FFmpeg: libavformat/movenchint.c Source File

FFmpeg

[フレーム]

libavformat

movenchint.c

Go to the documentation of this file.

1 /*

2 * MOV, 3GP, MP4 muxer RTP hinting

4 *

5 * This file is part of FFmpeg.

6 *

7 * FFmpeg is free software; you can redistribute it and/or

8 * modify it under the terms of the GNU Lesser General Public

9 * License as published by the Free Software Foundation; either

10 * version 2.1 of the License, or (at your option) any later version.

11 *

12 * FFmpeg 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 * Lesser General Public License for more details.

16 *

17 * You should have received a copy of the GNU Lesser General Public

18 * License along with FFmpeg; if not, write to the Free Software

19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

20 */

22 #include "movenc.h"

23 #include "libavutil/intreadwrite.h"

24 #include "internal.h"

25 #include "rtpenc_chain.h"

26 #include "avio_internal.h"

27 #include "rtp.h"

29 int ff_mov_init_hinting(AVFormatContext *s, int index, int src_index)

30 {

31 MOVMuxContext *mov = s->priv_data;

32 MOVTrack *track = &mov->tracks[index];

33 MOVTrack *src_track = &mov->tracks[src_index];

34 AVStream *src_st = s->streams[src_index];

35 int ret = AVERROR(ENOMEM);

37 track->tag = MKTAG('r','t','p',' ');

38 track->src_track = src_index;

40 track->enc = avcodec_alloc_context3(NULL);

41 if (!track->enc)

42 goto fail;

43 track->enc->codec_type = AVMEDIA_TYPE_DATA;

44 track->enc->codec_tag = track->tag;

46 ret = ff_rtp_chain_mux_open(&track->rtp_ctx, s, src_st, NULL,

47 RTP_MAX_PACKET_SIZE, src_index);

48 if (ret < 0)

49 goto fail;

51 /* Copy the RTP AVStream timebase back to the hint AVStream */

52 track->timescale = track->rtp_ctx->streams[0]->time_base.den;

54 /* Mark the hinted track that packets written to it should be

55 * sent to this track for hinting. */

56 src_track->hint_track = index;

57 return 0;

58 fail:

59 av_log(s, AV_LOG_WARNING,

60 "Unable to initialize hinting of stream %d\n", src_index);

61 av_freep(&track->enc);

62 /* Set a default timescale, to avoid crashes in av_dump_format */

63 track->timescale = 90000;

64 return ret;

65 }

67 /**

68 * Remove the first sample from the sample queue.

69 */

70 static void sample_queue_pop(HintSampleQueue *queue)

71 {

72 if (queue->len <= 0)

73 return;

74 if (queue->samples[0].own_data)

75 av_freep(&queue->samples[0].data);

76 queue->len--;

77 memmove(queue->samples, queue->samples + 1, sizeof(HintSample)*queue->len);

78 }

80 /**

81 * Empty the sample queue, releasing all memory.

82 */

83 static void sample_queue_free(HintSampleQueue *queue)

84 {

85 int i;

86 for (i = 0; i < queue->len; i++)

87 if (queue->samples[i].own_data)

88 av_freep(&queue->samples[i].data);

89 av_freep(&queue->samples);

90 queue->len = 0;

91 queue->size = 0;

92 }

94 /**

95 * Add a reference to the sample data to the sample queue. The data is

96 * not copied. sample_queue_retain should be called before pkt->data

97 * is reused/freed.

98 */

99 static void sample_queue_push(HintSampleQueue *queue, uint8_t *data, int size,

100 int sample)

101 {

102 /* No need to keep track of smaller samples, since describing them

103 * with immediates is more efficient. */

104 if (size <= 14)

105 return;

106 if (!queue->samples || queue->len >= queue->size) {

107 HintSample *samples;

108 samples = av_realloc_array(queue->samples, queue->size + 10, sizeof(HintSample));

109 if (!samples)

110 return;

111 queue->size += 10;

112 queue->samples = samples;

113 }

114 queue->samples[queue->len].data = data;

115 queue->samples[queue->len].size = size;

116 queue->samples[queue->len].sample_number = sample;

117 queue->samples[queue->len].offset = 0;

118 queue->samples[queue->len].own_data = 0;

119 queue->len++;

120 }

121

122 /**

123 * Make local copies of all referenced sample data in the queue.

124 */

125 static void sample_queue_retain(HintSampleQueue *queue)

126 {

127 int i;

128 for (i = 0; i < queue->len; ) {

129 HintSample *sample = &queue->samples[i];

130 if (!sample->own_data) {

131 uint8_t *ptr = av_malloc(sample->size);

132 if (!ptr) {

133 /* Unable to allocate memory for this one, remove it */

134 memmove(queue->samples + i, queue->samples + i + 1,

135 sizeof(HintSample)*(queue->len - i - 1));

136 queue->len--;

137 continue;

138 }

139 memcpy(ptr, sample->data, sample->size);

140 sample->data = ptr;

141 sample->own_data = 1;

142 }

143 i++;

144 }

145 }

146

147 /**

148 * Find matches of needle[n_pos ->] within haystack. If a sufficiently

149 * large match is found, matching bytes before n_pos are included

150 * in the match, too (within the limits of the arrays).

151 *

152 * @param haystack buffer that may contain parts of needle

153 * @param h_len length of the haystack buffer

154 * @param needle buffer containing source data that have been used to

155 * construct haystack

156 * @param n_pos start position in needle used for looking for matches

157 * @param n_len length of the needle buffer

158 * @param match_h_offset_ptr offset of the first matching byte within haystack

159 * @param match_n_offset_ptr offset of the first matching byte within needle

160 * @param match_len_ptr length of the matched segment

161 * @return 0 if a match was found, < 0 if no match was found

162 */

163 static int match_segments(const uint8_t *haystack, int h_len,

164 const uint8_t *needle, int n_pos, int n_len,

165 int *match_h_offset_ptr, int *match_n_offset_ptr,

166 int *match_len_ptr)

167 {

168 int h_pos;

169 for (h_pos = 0; h_pos < h_len; h_pos++) {

170 int match_len = 0;

171 int match_h_pos, match_n_pos;

172

173 /* Check how many bytes match at needle[n_pos] and haystack[h_pos] */

174 while (h_pos + match_len < h_len && n_pos + match_len < n_len &&

175 needle[n_pos + match_len] == haystack[h_pos + match_len])

176 match_len++;

177 if (match_len <= 8)

178 continue;

179

180 /* If a sufficiently large match was found, try to expand

181 * the matched segment backwards. */

182 match_h_pos = h_pos;

183 match_n_pos = n_pos;

184 while (match_n_pos > 0 && match_h_pos > 0 &&

185 needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {

186 match_n_pos--;

187 match_h_pos--;

188 match_len++;

189 }

190 if (match_len <= 14)

191 continue;

192 *match_h_offset_ptr = match_h_pos;

193 *match_n_offset_ptr = match_n_pos;

194 *match_len_ptr = match_len;

195 return 0;

196 }

197 return -1;

198 }

199

200 /**

201 * Look for segments in samples in the sample queue matching the data

202 * in ptr. Samples not matching are removed from the queue. If a match

203 * is found, the next time it will look for matches starting from the

204 * end of the previous matched segment.

205 *

206 * @param data data to find matches for in the sample queue

207 * @param len length of the data buffer

208 * @param queue samples used for looking for matching segments

209 * @param pos the offset in data of the matched segment

210 * @param match_sample the number of the sample that contained the match

211 * @param match_offset the offset of the matched segment within the sample

212 * @param match_len the length of the matched segment

213 * @return 0 if a match was found, < 0 if no match was found

214 */

215 static int find_sample_match(const uint8_t *data, int len,

216 HintSampleQueue *queue, int *pos,

217 int *match_sample, int *match_offset,

218 int *match_len)

219 {

220 while (queue->len > 0) {

221 HintSample *sample = &queue->samples[0];

222 /* If looking for matches in a new sample, skip the first 5 bytes,

223 * since they often may be modified/removed in the output packet. */

224 if (sample->offset == 0 && sample->size > 5)

225 sample->offset = 5;

226

227 if (match_segments(data, len, sample->data, sample->offset,

228 sample->size, pos, match_offset, match_len) == 0) {

229 *match_sample = sample->sample_number;

230 /* Next time, look for matches at this offset, with a little

231 * margin to this match. */

232 sample->offset = *match_offset + *match_len + 5;

233 if (sample->offset + 10 >= sample->size)

234 sample_queue_pop(queue); /* Not enough useful data left */

235 return 0;

236 }

237

238 if (sample->offset < 10 && sample->size > 20) {

239 /* No match found from the start of the sample,

240 * try from the middle of the sample instead. */

241 sample->offset = sample->size/2;

242 } else {

243 /* No match for this sample, remove it */

244 sample_queue_pop(queue);

245 }

246 }

247 return -1;

248 }

249

250 static void output_immediate(const uint8_t *data, int size,

251 AVIOContext *out, int *entries)

252 {

253 while (size > 0) {

254 int len = size;

255 if (len > 14)

256 len = 14;

257 avio_w8(out, 1); /* immediate constructor */

258 avio_w8(out, len); /* amount of valid data */

259 avio_write(out, data, len);

260 data += len;

261 size -= len;

262

263 for (; len < 14; len++)

264 avio_w8(out, 0);

265

266 (*entries)++;

267 }

268 }

269

270 static void output_match(AVIOContext *out, int match_sample,

271 int match_offset, int match_len, int *entries)

272 {

273 avio_w8(out, 2); /* sample constructor */

274 avio_w8(out, 0); /* track reference */

275 avio_wb16(out, match_len);

276 avio_wb32(out, match_sample);

277 avio_wb32(out, match_offset);

278 avio_wb16(out, 1); /* bytes per block */

279 avio_wb16(out, 1); /* samples per block */

280 (*entries)++;

281 }

282

283 static void describe_payload(const uint8_t *data, int size,

284 AVIOContext *out, int *entries,

285 HintSampleQueue *queue)

286 {

287 /* Describe the payload using different constructors */

288 while (size > 0) {

289 int match_sample, match_offset, match_len, pos;

290 if (find_sample_match(data, size, queue, &pos, &match_sample,

291 &match_offset, &match_len) < 0)

292 break;

293 output_immediate(data, pos, out, entries);

294 data += pos;

295 size -= pos;

296 output_match(out, match_sample, match_offset, match_len, entries);

297 data += match_len;

298 size -= match_len;

299 }

300 output_immediate(data, size, out, entries);

301 }

302

303 /**

304 * Write an RTP hint (that may contain one or more RTP packets)

305 * for the packets in data. data contains one or more packets with a

306 * BE32 size header.

307 *

308 * @param out buffer where the hints are written

309 * @param data buffer containing RTP packets

310 * @param size the size of the data buffer

311 * @param trk the MOVTrack for the hint track

312 * @param dts pointer where the timestamp for the written RTP hint is stored

313 * @return the number of RTP packets in the written hint

314 */

315 static int write_hint_packets(AVIOContext *out, const uint8_t *data,

316 int size, MOVTrack *trk, int64_t *dts)

317 {

318 int64_t curpos;

319 int64_t count_pos, entries_pos;

320 int count = 0, entries;

321

322 count_pos = avio_tell(out);

323 /* RTPsample header */

324 avio_wb16(out, 0); /* packet count */

325 avio_wb16(out, 0); /* reserved */

326

327 while (size > 4) {

328 uint32_t packet_len = AV_RB32(data);

329 uint16_t seq;

330 uint32_t ts;

331 int32_t ts_diff;

332

333 data += 4;

334 size -= 4;

335 if (packet_len > size || packet_len <= 12)

336 break;

337 if (RTP_PT_IS_RTCP(data[1])) {

338 /* RTCP packet, just skip */

339 data += packet_len;

340 size -= packet_len;

341 continue;

342 }

343

344 if (packet_len > trk->max_packet_size)

345 trk->max_packet_size = packet_len;

346

347 seq = AV_RB16(&data[2]);

348 ts = AV_RB32(&data[4]);

349

350 if (trk->prev_rtp_ts == 0)

351 trk->prev_rtp_ts = ts;

352 /* Unwrap the 32-bit RTP timestamp that wraps around often

353 * into a not (as often) wrapping 64-bit timestamp. */

354 ts_diff = ts - trk->prev_rtp_ts;

355 if (ts_diff > 0) {

356 trk->cur_rtp_ts_unwrapped += ts_diff;

357 trk->prev_rtp_ts = ts;

358 ts_diff = 0;

359 }

360 if (*dts == AV_NOPTS_VALUE)

361 *dts = trk->cur_rtp_ts_unwrapped;

362

363 count++;

364 /* RTPpacket header */

365 avio_wb32(out, 0); /* relative_time */

366 avio_write(out, data, 2); /* RTP header */

367 avio_wb16(out, seq); /* RTPsequenceseed */

368 avio_wb16(out, ts_diff ? 4 : 0); /* reserved + flags (extra_flag) */

369 entries_pos = avio_tell(out);

370 avio_wb16(out, 0); /* entry count */

371 if (ts_diff) { /* if extra_flag is set */

372 avio_wb32(out, 16); /* extra_information_length */

373 avio_wb32(out, 12); /* rtpoffsetTLV box */

374 avio_write(out, "rtpo", 4);

375 avio_wb32(out, ts_diff);

376 }

377

378 data += 12;

379 size -= 12;

380 packet_len -= 12;

381

382 entries = 0;

383 /* Write one or more constructors describing the payload data */

384 describe_payload(data, packet_len, out, &entries, &trk->sample_queue);

385 data += packet_len;

386 size -= packet_len;

387

388 curpos = avio_tell(out);

389 avio_seek(out, entries_pos, SEEK_SET);

390 avio_wb16(out, entries);

391 avio_seek(out, curpos, SEEK_SET);

392 }

393

394 curpos = avio_tell(out);

395 avio_seek(out, count_pos, SEEK_SET);

396 avio_wb16(out, count);

397 avio_seek(out, curpos, SEEK_SET);

398 return count;

399 }

400

401 int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,

402 int track_index, int sample,

403 uint8_t *sample_data, int sample_size)

404 {

405 MOVMuxContext *mov = s->priv_data;

406 MOVTrack *trk = &mov->tracks[track_index];

407 AVFormatContext *rtp_ctx = trk->rtp_ctx;

408 uint8_t *buf = NULL;

409 int size;

410 AVIOContext *hintbuf = NULL;

411 AVPacket hint_pkt;

412 int ret = 0, count;

413

414 if (!rtp_ctx)

415 return AVERROR(ENOENT);

416 if (!rtp_ctx->pb)

417 return AVERROR(ENOMEM);

418

419 if (sample_data)

420 sample_queue_push(&trk->sample_queue, sample_data, sample_size, sample);

421 else

422 sample_queue_push(&trk->sample_queue, pkt->data, pkt->size, sample);

423

424 /* Feed the packet to the RTP muxer */

425 ff_write_chained(rtp_ctx, 0, pkt, s, 0);

426

427 /* Fetch the output from the RTP muxer, open a new output buffer

428 * for next time. */

429 size = avio_close_dyn_buf(rtp_ctx->pb, &buf);

430 if ((ret = ffio_open_dyn_packet_buf(&rtp_ctx->pb,

431 RTP_MAX_PACKET_SIZE)) < 0)

432 goto done;

433

434 if (size <= 0)

435 goto done;

436

437 /* Open a buffer for writing the hint */

438 if ((ret = avio_open_dyn_buf(&hintbuf)) < 0)

439 goto done;

440 av_init_packet(&hint_pkt);

441 count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);

442 av_freep(&buf);

443

444 /* Write the hint data into the hint track */

445 hint_pkt.size = size = avio_close_dyn_buf(hintbuf, &buf);

446 hint_pkt.data = buf;

447 hint_pkt.pts = hint_pkt.dts;

448 hint_pkt.stream_index = track_index;

449 if (pkt->flags & AV_PKT_FLAG_KEY)

450 hint_pkt.flags |= AV_PKT_FLAG_KEY;

451 if (count > 0)

452 ff_mov_write_packet(s, &hint_pkt);

453 done:

454 av_free(buf);

455 sample_queue_retain(&trk->sample_queue);

456 return ret;

457 }

458

459 void ff_mov_close_hinting(MOVTrack *track)

460 {

461 AVFormatContext *rtp_ctx = track->rtp_ctx;

462

463 av_freep(&track->enc);

464 sample_queue_free(&track->sample_queue);

465 if (!rtp_ctx)

466 return;

467 if (rtp_ctx->pb) {

468 av_write_trailer(rtp_ctx);

469 ffio_free_dyn_buf(&rtp_ctx->pb);

470 }

471 avformat_free_context(rtp_ctx);

472 }

Generated on Sun Mar 8 2015 02:35:10 for FFmpeg by doxygen 1.8.2