, {
112 256, {
113 512, 558, 768}}, {
114 320, {
115 640, 696, 960}}, {
116 320, {
117 640, 697, 960}}, {
118 384, {
119 768, 835, 1152}}, {
120 384, {
121 768, 836, 1152}}, {
122 448, {
123 896, 975, 1344}}, {
124 448, {
125 896, 976, 1344}}, {
126 512, {
127 1024, 1114, 1536}}, {
128 512, {
129 1024, 1115, 1536}}, {
130 576, {
131 1152, 1253, 1728}}, {
132 576, {
133 1152, 1254, 1728}}, {
134 640, {
135 1280, 1393, 1920}}, {
136 640, {
137 1280, 1394, 1920}}
138 };
139
140 static const guint fscod_rates[4] = { 48000, 44100, 32000, 0 };
141 static const guint acmod_chans[8] = { 2, 1, 2, 3, 3, 4, 4, 5 };
142 static const guint numblks[4] = { 1, 2, 3, 6 };
143
144 static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
145 GST_PAD_SRC,
146 GST_PAD_ALWAYS,
147 GST_STATIC_CAPS ("audio/x-ac3, framed = (boolean) true, "
148 " channels = (int) [ 1, 6 ], rate = (int) [ 8000, 48000 ], "
149 " alignment = (string) { iec61937, frame}; "
150 "audio/x-eac3, framed = (boolean) true, "
151 " channels = (int) [ 1, 6 ], rate = (int) [ 8000, 48000 ], "
152 " alignment = (string) { iec61937, frame}; "));
153
154 static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
155 GST_PAD_SINK,
156 GST_PAD_ALWAYS,
157 GST_STATIC_CAPS ("audio/x-ac3; " "audio/x-eac3; " "audio/ac3; "
158 "audio/x-private1-ac3"));
159
160 static void gst_ac3_parse_finalize (GObject * object);
161
162 static gboolean gst_ac3_parse_start (GstBaseParse * parse);
163 static gboolean gst_ac3_parse_stop (GstBaseParse * parse);
164 static GstFlowReturn gst_ac3_parse_handle_frame (GstBaseParse * parse,
165 GstBaseParseFrame * frame, gint * skipsize);
166 static GstFlowReturn gst_ac3_parse_pre_push_frame (GstBaseParse * parse,
167 GstBaseParseFrame * frame);
168 static gboolean gst_ac3_parse_src_event (GstBaseParse * parse,
169 GstEvent * event);
170 static GstCaps *gst_ac3_parse_get_sink_caps (GstBaseParse * parse,
171 GstCaps * filter);
172 static gboolean gst_ac3_parse_set_sink_caps (GstBaseParse * parse,
173 GstCaps * caps);
174
175 #define gst_ac3_parse_parent_class parent_class
176 G_DEFINE_TYPE (GstAc3Parse, gst_ac3_parse, GST_TYPE_BASE_PARSE);
177 GST_ELEMENT_REGISTER_DEFINE (ac3parse, "ac3parse",
178 GST_RANK_PRIMARY + 1, GST_TYPE_AC3_PARSE);
179
180 static void
gst_ac3_parse_class_init(GstAc3ParseClass * klass)181 gst_ac3_parse_class_init (GstAc3ParseClass * klass)
182 {
183 GObjectClass *object_class = G_OBJECT_CLASS (klass);
184 GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
185 GstBaseParseClass *parse_class = GST_BASE_PARSE_CLASS (klass);
186
187 GST_DEBUG_CATEGORY_INIT (ac3_parse_debug, "ac3parse", 0,
188 "AC3 audio stream parser");
189
190 object_class->finalize = gst_ac3_parse_finalize;
191
192 gst_element_class_add_static_pad_template (element_class, &sink_template);
193 gst_element_class_add_static_pad_template (element_class, &src_template);
194
195 gst_element_class_set_static_metadata (element_class,
196 "AC3 audio stream parser", "Codec/Parser/Converter/Audio",
197 "AC3 parser", "Tim-Philipp Müller <tim centricular net>");
198
199 parse_class->start = GST_DEBUG_FUNCPTR (gst_ac3_parse_start);
200 parse_class->stop = GST_DEBUG_FUNCPTR (gst_ac3_parse_stop);
201 parse_class->handle_frame = GST_DEBUG_FUNCPTR (gst_ac3_parse_handle_frame);
202 parse_class->pre_push_frame =
203 GST_DEBUG_FUNCPTR (gst_ac3_parse_pre_push_frame);
204 parse_class->src_event = GST_DEBUG_FUNCPTR (gst_ac3_parse_src_event);
205 parse_class->get_sink_caps = GST_DEBUG_FUNCPTR (gst_ac3_parse_get_sink_caps);
206 parse_class->set_sink_caps = GST_DEBUG_FUNCPTR (gst_ac3_parse_set_sink_caps);
207 }
208
209 static void
gst_ac3_parse_reset(GstAc3Parse * ac3parse)210 gst_ac3_parse_reset (GstAc3Parse * ac3parse)
211 {
212 ac3parse->channels = -1;
213 ac3parse->sample_rate = -1;
214 ac3parse->blocks = -1;
215 ac3parse->eac = FALSE;
216 ac3parse->sent_codec_tag = FALSE;
217 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_NONE);
218 }
219
220 static void
gst_ac3_parse_init(GstAc3Parse * ac3parse)221 gst_ac3_parse_init (GstAc3Parse * ac3parse)
222 {
223 gst_base_parse_set_min_frame_size (GST_BASE_PARSE (ac3parse), 8);
224 gst_ac3_parse_reset (ac3parse);
225 ac3parse->baseparse_chainfunc =
226 GST_BASE_PARSE_SINK_PAD (GST_BASE_PARSE (ac3parse))->chainfunc;
227 GST_PAD_SET_ACCEPT_INTERSECT (GST_BASE_PARSE_SINK_PAD (ac3parse));
228 GST_PAD_SET_ACCEPT_TEMPLATE (GST_BASE_PARSE_SINK_PAD (ac3parse));
229 }
230
231 static void
gst_ac3_parse_finalize(GObject * object)232 gst_ac3_parse_finalize (GObject * object)
233 {
234 G_OBJECT_CLASS (parent_class)->finalize (object);
235 }
236
237 static gboolean
gst_ac3_parse_start(GstBaseParse * parse)238 gst_ac3_parse_start (GstBaseParse * parse)
239 {
240 GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
241
242 GST_DEBUG_OBJECT (parse, "starting");
243
244 gst_ac3_parse_reset (ac3parse);
245
246 return TRUE;
247 }
248
249 static gboolean
gst_ac3_parse_stop(GstBaseParse * parse)250 gst_ac3_parse_stop (GstBaseParse * parse)
251 {
252 GST_DEBUG_OBJECT (parse, "stopping");
253
254 return TRUE;
255 }
256
257 static void
gst_ac3_parse_set_alignment(GstAc3Parse * ac3parse,gboolean eac)258 gst_ac3_parse_set_alignment (GstAc3Parse * ac3parse, gboolean eac)
259 {
260 GstCaps *caps;
261 GstStructure *st;
262 const gchar *str = NULL;
263 int i;
264
265 if (G_LIKELY (!eac))
266 goto done;
267
268 caps = gst_pad_get_allowed_caps (GST_BASE_PARSE_SRC_PAD (ac3parse));
269
270 if (!caps)
271 goto done;
272
273 for (i = 0; i < gst_caps_get_size (caps); i++) {
274 st = gst_caps_get_structure (caps, i);
275
276 if (!g_str_equal (gst_structure_get_name (st), "audio/x-eac3"))
277 continue;
278
279 if ((str = gst_structure_get_string (st, "alignment"))) {
280 if (g_str_equal (str, "iec61937")) {
281 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_IEC61937);
282 GST_DEBUG_OBJECT (ac3parse, "picked iec61937 alignment");
283 } else if (g_str_equal (str, "frame") == 0) {
284 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_FRAME);
285 GST_DEBUG_OBJECT (ac3parse, "picked frame alignment");
286 } else {
287 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_FRAME);
288 GST_WARNING_OBJECT (ac3parse, "unknown alignment: %s", str);
289 }
290 break;
291 }
292 }
293
294 if (caps)
295 gst_caps_unref (caps);
296
297 done:
298 /* default */
299 if (ac3parse->align == GST_AC3_PARSE_ALIGN_NONE) {
300 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_FRAME);
301 GST_DEBUG_OBJECT (ac3parse, "picked syncframe alignment");
302 }
303 }
304
305 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)306 gst_ac3_parse_frame_header_ac3 (GstAc3Parse * ac3parse, GstBuffer * buf,
307 gint skip, guint * frame_size, guint * rate, guint * chans, guint * blks,
308 guint * sid)
309 {
310 GstBitReader bits;
311 GstMapInfo map;
312 guint8 fscod, frmsizcod, bsid, acmod, lfe_on, rate_scale;
313 gboolean ret = FALSE;
314
315 GST_LOG_OBJECT (ac3parse, "parsing ac3");
316
317 gst_buffer_map (buf, &map, GST_MAP_READ);
318 gst_bit_reader_init (&bits, map.data, map.size);
319 gst_bit_reader_skip_unchecked (&bits, skip * 8);
320
321 gst_bit_reader_skip_unchecked (&bits, 16 + 16);
322 fscod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2);
323 frmsizcod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 6);
324
325 if (G_UNLIKELY (fscod == 3 || frmsizcod >= G_N_ELEMENTS (frmsizcod_table))) {
326 GST_DEBUG_OBJECT (ac3parse, "bad fscod=%d frmsizcod=%d", fscod, frmsizcod);
327 goto cleanup;
328 }
329
330 bsid = gst_bit_reader_get_bits_uint8_unchecked (&bits, 5);
331 gst_bit_reader_skip_unchecked (&bits, 3); /* bsmod */
332 acmod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 3);
333
334 /* spec not quite clear here: decoder should decode if less than 8,
335 * but seemingly only defines 6 and 8 cases */
336 /* Files with 9 and 10 happen, and seem to comply with the <= 8
337 format, so let them through. The spec says nothing about 9 and 10 */
338 if (bsid > 10) {
339 GST_DEBUG_OBJECT (ac3parse, "unexpected bsid=%d", bsid);
340 goto cleanup;
341 } else if (bsid != 8 && bsid != 6) {
342 GST_DEBUG_OBJECT (ac3parse, "undefined bsid=%d", bsid);
343 }
344
345 if ((acmod & 0x1) && (acmod != 0x1)) /* 3 front channels */
346 gst_bit_reader_skip_unchecked (&bits, 2);
347 if ((acmod & 0x4)) /* if a surround channel exists */
348 gst_bit_reader_skip_unchecked (&bits, 2);
349 if (acmod == 0x2) /* if in 2/0 mode */
350 gst_bit_reader_skip_unchecked (&bits, 2);
351
352 lfe_on = gst_bit_reader_get_bits_uint8_unchecked (&bits, 1);
353
354 /* 6/8->0, 9->1, 10->2,
355 see http://matroska.org/technical/specs/codecid/index.html */
356 rate_scale = (CLAMP (bsid, 8, 10) - 8);
357
358 if (frame_size)
359 *frame_size = frmsizcod_table[frmsizcod].frame_size[fscod] * 2;
360 if (rate)
361 *rate = fscod_rates[fscod] >> rate_scale;
362 if (chans)
363 *chans = acmod_chans[acmod] + lfe_on;
364 if (blks)
365 *blks = 6;
366 if (sid)
367 *sid = 0;
368
369 ret = TRUE;
370
371 cleanup:
372 gst_buffer_unmap (buf, &map);
373
374 return ret;
375 }
376
377 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)378 gst_ac3_parse_frame_header_eac3 (GstAc3Parse * ac3parse, GstBuffer * buf,
379 gint skip, guint * frame_size, guint * rate, guint * chans, guint * blks,
380 guint * sid)
381 {
382 GstBitReader bits;
383 GstMapInfo map;
384 guint16 frmsiz, sample_rate, blocks;
385 guint8 strmtyp, fscod, fscod2, acmod, lfe_on, strmid, numblkscod;
386 gboolean ret = FALSE;
387
388 GST_LOG_OBJECT (ac3parse, "parsing e-ac3");
389
390 gst_buffer_map (buf, &map, GST_MAP_READ);
391 gst_bit_reader_init (&bits, map.data, map.size);
392 gst_bit_reader_skip_unchecked (&bits, skip * 8);
393
394 gst_bit_reader_skip_unchecked (&bits, 16);
395 strmtyp = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2); /* strmtyp */
396 if (G_UNLIKELY (strmtyp == 3)) {
397 GST_DEBUG_OBJECT (ac3parse, "bad strmtyp %d", strmtyp);
398 goto cleanup;
399 }
400
401 strmid = gst_bit_reader_get_bits_uint8_unchecked (&bits, 3); /* substreamid */
402 frmsiz = gst_bit_reader_get_bits_uint16_unchecked (&bits, 11); /* frmsiz */
403 fscod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2); /* fscod */
404 if (fscod == 3) {
405 fscod2 = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2); /* fscod2 */
406 if (G_UNLIKELY (fscod2 == 3)) {
407 GST_DEBUG_OBJECT (ac3parse, "invalid fscod2");
408 goto cleanup;
409 }
410 sample_rate = fscod_rates[fscod2] / 2;
411 blocks = 6;
412 } else {
413 numblkscod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 2); /* numblkscod */
414 sample_rate = fscod_rates[fscod];
415 blocks = numblks[numblkscod];
416 }
417
418 acmod = gst_bit_reader_get_bits_uint8_unchecked (&bits, 3); /* acmod */
419 lfe_on = gst_bit_reader_get_bits_uint8_unchecked (&bits, 1); /* lfeon */
420
421 gst_bit_reader_skip_unchecked (&bits, 5); /* bsid */
422
423 if (frame_size)
424 *frame_size = (frmsiz + 1) * 2;
425 if (rate)
426 *rate = sample_rate;
427 if (chans)
428 *chans = acmod_chans[acmod] + lfe_on;
429 if (blks)
430 *blks = blocks;
431 if (sid)
432 *sid = (strmtyp & 0x1) << 3 | strmid;
433
434 ret = TRUE;
435
436 cleanup:
437 gst_buffer_unmap (buf, &map);
438
439 return ret;
440 }
441
442 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)443 gst_ac3_parse_frame_header (GstAc3Parse * parse, GstBuffer * buf, gint skip,
444 guint * framesize, guint * rate, guint * chans, guint * blocks,
445 guint * sid, gboolean * eac)
446 {
447 GstBitReader bits;
448 guint16 sync;
449 guint8 bsid;
450 GstMapInfo map;
451 gboolean ret = FALSE;
452
453 gst_buffer_map (buf, &map, GST_MAP_READ);
454 gst_bit_reader_init (&bits, map.data, map.size);
455
456 GST_MEMDUMP_OBJECT (parse, "AC3 frame sync", map.data, MIN (map.size, 16));
457
458 gst_bit_reader_skip_unchecked (&bits, skip * 8);
459
460 sync = gst_bit_reader_get_bits_uint16_unchecked (&bits, 16);
461 gst_bit_reader_skip_unchecked (&bits, 16 + 8);
462 bsid = gst_bit_reader_peek_bits_uint8_unchecked (&bits, 5);
463
464 if (G_UNLIKELY (sync != 0x0b77))
465 goto cleanup;
466
467 GST_LOG_OBJECT (parse, "bsid = %d", bsid);
468
469 if (bsid <= 10) {
470 if (eac)
471 *eac = FALSE;
472 ret = gst_ac3_parse_frame_header_ac3 (parse, buf, skip, framesize, rate,
473 chans, blocks, sid);
474 goto cleanup;
475 } else if (bsid <= 16) {
476 if (eac)
477 *eac = TRUE;
478 ret = gst_ac3_parse_frame_header_eac3 (parse, buf, skip, framesize, rate,
479 chans, blocks, sid);
480 goto cleanup;
481 } else {
482 GST_DEBUG_OBJECT (parse, "unexpected bsid %d", bsid);
483 ret = FALSE;
484 goto cleanup;
485 }
486
487 GST_DEBUG_OBJECT (parse, "unexpected bsid %d", bsid);
488
489 cleanup:
490 gst_buffer_unmap (buf, &map);
491
492 return ret;
493 }
494
495 static GstFlowReturn
gst_ac3_parse_handle_frame(GstBaseParse * parse,GstBaseParseFrame * frame,gint * skipsize)496 gst_ac3_parse_handle_frame (GstBaseParse * parse,
497 GstBaseParseFrame * frame, gint * skipsize)
498 {
499 GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
500 GstBuffer *buf = frame->buffer;
501 GstByteReader reader;
502 gint off;
503 gboolean lost_sync, draining, eac, more = FALSE;
504 guint frmsiz, blocks, sid;
505 guint rate, chans;
506 gboolean update_rate = FALSE;
507 gint framesize = 0;
508 gint have_blocks = 0;
509 GstMapInfo map;
510 gboolean ret = FALSE;
511 GstFlowReturn res = GST_FLOW_OK;
512
513 gst_buffer_map (buf, &map, GST_MAP_READ);
514
515 if (G_UNLIKELY (map.size < 8)) {
516 *skipsize = 1;
517 goto cleanup;
518 }
519
520 gst_byte_reader_init (&reader, map.data, map.size);
521 off = gst_byte_reader_masked_scan_uint32 (&reader, 0xffff0000, 0x0b770000,
522 0, map.size);
523
524 GST_LOG_OBJECT (parse, "possible sync at buffer offset %d", off);
525
526 /* didn't find anything that looks like a sync word, skip */
527 if (off < 0) {
528 *skipsize = map.size - 3;
529 goto cleanup;
530 }
531
532 /* possible frame header, but not at offset 0? skip bytes before sync */
533 if (off > 0) {
534 *skipsize = off;
535 goto cleanup;
536 }
537
538 /* make sure the values in the frame header look sane */
539 if (!gst_ac3_parse_frame_header (ac3parse, buf, 0, &frmsiz, &rate, &chans,
540 &blocks, &sid, &eac)) {
541 *skipsize = off + 2;
542 goto cleanup;
543 }
544
545 GST_LOG_OBJECT (parse, "size: %u, blocks: %u, rate: %u, chans: %u", frmsiz,
546 blocks, rate, chans);
547
548 framesize = frmsiz;
549
550 if (G_UNLIKELY (g_atomic_int_get (&ac3parse->align) ==
551 GST_AC3_PARSE_ALIGN_NONE))
552 gst_ac3_parse_set_alignment (ac3parse, eac);
553
554 GST_LOG_OBJECT (parse, "got frame");
555
556 lost_sync = GST_BASE_PARSE_LOST_SYNC (parse);
557 draining = GST_BASE_PARSE_DRAINING (parse);
558
559 if (g_atomic_int_get (&ac3parse->align) == GST_AC3_PARSE_ALIGN_IEC61937) {
560 /* We need 6 audio blocks from each substream, so we keep going forwards
561 * till we have it */
562
563 g_assert (blocks > 0);
564 GST_LOG_OBJECT (ac3parse, "Need %d frames before pushing", 6 / blocks);
565
566 if (sid != 0) {
567 /* We need the first substream to be the one with id 0 */
568 GST_LOG_OBJECT (ac3parse, "Skipping till we find sid 0");
569 *skipsize = off + 2;
570 goto cleanup;
571 }
572
573 framesize = 0;
574
575 /* Loop till we have 6 blocks per substream */
576 for (have_blocks = 0; !more && have_blocks < 6; have_blocks += blocks) {
577 /* Loop till we get one frame from each substream */
578 do {
579 framesize += frmsiz;
580
581 if (!gst_byte_reader_skip (&reader, frmsiz)
582 || map.size < (framesize + 6)) {
583 more = TRUE;
584 break;
585 }
586
587 if (!gst_ac3_parse_frame_header (ac3parse, buf, framesize, &frmsiz,
588 NULL, NULL, NULL, &sid, &eac)) {
589 *skipsize = off + 2;
590 goto cleanup;
591 }
592 } while (sid);
593 }
594
595 /* We're now at the next frame, so no need to skip if resyncing */
596 frmsiz = 0;
597 }
598
599 if (lost_sync && !draining) {
600 guint16 word = 0;
601
602 GST_DEBUG_OBJECT (ac3parse, "resyncing; checking next frame syncword");
603
604 if (more || !gst_byte_reader_skip (&reader, frmsiz) ||
605 !gst_byte_reader_get_uint16_be (&reader, &word)) {
606 GST_DEBUG_OBJECT (ac3parse, "... but not sufficient data");
607 gst_base_parse_set_min_frame_size (parse, framesize + 8);
608 *skipsize = 0;
609 goto cleanup;
610 } else {
611 if (word != 0x0b77) {
612 GST_DEBUG_OBJECT (ac3parse, "0x%x not OK", word);
613 *skipsize = off + 2;
614 goto cleanup;
615 } else {
616 /* ok, got sync now, let's assume constant frame size */
617 gst_base_parse_set_min_frame_size (parse, framesize);
618 }
619 }
620 }
621
622 /* expect to have found a frame here */
623 g_assert (framesize);
624 ret = TRUE;
625
626 /* arrange for metadata setup */
627 if (G_UNLIKELY (sid)) {
628 /* dependent frame, no need to (ac)count for or consider further */
629 GST_LOG_OBJECT (parse, "sid: %d", sid);
630 frame->flags |= GST_BASE_PARSE_FRAME_FLAG_NO_FRAME;
631 /* TODO maybe also mark as DELTA_UNIT,
632 * if that does not surprise baseparse elsewhere */
633 /* occupies same time space as previous base frame */
634 if (G_LIKELY (GST_BUFFER_TIMESTAMP (buf) >= GST_BUFFER_DURATION (buf)))
635 GST_BUFFER_TIMESTAMP (buf) -= GST_BUFFER_DURATION (buf);
636 /* only shortcut if we already arranged for caps */
637 if (G_LIKELY (ac3parse->sample_rate > 0))
638 goto cleanup;
639 }
640
641 if (G_UNLIKELY (ac3parse->sample_rate != rate || ac3parse->channels != chans
642 || ac3parse->eac != eac)) {
643 GstCaps *caps = gst_caps_new_simple (eac ? "audio/x-eac3" : "audio/x-ac3",
644 "framed", G_TYPE_BOOLEAN, TRUE, "rate", G_TYPE_INT, rate,
645 "channels", G_TYPE_INT, chans, NULL);
646 gst_caps_set_simple (caps, "alignment", G_TYPE_STRING,
647 g_atomic_int_get (&ac3parse->align) == GST_AC3_PARSE_ALIGN_IEC61937 ?
648 "iec61937" : "frame", NULL);
649 gst_pad_set_caps (GST_BASE_PARSE_SRC_PAD (parse), caps);
650 gst_caps_unref (caps);
651
652 ac3parse->sample_rate = rate;
653 ac3parse->channels = chans;
654 ac3parse->eac = eac;
655
656 update_rate = TRUE;
657 }
658
659 if (G_UNLIKELY (ac3parse->blocks != blocks)) {
660 ac3parse->blocks = blocks;
661
662 update_rate = TRUE;
663 }
664
665 if (G_UNLIKELY (update_rate))
666 gst_base_parse_set_frame_rate (parse, rate, 256 * blocks, 2, 2);
667
668 cleanup:
669 gst_buffer_unmap (buf, &map);
670
671 if (ret && framesize <= map.size) {
672 res = gst_base_parse_finish_frame (parse, frame, framesize);
673 }
674
675 return res;
676 }
677
678
679 /*
680 * MPEG-PS private1 streams add a 2 bytes "Audio Substream Headers" for each
681 * buffer (not each frame) with the offset of the next frame's start.
682 *
683 * Buffer 1:
684 * -------------------------------------------
685 * |firstAccUnit|AC3SyncWord|xxxxxxxxxxxxxxxxx
686 * -------------------------------------------
687 * Buffer 2:
688 * -------------------------------------------
689 * |firstAccUnit|xxxxxx|AC3SyncWord|xxxxxxxxxx
690 * -------------------------------------------
691 *
692 * These 2 bytes can be dropped safely as they do not include any timing
693 * information, only the offset to the start of the next frame.
694 *
695 * From http://stnsoft.com/DVD/ass-hdr.html:
696 * "FirstAccUnit offset to frame which corresponds to PTS value offset 0 is the
697 * last byte of FirstAccUnit, ie add the offset of byte 2 to get the AU's offset
698 * The value 0000 indicates there is no first access unit"
699 * */
700
701 static GstFlowReturn
gst_ac3_parse_chain_priv(GstPad * pad,GstObject * parent,GstBuffer * buf)702 gst_ac3_parse_chain_priv (GstPad * pad, GstObject * parent, GstBuffer * buf)
703 {
704 GstAc3Parse *ac3parse = GST_AC3_PARSE (parent);
705 GstFlowReturn ret;
706 gsize size;
707 guint8 data[2];
708 gint offset;
709 gint len;
710 GstBuffer *subbuf;
711 gint first_access;
712
713 size = gst_buffer_get_size (buf);
714 if (size < 2)
715 goto not_enough_data;
716
717 gst_buffer_extract (buf, 0, data, 2);
718 first_access = (data[0] << 8) | data[1];
719
720 /* Skip the first_access header */
721 offset = 2;
722
723 if (first_access > 1) {
724 /* Length of data before first_access */
725 len = first_access - 1;
726
727 if (len <= 0 || offset + len > size)
728 goto bad_first_access_parameter;
729
730 subbuf = gst_buffer_copy_region (buf, GST_BUFFER_COPY_ALL, offset, len);
731 GST_BUFFER_DTS (subbuf) = GST_CLOCK_TIME_NONE;
732 GST_BUFFER_PTS (subbuf) = GST_CLOCK_TIME_NONE;
733 ret = ac3parse->baseparse_chainfunc (pad, parent, subbuf);
734 if (ret != GST_FLOW_OK && ret != GST_FLOW_NOT_LINKED) {
735 gst_buffer_unref (buf);
736 goto done;
737 }
738
739 offset += len;
740 len = size - offset;
741
742 if (len > 0) {
743 subbuf = gst_buffer_copy_region (buf, GST_BUFFER_COPY_ALL, offset, len);
744 GST_BUFFER_PTS (subbuf) = GST_BUFFER_PTS (buf);
745 GST_BUFFER_DTS (subbuf) = GST_BUFFER_DTS (buf);
746
747 ret = ac3parse->baseparse_chainfunc (pad, parent, subbuf);
748 }
749 gst_buffer_unref (buf);
750 } else {
751 /* first_access = 0 or 1, so if there's a timestamp it applies to the first byte */
752 subbuf =
753 gst_buffer_copy_region (buf, GST_BUFFER_COPY_ALL, offset,
754 size - offset);
755 GST_BUFFER_PTS (subbuf) = GST_BUFFER_PTS (buf);
756 GST_BUFFER_DTS (subbuf) = GST_BUFFER_DTS (buf);
757 gst_buffer_unref (buf);
758 ret = ac3parse->baseparse_chainfunc (pad, parent, subbuf);
759 }
760
761 done:
762 return ret;
763
764 /* ERRORS */
765 not_enough_data:
766 {
767 GST_ELEMENT_ERROR (GST_ELEMENT (ac3parse), STREAM, FORMAT, (NULL),
768 ("Insufficient data in buffer. Can't determine first_acess"));
769 gst_buffer_unref (buf);
770 return GST_FLOW_ERROR;
771 }
772 bad_first_access_parameter:
773 {
774 GST_ELEMENT_ERROR (GST_ELEMENT (ac3parse), STREAM, FORMAT, (NULL),
775 ("Bad first_access parameter (%d) in buffer", first_access));
776 gst_buffer_unref (buf);
777 return GST_FLOW_ERROR;
778 }
779 }
780
781 static GstFlowReturn
gst_ac3_parse_pre_push_frame(GstBaseParse * parse,GstBaseParseFrame * frame)782 gst_ac3_parse_pre_push_frame (GstBaseParse * parse, GstBaseParseFrame * frame)
783 {
784 GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
785
786 if (!ac3parse->sent_codec_tag) {
787 GstTagList *taglist;
788 GstCaps *caps;
789
790 /* codec tag */
791 caps = gst_pad_get_current_caps (GST_BASE_PARSE_SRC_PAD (parse));
792 if (G_UNLIKELY (caps == NULL)) {
793 if (GST_PAD_IS_FLUSHING (GST_BASE_PARSE_SRC_PAD (parse))) {
794 GST_INFO_OBJECT (parse, "Src pad is flushing");
795 return GST_FLOW_FLUSHING;
796 } else {
797 GST_INFO_OBJECT (parse, "Src pad is not negotiated!");
798 return GST_FLOW_NOT_NEGOTIATED;
799 }
800 }
801
802 taglist = gst_tag_list_new_empty ();
803 gst_pb_utils_add_codec_description_to_tag_list (taglist,
804 GST_TAG_AUDIO_CODEC, caps);
805 gst_caps_unref (caps);
806
807 gst_base_parse_merge_tags (parse, taglist, GST_TAG_MERGE_REPLACE);
808 gst_tag_list_unref (taglist);
809
810 /* also signals the end of first-frame processing */
811 ac3parse->sent_codec_tag = TRUE;
812 }
813
814 frame->flags |= GST_BASE_PARSE_FRAME_FLAG_CLIP;
815
816 return GST_FLOW_OK;
817 }
818
819 static gboolean
gst_ac3_parse_src_event(GstBaseParse * parse,GstEvent * event)820 gst_ac3_parse_src_event (GstBaseParse * parse, GstEvent * event)
821 {
822 GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
823
824 if (G_UNLIKELY (GST_EVENT_TYPE (event) == GST_EVENT_CUSTOM_UPSTREAM) &&
825 gst_event_has_name (event, "ac3parse-set-alignment")) {
826 const GstStructure *st = gst_event_get_structure (event);
827 const gchar *align = gst_structure_get_string (st, "alignment");
828
829 if (g_str_equal (align, "iec61937")) {
830 GST_DEBUG_OBJECT (ac3parse, "Switching to iec61937 alignment");
831 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_IEC61937);
832 } else if (g_str_equal (align, "frame")) {
833 GST_DEBUG_OBJECT (ac3parse, "Switching to frame alignment");
834 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_FRAME);
835 } else {
836 g_atomic_int_set (&ac3parse->align, GST_AC3_PARSE_ALIGN_FRAME);
837 GST_WARNING_OBJECT (ac3parse, "Got unknown alignment request (%s) "
838 "reverting to frame alignment.",
839 gst_structure_get_string (st, "alignment"));
840 }
841
842 gst_event_unref (event);
843 return TRUE;
844 }
845
846 return GST_BASE_PARSE_CLASS (parent_class)->src_event (parse, event);
847 }
848
849 static void
remove_fields(GstCaps * caps)850 remove_fields (GstCaps * caps)
851 {
852 guint i, n;
853
854 n = gst_caps_get_size (caps);
855 for (i = 0; i < n; i++) {
856 GstStructure *s = gst_caps_get_structure (caps, i);
857
858 gst_structure_remove_field (s, "framed");
859 gst_structure_remove_field (s, "alignment");
860 }
861 }
862
863 static GstCaps *
extend_caps(GstCaps * caps,gboolean add_private)864 extend_caps (GstCaps * caps, gboolean add_private)
865 {
866 guint i, n;
867 GstCaps *ncaps = gst_caps_new_empty ();
868
869 n = gst_caps_get_size (caps);
870 for (i = 0; i < n; i++) {
871 GstStructure *s = gst_caps_get_structure (caps, i);
872
873 if (add_private && !gst_structure_has_name (s, "audio/x-private1-ac3")) {
874 GstStructure *ns = gst_structure_copy (s);
875 gst_structure_set_name (ns, "audio/x-private1-ac3");
876 gst_caps_append_structure (ncaps, ns);
877 } else if (!add_private &&
878 gst_structure_has_name (s, "audio/x-private1-ac3")) {
879 GstStructure *ns = gst_structure_copy (s);
880 gst_structure_set_name (ns, "audio/x-ac3");
881 gst_caps_append_structure (ncaps, ns);
882 ns = gst_structure_copy (s);
883 gst_structure_set_name (ns, "audio/x-eac3");
884 gst_caps_append_structure (ncaps, ns);
885 } else if (!add_private) {
886 gst_caps_append_structure (ncaps, gst_structure_copy (s));
887 }
888 }
889
890 if (add_private) {
891 gst_caps_append (caps, ncaps);
892 } else {
893 gst_caps_unref (caps);
894 caps = ncaps;
895 }
896
897 return caps;
898 }
899
900 static GstCaps *
gst_ac3_parse_get_sink_caps(GstBaseParse * parse,GstCaps * filter)901 gst_ac3_parse_get_sink_caps (GstBaseParse * parse, GstCaps * filter)
902 {
903 GstCaps *peercaps, *templ;
904 GstCaps *res;
905
906 templ = gst_pad_get_pad_template_caps (GST_BASE_PARSE_SINK_PAD (parse));
907 if (filter) {
908 GstCaps *fcopy = gst_caps_copy (filter);
909 /* Remove the fields we convert */
910 remove_fields (fcopy);
911 /* we do not ask downstream to handle x-private1-ac3 */
912 fcopy = extend_caps (fcopy, FALSE);
913 peercaps = gst_pad_peer_query_caps (GST_BASE_PARSE_SRC_PAD (parse), fcopy);
914 gst_caps_unref (fcopy);
915 } else
916 peercaps = gst_pad_peer_query_caps (GST_BASE_PARSE_SRC_PAD (parse), NULL);
917
918 if (peercaps) {
919 /* Remove the framed and alignment field. We can convert
920 * between different alignments. */
921 peercaps = gst_caps_make_writable (peercaps);
922 remove_fields (peercaps);
923 /* also allow for x-private1-ac3 input */
924 peercaps = extend_caps (peercaps, TRUE);
925
926 res = gst_caps_intersect_full (peercaps, templ, GST_CAPS_INTERSECT_FIRST);
927 gst_caps_unref (peercaps);
928 gst_caps_unref (templ);
929 } else {
930 res = templ;
931 }
932
933 if (filter) {
934 GstCaps *intersection;
935
936 intersection =
937 gst_caps_intersect_full (filter, res, GST_CAPS_INTERSECT_FIRST);
938 gst_caps_unref (res);
939 res = intersection;
940 }
941
942 return res;
943 }
944
945 static gboolean
gst_ac3_parse_set_sink_caps(GstBaseParse * parse,GstCaps * caps)946 gst_ac3_parse_set_sink_caps (GstBaseParse * parse, GstCaps * caps)
947 {
948 GstStructure *s;
949 GstAc3Parse *ac3parse = GST_AC3_PARSE (parse);
950
951 s = gst_caps_get_structure (caps, 0);
952 if (gst_structure_has_name (s, "audio/x-private1-ac3")) {
953 gst_pad_set_chain_function (parse->sinkpad, gst_ac3_parse_chain_priv);
954 } else {
955 gst_pad_set_chain_function (parse->sinkpad, ac3parse->baseparse_chainfunc);
956 }
957 return TRUE;
958 }
959