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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31 /* 5 seconds stream duration */
32 #define STREAM_DURATION 5.0
35 /**************************************************************/
38 float t, tincr, tincr2;
40 uint8_t *audio_outbuf;
41 int audio_outbuf_size;
42 int audio_input_frame_size;
45 * add an audio output stream
47 AVStream *add_audio_stream(AVFormatContext *oc, int codec_id)
52 st = av_new_stream(oc, 1);
54 fprintf(stderr, "Could not alloc stream\n");
59 c->codec_id = codec_id;
60 c->codec_type = CODEC_TYPE_AUDIO;
62 /* put sample parameters */
64 c->sample_rate = 44100;
69 void open_audio(AVFormatContext *oc, AVStream *st)
76 /* find the audio encoder */
77 codec = avcodec_find_encoder(c->codec_id);
79 fprintf(stderr, "codec not found\n");
84 if (avcodec_open(c, codec) < 0) {
85 fprintf(stderr, "could not open codec\n");
89 /* init signal generator */
91 tincr = 2 * M_PI * 110.0 / c->sample_rate;
92 /* increment frequency by 110 Hz per second */
93 tincr2 = 2 * M_PI * 110.0 / c->sample_rate / c->sample_rate;
95 audio_outbuf_size = 10000;
96 audio_outbuf = malloc(audio_outbuf_size);
98 /* ugly hack for PCM codecs (will be removed ASAP with new PCM
99 support to compute the input frame size in samples */
100 if (c->frame_size <= 1) {
101 audio_input_frame_size = audio_outbuf_size / c->channels;
102 switch(st->codec.codec_id) {
103 case CODEC_ID_PCM_S16LE:
104 case CODEC_ID_PCM_S16BE:
105 case CODEC_ID_PCM_U16LE:
106 case CODEC_ID_PCM_U16BE:
107 audio_input_frame_size >>= 1;
113 audio_input_frame_size = c->frame_size;
115 samples = malloc(audio_input_frame_size * 2 * c->channels);
118 /* prepare a 16 bit dummy audio frame of 'frame_size' samples and
119 'nb_channels' channels */
120 void get_audio_frame(int16_t *samples, int frame_size, int nb_channels)
126 for(j=0;j<frame_size;j++) {
127 v = (int)(sin(t) * 10000);
128 for(i = 0; i < nb_channels; i++)
135 void write_audio_frame(AVFormatContext *oc, AVStream *st)
143 get_audio_frame(samples, audio_input_frame_size, c->channels);
145 out_size = avcodec_encode_audio(c, audio_outbuf, audio_outbuf_size, samples);
147 /* write the compressed frame in the media file */
148 if (av_write_frame(oc, st->index, audio_outbuf, out_size) != 0) {
149 fprintf(stderr, "Error while writing audio frame\n");
154 void close_audio(AVFormatContext *oc, AVStream *st)
156 avcodec_close(&st->codec);
159 av_free(audio_outbuf);
162 /**************************************************************/
165 AVFrame *picture, *tmp_picture;
166 uint8_t *video_outbuf;
167 int frame_count, video_outbuf_size;
169 /* add a video output stream */
170 AVStream *add_video_stream(AVFormatContext *oc, int codec_id)
175 st = av_new_stream(oc, 0);
177 fprintf(stderr, "Could not alloc stream\n");
182 c->codec_id = codec_id;
183 c->codec_type = CODEC_TYPE_VIDEO;
185 /* put sample parameters */
186 c->bit_rate = 400000;
187 /* resolution must be a multiple of two */
190 /* frames per second */
192 c->frame_rate_base= 1;
193 c->gop_size = 12; /* emit one intra frame every twelve frames */
198 AVFrame *alloc_picture(int pix_fmt, int width, int height)
201 uint8_t *picture_buf;
204 picture = avcodec_alloc_frame();
207 size = avpicture_get_size(pix_fmt, width, height);
208 picture_buf = malloc(size);
213 avpicture_fill((AVPicture *)picture, picture_buf,
214 pix_fmt, width, height);
218 void open_video(AVFormatContext *oc, AVStream *st)
225 /* find the video encoder */
226 codec = avcodec_find_encoder(c->codec_id);
228 fprintf(stderr, "codec not found\n");
233 if (avcodec_open(c, codec) < 0) {
234 fprintf(stderr, "could not open codec\n");
239 if (!(oc->oformat->flags & AVFMT_RAWPICTURE)) {
240 /* allocate output buffer */
241 /* XXX: API change will be done */
242 video_outbuf_size = 200000;
243 video_outbuf = malloc(video_outbuf_size);
246 /* allocate the encoded raw picture */
247 picture = alloc_picture(c->pix_fmt, c->width, c->height);
249 fprintf(stderr, "Could not allocate picture\n");
253 /* if the output format is not YUV420P, then a temporary YUV420P
254 picture is needed too. It is then converted to the required
257 if (c->pix_fmt != PIX_FMT_YUV420P) {
258 tmp_picture = alloc_picture(PIX_FMT_YUV420P, c->width, c->height);
260 fprintf(stderr, "Could not allocate temporary picture\n");
266 /* prepare a dummy image */
267 void fill_yuv_image(AVFrame *pict, int frame_index, int width, int height)
274 for(y=0;y<height;y++) {
275 for(x=0;x<width;x++) {
276 pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
281 for(y=0;y<height/2;y++) {
282 for(x=0;x<width/2;x++) {
283 pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
284 pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
289 void write_video_frame(AVFormatContext *oc, AVStream *st)
296 if (c->pix_fmt != PIX_FMT_YUV420P) {
297 /* as we only generate a YUV420P picture, we must convert it
298 to the codec pixel format if needed */
299 fill_yuv_image(tmp_picture, frame_count, c->width, c->height);
300 img_convert((AVPicture *)picture, c->pix_fmt,
301 (AVPicture *)tmp_picture, PIX_FMT_YUV420P,
302 c->width, c->height);
304 fill_yuv_image(picture, frame_count, c->width, c->height);
308 if (oc->oformat->flags & AVFMT_RAWPICTURE) {
309 /* raw video case. The API will change slightly in the near
311 ret = av_write_frame(oc, st->index,
312 (uint8_t *)picture, sizeof(AVPicture));
314 /* encode the image */
315 out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture);
317 /* write the compressed frame in the media file */
318 ret = av_write_frame(oc, st->index, video_outbuf, out_size);
321 fprintf(stderr, "Error while writing video frame\n");
327 void close_video(AVFormatContext *oc, AVStream *st)
329 avcodec_close(&st->codec);
330 av_free(picture->data[0]);
333 av_free(tmp_picture->data[0]);
334 av_free(tmp_picture);
336 av_free(video_outbuf);
339 /**************************************************************/
340 /* media file output */
342 int main(int argc, char **argv)
344 const char *filename;
347 AVStream *audio_st, *video_st;
348 double audio_pts, video_pts;
351 /* initialize libavcodec, and register all codecs and formats */
355 printf("usage: %s output_file\n"
356 "API example program to output a media file with libavformat.\n"
357 "The output format is automatically guessed according to the file extension.\n"
358 "Raw images can also be output by using '%%d' in the filename\n"
365 /* auto detect the output format from the name. default is
367 fmt = guess_format(NULL, filename, NULL);
369 printf("Could not deduce output format from file extension: using MPEG.\n");
370 fmt = guess_format("mpeg", NULL, NULL);
373 fprintf(stderr, "Could not find suitable output format\n");
377 /* allocate the output media context */
378 oc = av_mallocz(sizeof(AVFormatContext));
380 fprintf(stderr, "Memory error\n");
384 snprintf(oc->filename, sizeof(oc->filename), "%s", filename);
386 /* add the audio and video streams using the default format codecs
387 and initialize the codecs */
390 if (fmt->video_codec != CODEC_ID_NONE) {
391 video_st = add_video_stream(oc, fmt->video_codec);
393 if (fmt->audio_codec != CODEC_ID_NONE) {
394 audio_st = add_audio_stream(oc, fmt->audio_codec);
397 /* set the output parameters (must be done even if no
399 if (av_set_parameters(oc, NULL) < 0) {
400 fprintf(stderr, "Invalid output format parameters\n");
404 dump_format(oc, 0, filename, 1);
406 /* now that all the parameters are set, we can open the audio and
407 video codecs and allocate the necessary encode buffers */
409 open_video(oc, video_st);
411 open_audio(oc, audio_st);
413 /* open the output file, if needed */
414 if (!(fmt->flags & AVFMT_NOFILE)) {
415 if (url_fopen(&oc->pb, filename, URL_WRONLY) < 0) {
416 fprintf(stderr, "Could not open '%s'\n", filename);
421 /* write the stream header, if any */
425 /* compute current audio and video time */
427 audio_pts = (double)audio_st->pts.val * oc->pts_num / oc->pts_den;
432 video_pts = (double)video_st->pts.val * oc->pts_num / oc->pts_den;
436 if ((!audio_st || audio_pts >= STREAM_DURATION) &&
437 (!video_st || video_pts >= STREAM_DURATION))
440 /* write interleaved audio and video frames */
441 if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
442 write_audio_frame(oc, audio_st);
444 write_video_frame(oc, video_st);
448 /* close each codec */
450 close_video(oc, video_st);
452 close_audio(oc, audio_st);
454 /* write the trailer, if any */
455 av_write_trailer(oc);
457 /* free the streams */
458 for(i = 0; i < oc->nb_streams; i++) {
459 av_freep(&oc->streams[i]);
462 if (!(fmt->flags & AVFMT_NOFILE)) {
463 /* close the output file */
467 /* free the stream */