2 * Libavformat API example: Output a media file in any supported
3 * libavformat format. The default codecs are used.
5 * Copyright (c) 2003 Fabrice Bellard
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8 * of this software and associated documentation files (the "Software"), to deal
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30 #define M_PI 3.1415926535897931
35 /* 5 seconds stream duration */
36 #define STREAM_DURATION 5.0
37 #define STREAM_FRAME_RATE 25 /* 25 images/s */
38 #define STREAM_NB_FRAMES ((int)(STREAM_DURATION * STREAM_FRAME_RATE))
40 /**************************************************************/
43 float t, tincr, tincr2;
45 uint8_t *audio_outbuf;
46 int audio_outbuf_size;
47 int audio_input_frame_size;
50 * add an audio output stream
52 AVStream *add_audio_stream(AVFormatContext *oc, int codec_id)
57 st = av_new_stream(oc, 1);
59 fprintf(stderr, "Could not alloc stream\n");
64 c->codec_id = codec_id;
65 c->codec_type = CODEC_TYPE_AUDIO;
67 /* put sample parameters */
69 c->sample_rate = 44100;
74 void open_audio(AVFormatContext *oc, AVStream *st)
81 /* find the audio encoder */
82 codec = avcodec_find_encoder(c->codec_id);
84 fprintf(stderr, "codec not found\n");
89 if (avcodec_open(c, codec) < 0) {
90 fprintf(stderr, "could not open codec\n");
94 /* init signal generator */
96 tincr = 2 * M_PI * 110.0 / c->sample_rate;
97 /* increment frequency by 110 Hz per second */
98 tincr2 = 2 * M_PI * 110.0 / c->sample_rate / c->sample_rate;
100 audio_outbuf_size = 10000;
101 audio_outbuf = malloc(audio_outbuf_size);
103 /* ugly hack for PCM codecs (will be removed ASAP with new PCM
104 support to compute the input frame size in samples */
105 if (c->frame_size <= 1) {
106 audio_input_frame_size = audio_outbuf_size / c->channels;
107 switch(st->codec.codec_id) {
108 case CODEC_ID_PCM_S16LE:
109 case CODEC_ID_PCM_S16BE:
110 case CODEC_ID_PCM_U16LE:
111 case CODEC_ID_PCM_U16BE:
112 audio_input_frame_size >>= 1;
118 audio_input_frame_size = c->frame_size;
120 samples = malloc(audio_input_frame_size * 2 * c->channels);
123 /* prepare a 16 bit dummy audio frame of 'frame_size' samples and
124 'nb_channels' channels */
125 void get_audio_frame(int16_t *samples, int frame_size, int nb_channels)
131 for(j=0;j<frame_size;j++) {
132 v = (int)(sin(t) * 10000);
133 for(i = 0; i < nb_channels; i++)
140 void write_audio_frame(AVFormatContext *oc, AVStream *st)
148 get_audio_frame(samples, audio_input_frame_size, c->channels);
150 out_size = avcodec_encode_audio(c, audio_outbuf, audio_outbuf_size, samples);
152 /* write the compressed frame in the media file */
153 if (av_write_frame(oc, st->index, audio_outbuf, out_size) != 0) {
154 fprintf(stderr, "Error while writing audio frame\n");
159 void close_audio(AVFormatContext *oc, AVStream *st)
161 avcodec_close(&st->codec);
164 av_free(audio_outbuf);
167 /**************************************************************/
170 AVFrame *picture, *tmp_picture;
171 uint8_t *video_outbuf;
172 int frame_count, video_outbuf_size;
174 /* add a video output stream */
175 AVStream *add_video_stream(AVFormatContext *oc, int codec_id)
180 st = av_new_stream(oc, 0);
182 fprintf(stderr, "Could not alloc stream\n");
187 c->codec_id = codec_id;
188 c->codec_type = CODEC_TYPE_VIDEO;
190 /* put sample parameters */
191 c->bit_rate = 400000;
192 /* resolution must be a multiple of two */
195 /* frames per second */
196 c->frame_rate = STREAM_FRAME_RATE;
197 c->frame_rate_base = 1;
198 c->gop_size = 12; /* emit one intra frame every twelve frames at most */
199 if (c->codec_id == CODEC_ID_MPEG1VIDEO ||
200 c->codec_id == CODEC_ID_MPEG2VIDEO) {
201 /* just for testing, we also add B frames */
207 AVFrame *alloc_picture(int pix_fmt, int width, int height)
210 uint8_t *picture_buf;
213 picture = avcodec_alloc_frame();
216 size = avpicture_get_size(pix_fmt, width, height);
217 picture_buf = malloc(size);
222 avpicture_fill((AVPicture *)picture, picture_buf,
223 pix_fmt, width, height);
227 void open_video(AVFormatContext *oc, AVStream *st)
234 /* find the video encoder */
235 codec = avcodec_find_encoder(c->codec_id);
237 fprintf(stderr, "codec not found\n");
242 if (avcodec_open(c, codec) < 0) {
243 fprintf(stderr, "could not open codec\n");
248 if (!(oc->oformat->flags & AVFMT_RAWPICTURE)) {
249 /* allocate output buffer */
250 /* XXX: API change will be done */
251 video_outbuf_size = 200000;
252 video_outbuf = malloc(video_outbuf_size);
255 /* allocate the encoded raw picture */
256 picture = alloc_picture(c->pix_fmt, c->width, c->height);
258 fprintf(stderr, "Could not allocate picture\n");
262 /* if the output format is not YUV420P, then a temporary YUV420P
263 picture is needed too. It is then converted to the required
266 if (c->pix_fmt != PIX_FMT_YUV420P) {
267 tmp_picture = alloc_picture(PIX_FMT_YUV420P, c->width, c->height);
269 fprintf(stderr, "Could not allocate temporary picture\n");
275 /* prepare a dummy image */
276 void fill_yuv_image(AVFrame *pict, int frame_index, int width, int height)
283 for(y=0;y<height;y++) {
284 for(x=0;x<width;x++) {
285 pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
290 for(y=0;y<height/2;y++) {
291 for(x=0;x<width/2;x++) {
292 pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
293 pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
298 void write_video_frame(AVFormatContext *oc, AVStream *st)
302 AVFrame *picture_ptr;
306 if (frame_count >= STREAM_NB_FRAMES) {
307 /* no more frame to compress. The codec has a latency of a few
308 frames if using B frames, so we get the last frames by
309 passing a NULL picture */
312 if (c->pix_fmt != PIX_FMT_YUV420P) {
313 /* as we only generate a YUV420P picture, we must convert it
314 to the codec pixel format if needed */
315 fill_yuv_image(tmp_picture, frame_count, c->width, c->height);
316 img_convert((AVPicture *)picture, c->pix_fmt,
317 (AVPicture *)tmp_picture, PIX_FMT_YUV420P,
318 c->width, c->height);
320 fill_yuv_image(picture, frame_count, c->width, c->height);
322 picture_ptr = picture;
326 if (oc->oformat->flags & AVFMT_RAWPICTURE) {
327 /* raw video case. The API will change slightly in the near
329 ret = av_write_frame(oc, st->index,
330 (uint8_t *)picture_ptr, sizeof(AVPicture));
332 /* encode the image */
333 out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture_ptr);
334 /* if zero size, it means the image was buffered */
336 /* write the compressed frame in the media file */
337 /* XXX: in case of B frames, the pts is not yet valid */
338 ret = av_write_frame(oc, st->index, video_outbuf, out_size);
344 fprintf(stderr, "Error while writing video frame\n");
350 void close_video(AVFormatContext *oc, AVStream *st)
352 avcodec_close(&st->codec);
353 av_free(picture->data[0]);
356 av_free(tmp_picture->data[0]);
357 av_free(tmp_picture);
359 av_free(video_outbuf);
362 /**************************************************************/
363 /* media file output */
365 int main(int argc, char **argv)
367 const char *filename;
370 AVStream *audio_st, *video_st;
371 double audio_pts, video_pts;
374 /* initialize libavcodec, and register all codecs and formats */
378 printf("usage: %s output_file\n"
379 "API example program to output a media file with libavformat.\n"
380 "The output format is automatically guessed according to the file extension.\n"
381 "Raw images can also be output by using '%%d' in the filename\n"
388 /* auto detect the output format from the name. default is
390 fmt = guess_format(NULL, filename, NULL);
392 printf("Could not deduce output format from file extension: using MPEG.\n");
393 fmt = guess_format("mpeg", NULL, NULL);
396 fprintf(stderr, "Could not find suitable output format\n");
400 /* allocate the output media context */
401 oc = av_mallocz(sizeof(AVFormatContext));
403 fprintf(stderr, "Memory error\n");
407 snprintf(oc->filename, sizeof(oc->filename), "%s", filename);
409 /* add the audio and video streams using the default format codecs
410 and initialize the codecs */
413 if (fmt->video_codec != CODEC_ID_NONE) {
414 video_st = add_video_stream(oc, fmt->video_codec);
416 if (fmt->audio_codec != CODEC_ID_NONE) {
417 audio_st = add_audio_stream(oc, fmt->audio_codec);
420 /* set the output parameters (must be done even if no
422 if (av_set_parameters(oc, NULL) < 0) {
423 fprintf(stderr, "Invalid output format parameters\n");
427 dump_format(oc, 0, filename, 1);
429 /* now that all the parameters are set, we can open the audio and
430 video codecs and allocate the necessary encode buffers */
432 open_video(oc, video_st);
434 open_audio(oc, audio_st);
436 /* open the output file, if needed */
437 if (!(fmt->flags & AVFMT_NOFILE)) {
438 if (url_fopen(&oc->pb, filename, URL_WRONLY) < 0) {
439 fprintf(stderr, "Could not open '%s'\n", filename);
444 /* write the stream header, if any */
448 /* compute current audio and video time */
450 audio_pts = (double)audio_st->pts.val * oc->pts_num / oc->pts_den;
455 video_pts = (double)video_st->pts.val * oc->pts_num / oc->pts_den;
459 if ((!audio_st || audio_pts >= STREAM_DURATION) &&
460 (!video_st || video_pts >= STREAM_DURATION))
463 /* write interleaved audio and video frames */
464 if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
465 write_audio_frame(oc, audio_st);
467 write_video_frame(oc, video_st);
471 /* close each codec */
473 close_video(oc, video_st);
475 close_audio(oc, audio_st);
477 /* write the trailer, if any */
478 av_write_trailer(oc);
480 /* free the streams */
481 for(i = 0; i < oc->nb_streams; i++) {
482 av_freep(&oc->streams[i]);
485 if (!(fmt->flags & AVFMT_NOFILE)) {
486 /* close the output file */
490 /* free the stream */