2 * Copyright (c) 2003 Fabrice Bellard
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:
11 * The above copyright notice and this permission notice shall be included in
12 * all copies or substantial portions of the Software.
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
25 * libavformat API example.
27 * Output a media file in any supported libavformat format. The default
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 {
56 /* pts of the next frame that will be generated */
63 float t, tincr, tincr2;
65 struct SwsContext *sws_ctx;
66 struct SwrContext *swr_ctx;
69 static void log_packet(const AVFormatContext *fmt_ctx, const AVPacket *pkt)
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),
80 static int write_frame(AVFormatContext *fmt_ctx, const AVRational *time_base, AVStream *st, AVPacket *pkt)
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);
91 /* Add an output stream. */
92 static void add_stream(OutputStream *ost, AVFormatContext *oc,
94 enum AVCodecID codec_id)
99 /* find the encoder */
100 *codec = avcodec_find_encoder(codec_id);
102 fprintf(stderr, "Could not find encoder for '%s'\n",
103 avcodec_get_name(codec_id));
107 ost->st = avformat_new_stream(oc, *codec);
109 fprintf(stderr, "Could not allocate stream\n");
112 ost->st->id = oc->nb_streams-1;
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;
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;
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;
137 c->channels = av_get_channel_layout_nb_channels(c->channel_layout);
138 ost->st->time_base = (AVRational){ 1, c->sample_rate };
141 case AVMEDIA_TYPE_VIDEO:
142 c->codec_id = codec_id;
144 c->bit_rate = 400000;
145 /* Resolution must be a multiple of two. */
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
152 ost->st->time_base = (AVRational){ 1, STREAM_FRAME_RATE };
153 c->time_base = ost->st->time_base;
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 */
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. */
173 /* Some formats want stream headers to be separate. */
174 if (oc->oformat->flags & AVFMT_GLOBALHEADER)
175 c->flags |= CODEC_FLAG_GLOBAL_HEADER;
178 /**************************************************************/
181 static AVFrame *alloc_audio_frame(enum AVSampleFormat sample_fmt,
182 uint64_t channel_layout,
183 int sample_rate, int nb_samples)
185 AVFrame *frame = av_frame_alloc();
189 fprintf(stderr, "Error allocating an audio frame\n");
193 frame->format = sample_fmt;
194 frame->channel_layout = channel_layout;
195 frame->sample_rate = sample_rate;
196 frame->nb_samples = nb_samples;
199 ret = av_frame_get_buffer(frame, 0);
201 fprintf(stderr, "Error allocating an audio buffer\n");
209 static void open_audio(AVFormatContext *oc, AVCodec *codec, OutputStream *ost, AVDictionary *opt_arg)
214 AVDictionary *opt = NULL;
219 av_dict_copy(&opt, opt_arg, 0);
220 ret = avcodec_open2(c, codec, &opt);
223 fprintf(stderr, "Could not open audio codec: %s\n", av_err2str(ret));
227 /* init signal generator */
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;
233 if (c->codec->capabilities & CODEC_CAP_VARIABLE_FRAME_SIZE)
236 nb_samples = c->frame_size;
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);
243 /* create resampler context */
244 ost->swr_ctx = swr_alloc();
246 fprintf(stderr, "Could not allocate resampler context\n");
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);
258 /* initialize the resampling context */
259 if ((ret = swr_init(ost->swr_ctx)) < 0) {
260 fprintf(stderr, "Failed to initialize the resampling context\n");
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)
269 AVFrame *frame = ost->tmp_frame;
271 int16_t *q = (int16_t*)frame->data[0];
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)
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++)
282 ost->t += ost->tincr;
283 ost->tincr += ost->tincr2;
286 frame->pts = ost->next_pts;
287 ost->next_pts += frame->nb_samples;
293 * encode one audio frame and send it to the muxer
294 * return 1 when encoding is finished, 0 otherwise
296 static int write_audio_frame(AVFormatContext *oc, OutputStream *ost)
299 AVPacket pkt = { 0 }; // data and size must be 0;
305 av_init_packet(&pkt);
308 frame = get_audio_frame(ost);
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);
317 /* when we pass a frame to the encoder, it may keep a reference to it
319 * make sure we do not overwrite it here
321 ret = av_frame_make_writable(ost->frame);
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);
330 fprintf(stderr, "Error while converting\n");
335 frame->pts = av_rescale_q(ost->samples_count, (AVRational){1, c->sample_rate}, c->time_base);
336 ost->samples_count += dst_nb_samples;
339 ret = avcodec_encode_audio2(c, &pkt, frame, &got_packet);
341 fprintf(stderr, "Error encoding audio frame: %s\n", av_err2str(ret));
346 ret = write_frame(oc, &c->time_base, ost->st, &pkt);
348 fprintf(stderr, "Error while writing audio frame: %s\n",
354 return (frame || got_packet) ? 0 : 1;
357 /**************************************************************/
360 static AVFrame *alloc_picture(enum AVPixelFormat pix_fmt, int width, int height)
365 picture = av_frame_alloc();
369 picture->format = pix_fmt;
370 picture->width = width;
371 picture->height = height;
373 /* allocate the buffers for the frame data */
374 ret = av_frame_get_buffer(picture, 32);
376 fprintf(stderr, "Could not allocate frame data.\n");
383 static void open_video(AVFormatContext *oc, AVCodec *codec, OutputStream *ost, AVDictionary *opt_arg)
386 AVCodecContext *c = ost->st->codec;
387 AVDictionary *opt = NULL;
389 av_dict_copy(&opt, opt_arg, 0);
392 ret = avcodec_open2(c, codec, &opt);
395 fprintf(stderr, "Could not open video codec: %s\n", av_err2str(ret));
399 /* allocate and init a re-usable frame */
400 ost->frame = alloc_picture(c->pix_fmt, c->width, c->height);
402 fprintf(stderr, "Could not allocate video frame\n");
406 /* If the output format is not YUV420P, then a temporary YUV420P
407 * picture is needed too. It is then converted to the required
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");
419 /* Prepare a dummy image. */
420 static void fill_yuv_image(AVFrame *pict, int frame_index,
421 int width, int height)
425 /* when we pass a frame to the encoder, it may keep a reference to it
427 * make sure we do not overwrite it here
429 ret = av_frame_make_writable(pict);
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;
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;
449 static AVFrame *get_video_frame(OutputStream *ost)
451 AVCodecContext *c = ost->st->codec;
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)
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 */
462 ost->sws_ctx = sws_getContext(c->width, c->height,
466 SCALE_FLAGS, NULL, NULL, NULL);
469 "Could not initialize the conversion context\n");
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);
478 fill_yuv_image(ost->frame, ost->next_pts, c->width, c->height);
481 ost->frame->pts = ost->next_pts++;
487 * encode one video frame and send it to the muxer
488 * return 1 when encoding is finished, 0 otherwise
490 static int write_video_frame(AVFormatContext *oc, OutputStream *ost)
499 frame = get_video_frame(ost);
501 if (oc->oformat->flags & AVFMT_RAWPICTURE) {
502 /* a hack to avoid data copy with some raw video muxers */
504 av_init_packet(&pkt);
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);
514 pkt.pts = pkt.dts = frame->pts;
515 av_packet_rescale_ts(&pkt, c->time_base, ost->st->time_base);
517 ret = av_interleaved_write_frame(oc, &pkt);
519 AVPacket pkt = { 0 };
520 av_init_packet(&pkt);
522 /* encode the image */
523 ret = avcodec_encode_video2(c, &pkt, frame, &got_packet);
525 fprintf(stderr, "Error encoding video frame: %s\n", av_err2str(ret));
530 ret = write_frame(oc, &c->time_base, ost->st, &pkt);
537 fprintf(stderr, "Error while writing video frame: %s\n", av_err2str(ret));
541 return (frame || got_packet) ? 0 : 1;
544 static void close_stream(AVFormatContext *oc, OutputStream *ost)
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);
553 /**************************************************************/
554 /* media file output */
556 int main(int argc, char **argv)
558 OutputStream video_st = { 0 }, audio_st = { 0 };
559 const char *filename;
562 AVCodec *audio_codec, *video_codec;
564 int have_video = 0, have_audio = 0;
565 int encode_video = 0, encode_audio = 0;
566 AVDictionary *opt = NULL;
568 /* Initialize libavcodec, and register all codecs and formats. */
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"
583 if (argc > 3 && !strcmp(argv[2], "-flags")) {
584 av_dict_set(&opt, argv[2]+1, argv[3], 0);
587 /* allocate the output media context */
588 avformat_alloc_output_context2(&oc, NULL, NULL, filename);
590 printf("Could not deduce output format from file extension: using MPEG.\n");
591 avformat_alloc_output_context2(&oc, NULL, "mpeg", filename);
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);
605 if (fmt->audio_codec != AV_CODEC_ID_NONE) {
606 add_stream(&audio_st, oc, &audio_codec, fmt->audio_codec);
611 /* Now that all the parameters are set, we can open the audio and
612 * video codecs and allocate the necessary encode buffers. */
614 open_video(oc, video_codec, &video_st, opt);
617 open_audio(oc, audio_codec, &audio_st, opt);
619 av_dump_format(oc, 0, filename, 1);
621 /* open the output file, if needed */
622 if (!(fmt->flags & AVFMT_NOFILE)) {
623 ret = avio_open(&oc->pb, filename, AVIO_FLAG_WRITE);
625 fprintf(stderr, "Could not open '%s': %s\n", filename,
631 /* Write the stream header, if any. */
632 ret = avformat_write_header(oc, &opt);
634 fprintf(stderr, "Error occurred when opening output file: %s\n",
639 while (encode_video || encode_audio) {
640 /* select the stream to encode */
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);
646 encode_audio = !write_audio_frame(oc, &audio_st);
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);
656 /* Close each codec. */
658 close_stream(oc, &video_st);
660 close_stream(oc, &audio_st);
662 if (!(fmt->flags & AVFMT_NOFILE))
663 /* Close the output file. */
664 avio_closep(&oc->pb);
666 /* free the stream */
667 avformat_free_context(oc);