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muxing.c

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1 /*

3 *

4 * Permission is hereby granted, free of charge, to any person obtaining a copy

5 * of this software and associated documentation files (the "Software"), to deal

6 * in the Software without restriction, including without limitation the rights

7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

8 * copies of the Software, and to permit persons to whom the Software is

9 * furnished to do so, subject to the following conditions:

10 *

11 * The above copyright notice and this permission notice shall be included in

12 * all copies or substantial portions of the Software.

13 *

14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

17 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

20 * THE SOFTWARE.

21 */

23 /**

24 * @file

25 * libavformat API example.

26 *

27 * Output a media file in any supported libavformat format. The default

28 * codecs are used.

29 * @example muxing.c

30 */

32 #include <stdlib.h>

33 #include <stdio.h>

34 #include <string.h>

35 #include <math.h>

37 #include <libavutil/avassert.h>

38 #include <libavutil/channel_layout.h>

39 #include <libavutil/opt.h>

40 #include <libavutil/mathematics.h>

41 #include <libavutil/timestamp.h>

42 #include <libavformat/avformat.h>

43 #include <libswscale/swscale.h>

44 #include <libswresample/swresample.h>

46 #define STREAM_DURATION 10.0

47 #define STREAM_FRAME_RATE 25 /* 25 images/s */

48 #define STREAM_PIX_FMT AV_PIX_FMT_YUV420P /* default pix_fmt */

50 #define SCALE_FLAGS SWS_BICUBIC

52 // a wrapper around a single output AVStream

53 typedef struct OutputStream {

54 AVStream *st;

56 /* pts of the next frame that will be generated */

57 int64_t next_pts;

58 int samples_count;

60 AVFrame *frame;

61 AVFrame *tmp_frame;

63 float t, tincr, tincr2;

65 struct SwsContext *sws_ctx;

66 struct SwrContext *swr_ctx;

67 } OutputStream;

69 static void log_packet(const AVFormatContext *fmt_ctx, const AVPacket *pkt)

70 {

71 AVRational *time_base = &fmt_ctx->streams[pkt->stream_index]->time_base;

73 printf("pts:%s pts_time:%s dts:%s dts_time:%s duration:%s duration_time:%s stream_index:%d\n",

74 av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, time_base),

75 av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, time_base),

76 av_ts2str(pkt->duration), av_ts2timestr(pkt->duration, time_base),

77 pkt->stream_index);

78 }

80 static int write_frame(AVFormatContext *fmt_ctx, const AVRational *time_base, AVStream *st, AVPacket *pkt)

81 {

82 /* rescale output packet timestamp values from codec to stream timebase */

83 av_packet_rescale_ts(pkt, *time_base, st->time_base);

84 pkt->stream_index = st->index;

86 /* Write the compressed frame to the media file. */

87 log_packet(fmt_ctx, pkt);

88 return av_interleaved_write_frame(fmt_ctx, pkt);

89 }

91 /* Add an output stream. */

92 static void add_stream(OutputStream *ost, AVFormatContext *oc,

93 AVCodec **codec,

94 enum AVCodecID codec_id)

95 {

96 AVCodecContext *c;

97 int i;

99 /* find the encoder */

100 *codec = avcodec_find_encoder(codec_id);

101 if (!(*codec)) {

102 fprintf(stderr, "Could not find encoder for '%s'\n",

103 avcodec_get_name(codec_id));

104 exit(1);

105 }

106

107 ost->st = avformat_new_stream(oc, *codec);

108 if (!ost->st) {

109 fprintf(stderr, "Could not allocate stream\n");

110 exit(1);

111 }

112 ost->st->id = oc->nb_streams-1;

113 c = ost->st->codec;

114

115 switch ((*codec)->type) {

116 case AVMEDIA_TYPE_AUDIO:

117 c->sample_fmt = (*codec)->sample_fmts ?

118 (*codec)->sample_fmts[0] : AV_SAMPLE_FMT_FLTP;

119 c->bit_rate = 64000;

120 c->sample_rate = 44100;

121 if ((*codec)->supported_samplerates) {

122 c->sample_rate = (*codec)->supported_samplerates[0];

123 for (i = 0; (*codec)->supported_samplerates[i]; i++) {

124 if ((*codec)->supported_samplerates[i] == 44100)

125 c->sample_rate = 44100;

126 }

127 }

128 c->channels = av_get_channel_layout_nb_channels(c->channel_layout);

129 c->channel_layout = AV_CH_LAYOUT_STEREO;

130 if ((*codec)->channel_layouts) {

131 c->channel_layout = (*codec)->channel_layouts[0];

132 for (i = 0; (*codec)->channel_layouts[i]; i++) {

133 if ((*codec)->channel_layouts[i] == AV_CH_LAYOUT_STEREO)

134 c->channel_layout = AV_CH_LAYOUT_STEREO;

135 }

136 }

137 c->channels = av_get_channel_layout_nb_channels(c->channel_layout);

138 ost->st->time_base = (AVRational){ 1, c->sample_rate };

139 break;

140

141 case AVMEDIA_TYPE_VIDEO:

142 c->codec_id = codec_id;

143

144 c->bit_rate = 400000;

145 /* Resolution must be a multiple of two. */

146 c->width = 352;

147 c->height = 288;

148 /* timebase: This is the fundamental unit of time (in seconds) in terms

149 * of which frame timestamps are represented. For fixed-fps content,

150 * timebase should be 1/framerate and timestamp increments should be

151 * identical to 1. */

152 ost->st->time_base = (AVRational){ 1, STREAM_FRAME_RATE };

153 c->time_base = ost->st->time_base;

154

155 c->gop_size = 12; /* emit one intra frame every twelve frames at most */

156 c->pix_fmt = STREAM_PIX_FMT;

157 if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO) {

158 /* just for testing, we also add B frames */

159 c->max_b_frames = 2;

160 }

161 if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO) {

162 /* Needed to avoid using macroblocks in which some coeffs overflow.

163 * This does not happen with normal video, it just happens here as

164 * the motion of the chroma plane does not match the luma plane. */

165 c->mb_decision = 2;

166 }

167 break;

168

169 default:

170 break;

171 }

172

173 /* Some formats want stream headers to be separate. */

174 if (oc->oformat->flags & AVFMT_GLOBALHEADER)

175 c->flags |= CODEC_FLAG_GLOBAL_HEADER;

176 }

177

178 /**************************************************************/

179 /* audio output */

180

181 static AVFrame *alloc_audio_frame(enum AVSampleFormat sample_fmt,

182 uint64_t channel_layout,

183 int sample_rate, int nb_samples)

184 {

185 AVFrame *frame = av_frame_alloc();

186 int ret;

187

188 if (!frame) {

189 fprintf(stderr, "Error allocating an audio frame\n");

190 exit(1);

191 }

192

193 frame->format = sample_fmt;

194 frame->channel_layout = channel_layout;

195 frame->sample_rate = sample_rate;

196 frame->nb_samples = nb_samples;

197

198 if (nb_samples) {

199 ret = av_frame_get_buffer(frame, 0);

200 if (ret < 0) {

201 fprintf(stderr, "Error allocating an audio buffer\n");

202 exit(1);

203 }

204 }

205

206 return frame;

207 }

208

209 static void open_audio(AVFormatContext *oc, AVCodec *codec, OutputStream *ost, AVDictionary *opt_arg)

210 {

211 AVCodecContext *c;

212 int nb_samples;

213 int ret;

214 AVDictionary *opt = NULL;

215

216 c = ost->st->codec;

217

218 /* open it */

219 av_dict_copy(&opt, opt_arg, 0);

220 ret = avcodec_open2(c, codec, &opt);

221 av_dict_free(&opt);

222 if (ret < 0) {

223 fprintf(stderr, "Could not open audio codec: %s\n", av_err2str(ret));

224 exit(1);

225 }

226

227 /* init signal generator */

228 ost->t = 0;

229 ost->tincr = 2 * M_PI * 110.0 / c->sample_rate;

230 /* increment frequency by 110 Hz per second */

231 ost->tincr2 = 2 * M_PI * 110.0 / c->sample_rate / c->sample_rate;

232

233 if (c->codec->capabilities & CODEC_CAP_VARIABLE_FRAME_SIZE)

234 nb_samples = 10000;

235 else

236 nb_samples = c->frame_size;

237

238 ost->frame = alloc_audio_frame(c->sample_fmt, c->channel_layout,

239 c->sample_rate, nb_samples);

240 ost->tmp_frame = alloc_audio_frame(AV_SAMPLE_FMT_S16, c->channel_layout,

241 c->sample_rate, nb_samples);

242

243 /* create resampler context */

244 ost->swr_ctx = swr_alloc();

245 if (!ost->swr_ctx) {

246 fprintf(stderr, "Could not allocate resampler context\n");

247 exit(1);

248 }

249

250 /* set options */

251 av_opt_set_int (ost->swr_ctx, "in_channel_count", c->channels, 0);

252 av_opt_set_int (ost->swr_ctx, "in_sample_rate", c->sample_rate, 0);

253 av_opt_set_sample_fmt(ost->swr_ctx, "in_sample_fmt", AV_SAMPLE_FMT_S16, 0);

254 av_opt_set_int (ost->swr_ctx, "out_channel_count", c->channels, 0);

255 av_opt_set_int (ost->swr_ctx, "out_sample_rate", c->sample_rate, 0);

256 av_opt_set_sample_fmt(ost->swr_ctx, "out_sample_fmt", c->sample_fmt, 0);

257

258 /* initialize the resampling context */

259 if ((ret = swr_init(ost->swr_ctx)) < 0) {

260 fprintf(stderr, "Failed to initialize the resampling context\n");

261 exit(1);

262 }

263 }

264

265 /* Prepare a 16 bit dummy audio frame of 'frame_size' samples and

266 * 'nb_channels' channels. */

267 static AVFrame *get_audio_frame(OutputStream *ost)

268 {

269 AVFrame *frame = ost->tmp_frame;

270 int j, i, v;

271 int16_t *q = (int16_t*)frame->data[0];

272

273 /* check if we want to generate more frames */

274 if (av_compare_ts(ost->next_pts, ost->st->codec->time_base,

275 STREAM_DURATION, (AVRational){ 1, 1 }) >= 0)

276 return NULL;

277

278 for (j = 0; j <frame->nb_samples; j++) {

279 v = (int)(sin(ost->t) * 10000);

280 for (i = 0; i < ost->st->codec->channels; i++)

281 *q++ = v;

282 ost->t += ost->tincr;

283 ost->tincr += ost->tincr2;

284 }

285

286 frame->pts = ost->next_pts;

287 ost->next_pts += frame->nb_samples;

288

289 return frame;

290 }

291

292 /*

293 * encode one audio frame and send it to the muxer

294 * return 1 when encoding is finished, 0 otherwise

295 */

296 static int write_audio_frame(AVFormatContext *oc, OutputStream *ost)

297 {

298 AVCodecContext *c;

299 AVPacket pkt = { 0 }; // data and size must be 0;

300 AVFrame *frame;

301 int ret;

302 int got_packet;

303 int dst_nb_samples;

304

305 av_init_packet(&pkt);

306 c = ost->st->codec;

307

308 frame = get_audio_frame(ost);

309

310 if (frame) {

311 /* convert samples from native format to destination codec format, using the resampler */

312 /* compute destination number of samples */

313 dst_nb_samples = av_rescale_rnd(swr_get_delay(ost->swr_ctx, c->sample_rate) + frame->nb_samples,

314 c->sample_rate, c->sample_rate, AV_ROUND_UP);

315 av_assert0(dst_nb_samples == frame->nb_samples);

316

317 /* when we pass a frame to the encoder, it may keep a reference to it

318 * internally;

319 * make sure we do not overwrite it here

320 */

321 ret = av_frame_make_writable(ost->frame);

322 if (ret < 0)

323 exit(1);

324

325 /* convert to destination format */

326 ret = swr_convert(ost->swr_ctx,

327 ost->frame->data, dst_nb_samples,

328 (const uint8_t **)frame->data, frame->nb_samples);

329 if (ret < 0) {

330 fprintf(stderr, "Error while converting\n");

331 exit(1);

332 }

333 frame = ost->frame;

334

335 frame->pts = av_rescale_q(ost->samples_count, (AVRational){1, c->sample_rate}, c->time_base);

336 ost->samples_count += dst_nb_samples;

337 }

338

339 ret = avcodec_encode_audio2(c, &pkt, frame, &got_packet);

340 if (ret < 0) {

341 fprintf(stderr, "Error encoding audio frame: %s\n", av_err2str(ret));

342 exit(1);

343 }

344

345 if (got_packet) {

346 ret = write_frame(oc, &c->time_base, ost->st, &pkt);

347 if (ret < 0) {

348 fprintf(stderr, "Error while writing audio frame: %s\n",

349 av_err2str(ret));

350 exit(1);

351 }

352 }

353

354 return (frame || got_packet) ? 0 : 1;

355 }

356

357 /**************************************************************/

358 /* video output */

359

360 static AVFrame *alloc_picture(enum AVPixelFormat pix_fmt, int width, int height)

361 {

362 AVFrame *picture;

363 int ret;

364

365 picture = av_frame_alloc();

366 if (!picture)

367 return NULL;

368

369 picture->format = pix_fmt;

370 picture->width = width;

371 picture->height = height;

372

373 /* allocate the buffers for the frame data */

374 ret = av_frame_get_buffer(picture, 32);

375 if (ret < 0) {

376 fprintf(stderr, "Could not allocate frame data.\n");

377 exit(1);

378 }

379

380 return picture;

381 }

382

383 static void open_video(AVFormatContext *oc, AVCodec *codec, OutputStream *ost, AVDictionary *opt_arg)

384 {

385 int ret;

386 AVCodecContext *c = ost->st->codec;

387 AVDictionary *opt = NULL;

388

389 av_dict_copy(&opt, opt_arg, 0);

390

391 /* open the codec */

392 ret = avcodec_open2(c, codec, &opt);

393 av_dict_free(&opt);

394 if (ret < 0) {

395 fprintf(stderr, "Could not open video codec: %s\n", av_err2str(ret));

396 exit(1);

397 }

398

399 /* allocate and init a re-usable frame */

400 ost->frame = alloc_picture(c->pix_fmt, c->width, c->height);

401 if (!ost->frame) {

402 fprintf(stderr, "Could not allocate video frame\n");

403 exit(1);

404 }

405

406 /* If the output format is not YUV420P, then a temporary YUV420P

407 * picture is needed too. It is then converted to the required

408 * output format. */

409 ost->tmp_frame = NULL;

410 if (c->pix_fmt != AV_PIX_FMT_YUV420P) {

411 ost->tmp_frame = alloc_picture(AV_PIX_FMT_YUV420P, c->width, c->height);

412 if (!ost->tmp_frame) {

413 fprintf(stderr, "Could not allocate temporary picture\n");

414 exit(1);

415 }

416 }

417 }

418

419 /* Prepare a dummy image. */

420 static void fill_yuv_image(AVFrame *pict, int frame_index,

421 int width, int height)

422 {

423 int x, y, i, ret;

424

425 /* when we pass a frame to the encoder, it may keep a reference to it

426 * internally;

427 * make sure we do not overwrite it here

428 */

429 ret = av_frame_make_writable(pict);

430 if (ret < 0)

431 exit(1);

432

433 i = frame_index;

434

435 /* Y */

436 for (y = 0; y < height; y++)

437 for (x = 0; x < width; x++)

438 pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;

439

440 /* Cb and Cr */

441 for (y = 0; y < height / 2; y++) {

442 for (x = 0; x < width / 2; x++) {

443 pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;

444 pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;

445 }

446 }

447 }

448

449 static AVFrame *get_video_frame(OutputStream *ost)

450 {

451 AVCodecContext *c = ost->st->codec;

452

453 /* check if we want to generate more frames */

454 if (av_compare_ts(ost->next_pts, ost->st->codec->time_base,

455 STREAM_DURATION, (AVRational){ 1, 1 }) >= 0)

456 return NULL;

457

458 if (c->pix_fmt != AV_PIX_FMT_YUV420P) {

459 /* as we only generate a YUV420P picture, we must convert it

460 * to the codec pixel format if needed */

461 if (!ost->sws_ctx) {

462 ost->sws_ctx = sws_getContext(c->width, c->height,

463 AV_PIX_FMT_YUV420P,

464 c->width, c->height,

465 c->pix_fmt,

466 SCALE_FLAGS, NULL, NULL, NULL);

467 if (!ost->sws_ctx) {

468 fprintf(stderr,

469 "Could not initialize the conversion context\n");

470 exit(1);

471 }

472 }

473 fill_yuv_image(ost->tmp_frame, ost->next_pts, c->width, c->height);

474 sws_scale(ost->sws_ctx,

475 (const uint8_t * const *)ost->tmp_frame->data, ost->tmp_frame->linesize,

476 0, c->height, ost->frame->data, ost->frame->linesize);

477 } else {

478 fill_yuv_image(ost->frame, ost->next_pts, c->width, c->height);

479 }

480

481 ost->frame->pts = ost->next_pts++;

482

483 return ost->frame;

484 }

485

486 /*

487 * encode one video frame and send it to the muxer

488 * return 1 when encoding is finished, 0 otherwise

489 */

490 static int write_video_frame(AVFormatContext *oc, OutputStream *ost)

491 {

492 int ret;

493 AVCodecContext *c;

494 AVFrame *frame;

495 int got_packet = 0;

496

497 c = ost->st->codec;

498

499 frame = get_video_frame(ost);

500

501 if (oc->oformat->flags & AVFMT_RAWPICTURE) {

502 /* a hack to avoid data copy with some raw video muxers */

503 AVPacket pkt;

504 av_init_packet(&pkt);

505

506 if (!frame)

507 return 1;

508

509 pkt.flags |= AV_PKT_FLAG_KEY;

510 pkt.stream_index = ost->st->index;

511 pkt.data = (uint8_t *)frame;

512 pkt.size = sizeof(AVPicture);

513

514 pkt.pts = pkt.dts = frame->pts;

515 av_packet_rescale_ts(&pkt, c->time_base, ost->st->time_base);

516

517 ret = av_interleaved_write_frame(oc, &pkt);

518 } else {

519 AVPacket pkt = { 0 };

520 av_init_packet(&pkt);

521

522 /* encode the image */

523 ret = avcodec_encode_video2(c, &pkt, frame, &got_packet);

524 if (ret < 0) {

525 fprintf(stderr, "Error encoding video frame: %s\n", av_err2str(ret));

526 exit(1);

527 }

528

529 if (got_packet) {

530 ret = write_frame(oc, &c->time_base, ost->st, &pkt);

531 } else {

532 ret = 0;

533 }

534 }

535

536 if (ret < 0) {

537 fprintf(stderr, "Error while writing video frame: %s\n", av_err2str(ret));

538 exit(1);

539 }

540

541 return (frame || got_packet) ? 0 : 1;

542 }

543

544 static void close_stream(AVFormatContext *oc, OutputStream *ost)

545 {

546 avcodec_close(ost->st->codec);

547 av_frame_free(&ost->frame);

548 av_frame_free(&ost->tmp_frame);

549 sws_freeContext(ost->sws_ctx);

550 swr_free(&ost->swr_ctx);

551 }

552

553 /**************************************************************/

554 /* media file output */

555

556 int main(int argc, char **argv)

557 {

558 OutputStream video_st = { 0 }, audio_st = { 0 };

559 const char *filename;

560 AVOutputFormat *fmt;

561 AVFormatContext *oc;

562 AVCodec *audio_codec, *video_codec;

563 int ret;

564 int have_video = 0, have_audio = 0;

565 int encode_video = 0, encode_audio = 0;

566 AVDictionary *opt = NULL;

567

568 /* Initialize libavcodec, and register all codecs and formats. */

569 av_register_all();

570

571 if (argc < 2) {

572 printf("usage: %s output_file\n"

573 "API example program to output a media file with libavformat.\n"

574 "This program generates a synthetic audio and video stream, encodes and\n"

575 "muxes them into a file named output_file.\n"

576 "The output format is automatically guessed according to the file extension.\n"

577 "Raw images can also be output by using '%%d' in the filename.\n"

578 "\n", argv[0]);

579 return 1;

580 }

581

582 filename = argv[1];

583 if (argc > 3 && !strcmp(argv[2], "-flags")) {

584 av_dict_set(&opt, argv[2]+1, argv[3], 0);

585 }

586

587 /* allocate the output media context */

588 avformat_alloc_output_context2(&oc, NULL, NULL, filename);

589 if (!oc) {

590 printf("Could not deduce output format from file extension: using MPEG.\n");

591 avformat_alloc_output_context2(&oc, NULL, "mpeg", filename);

592 }

593 if (!oc)

594 return 1;

595

596 fmt = oc->oformat;

597

598 /* Add the audio and video streams using the default format codecs

599 * and initialize the codecs. */

600 if (fmt->video_codec != AV_CODEC_ID_NONE) {

601 add_stream(&video_st, oc, &video_codec, fmt->video_codec);

602 have_video = 1;

603 encode_video = 1;

604 }

605 if (fmt->audio_codec != AV_CODEC_ID_NONE) {

606 add_stream(&audio_st, oc, &audio_codec, fmt->audio_codec);

607 have_audio = 1;

608 encode_audio = 1;

609 }

610

611 /* Now that all the parameters are set, we can open the audio and

612 * video codecs and allocate the necessary encode buffers. */

613 if (have_video)

614 open_video(oc, video_codec, &video_st, opt);

615

616 if (have_audio)

617 open_audio(oc, audio_codec, &audio_st, opt);

618

619 av_dump_format(oc, 0, filename, 1);

620

621 /* open the output file, if needed */

622 if (!(fmt->flags & AVFMT_NOFILE)) {

623 ret = avio_open(&oc->pb, filename, AVIO_FLAG_WRITE);

624 if (ret < 0) {

625 fprintf(stderr, "Could not open '%s': %s\n", filename,

626 av_err2str(ret));

627 return 1;

628 }

629 }

630

631 /* Write the stream header, if any. */

632 ret = avformat_write_header(oc, &opt);

633 if (ret < 0) {

634 fprintf(stderr, "Error occurred when opening output file: %s\n",

635 av_err2str(ret));

636 return 1;

637 }

638

639 while (encode_video || encode_audio) {

640 /* select the stream to encode */

641 if (encode_video &&

642 (!encode_audio || av_compare_ts(video_st.next_pts, video_st.st->codec->time_base,

643 audio_st.next_pts, audio_st.st->codec->time_base) <= 0)) {

644 encode_video = !write_video_frame(oc, &video_st);

645 } else {

646 encode_audio = !write_audio_frame(oc, &audio_st);

647 }

648 }

649

650 /* Write the trailer, if any. The trailer must be written before you

651 * close the CodecContexts open when you wrote the header; otherwise

652 * av_write_trailer() may try to use memory that was freed on

653 * av_codec_close(). */

654 av_write_trailer(oc);

655

656 /* Close each codec. */

657 if (have_video)

658 close_stream(oc, &video_st);

659 if (have_audio)

660 close_stream(oc, &audio_st);

661

662 if (!(fmt->flags & AVFMT_NOFILE))

663 /* Close the output file. */

664 avio_closep(&oc->pb);

665

666 /* free the stream */

667 avformat_free_context(oc);

668

669 return 0;

670 }

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