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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31 #define M_PI 3.1415926535897931
36 /* 5 seconds stream duration */
37 #define STREAM_DURATION 5.0
38 #define STREAM_FRAME_RATE 25 /* 25 images/s */
39 #define STREAM_NB_FRAMES ((int)(STREAM_DURATION * STREAM_FRAME_RATE))
41 /**************************************************************/
44 float t, tincr, tincr2;
46 uint8_t *audio_outbuf;
47 int audio_outbuf_size;
48 int audio_input_frame_size;
51 * add an audio output stream
53 AVStream *add_audio_stream(AVFormatContext *oc, int codec_id)
58 st = av_new_stream(oc, 1);
60 fprintf(stderr, "Could not alloc stream\n");
65 c->codec_id = codec_id;
66 c->codec_type = CODEC_TYPE_AUDIO;
68 /* put sample parameters */
70 c->sample_rate = 44100;
75 void open_audio(AVFormatContext *oc, AVStream *st)
82 /* find the audio encoder */
83 codec = avcodec_find_encoder(c->codec_id);
85 fprintf(stderr, "codec not found\n");
90 if (avcodec_open(c, codec) < 0) {
91 fprintf(stderr, "could not open codec\n");
95 /* init signal generator */
97 tincr = 2 * M_PI * 110.0 / c->sample_rate;
98 /* increment frequency by 110 Hz per second */
99 tincr2 = 2 * M_PI * 110.0 / c->sample_rate / c->sample_rate;
101 audio_outbuf_size = 10000;
102 audio_outbuf = malloc(audio_outbuf_size);
104 /* ugly hack for PCM codecs (will be removed ASAP with new PCM
105 support to compute the input frame size in samples */
106 if (c->frame_size <= 1) {
107 audio_input_frame_size = audio_outbuf_size / c->channels;
108 switch(st->codec.codec_id) {
109 case CODEC_ID_PCM_S16LE:
110 case CODEC_ID_PCM_S16BE:
111 case CODEC_ID_PCM_U16LE:
112 case CODEC_ID_PCM_U16BE:
113 audio_input_frame_size >>= 1;
119 audio_input_frame_size = c->frame_size;
121 samples = malloc(audio_input_frame_size * 2 * c->channels);
124 /* prepare a 16 bit dummy audio frame of 'frame_size' samples and
125 'nb_channels' channels */
126 void get_audio_frame(int16_t *samples, int frame_size, int nb_channels)
132 for(j=0;j<frame_size;j++) {
133 v = (int)(sin(t) * 10000);
134 for(i = 0; i < nb_channels; i++)
141 void write_audio_frame(AVFormatContext *oc, AVStream *st)
145 av_init_packet(&pkt);
149 get_audio_frame(samples, audio_input_frame_size, c->channels);
151 pkt.size= avcodec_encode_audio(c, audio_outbuf, audio_outbuf_size, samples);
153 pkt.pts= c->coded_frame->pts;
154 pkt.flags |= PKT_FLAG_KEY;
155 pkt.stream_index= st->index;
156 pkt.data= audio_outbuf;
158 /* write the compressed frame in the media file */
159 if (av_write_frame(oc, &pkt) != 0) {
160 fprintf(stderr, "Error while writing audio frame\n");
165 void close_audio(AVFormatContext *oc, AVStream *st)
167 avcodec_close(&st->codec);
170 av_free(audio_outbuf);
173 /**************************************************************/
176 AVFrame *picture, *tmp_picture;
177 uint8_t *video_outbuf;
178 int frame_count, video_outbuf_size;
180 /* add a video output stream */
181 AVStream *add_video_stream(AVFormatContext *oc, int codec_id)
186 st = av_new_stream(oc, 0);
188 fprintf(stderr, "Could not alloc stream\n");
193 c->codec_id = codec_id;
194 c->codec_type = CODEC_TYPE_VIDEO;
196 /* put sample parameters */
197 c->bit_rate = 400000;
198 /* resolution must be a multiple of two */
201 /* frames per second */
202 c->time_base.den = STREAM_FRAME_RATE;
203 c->time_base.num = 1;
204 c->gop_size = 12; /* emit one intra frame every twelve frames at most */
205 if (c->codec_id == CODEC_ID_MPEG2VIDEO) {
206 /* just for testing, we also add B frames */
209 if (c->codec_id == CODEC_ID_MPEG1VIDEO){
210 /* needed to avoid using macroblocks in which some coeffs overflow
211 this doesnt happen with normal video, it just happens here as the
212 motion of the chroma plane doesnt match the luma plane */
215 // some formats want stream headers to be seperate
216 if(!strcmp(oc->oformat->name, "mp4") || !strcmp(oc->oformat->name, "mov") || !strcmp(oc->oformat->name, "3gp"))
217 c->flags |= CODEC_FLAG_GLOBAL_HEADER;
222 AVFrame *alloc_picture(int pix_fmt, int width, int height)
225 uint8_t *picture_buf;
228 picture = avcodec_alloc_frame();
231 size = avpicture_get_size(pix_fmt, width, height);
232 picture_buf = malloc(size);
237 avpicture_fill((AVPicture *)picture, picture_buf,
238 pix_fmt, width, height);
242 void open_video(AVFormatContext *oc, AVStream *st)
249 /* find the video encoder */
250 codec = avcodec_find_encoder(c->codec_id);
252 fprintf(stderr, "codec not found\n");
257 if (avcodec_open(c, codec) < 0) {
258 fprintf(stderr, "could not open codec\n");
263 if (!(oc->oformat->flags & AVFMT_RAWPICTURE)) {
264 /* allocate output buffer */
265 /* XXX: API change will be done */
266 video_outbuf_size = 200000;
267 video_outbuf = malloc(video_outbuf_size);
270 /* allocate the encoded raw picture */
271 picture = alloc_picture(c->pix_fmt, c->width, c->height);
273 fprintf(stderr, "Could not allocate picture\n");
277 /* if the output format is not YUV420P, then a temporary YUV420P
278 picture is needed too. It is then converted to the required
281 if (c->pix_fmt != PIX_FMT_YUV420P) {
282 tmp_picture = alloc_picture(PIX_FMT_YUV420P, c->width, c->height);
284 fprintf(stderr, "Could not allocate temporary picture\n");
290 /* prepare a dummy image */
291 void fill_yuv_image(AVFrame *pict, int frame_index, int width, int height)
298 for(y=0;y<height;y++) {
299 for(x=0;x<width;x++) {
300 pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
305 for(y=0;y<height/2;y++) {
306 for(x=0;x<width/2;x++) {
307 pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
308 pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
313 void write_video_frame(AVFormatContext *oc, AVStream *st)
317 AVFrame *picture_ptr;
321 if (frame_count >= STREAM_NB_FRAMES) {
322 /* no more frame to compress. The codec has a latency of a few
323 frames if using B frames, so we get the last frames by
324 passing a NULL picture */
327 if (c->pix_fmt != PIX_FMT_YUV420P) {
328 /* as we only generate a YUV420P picture, we must convert it
329 to the codec pixel format if needed */
330 fill_yuv_image(tmp_picture, frame_count, c->width, c->height);
331 img_convert((AVPicture *)picture, c->pix_fmt,
332 (AVPicture *)tmp_picture, PIX_FMT_YUV420P,
333 c->width, c->height);
335 fill_yuv_image(picture, frame_count, c->width, c->height);
337 picture_ptr = picture;
341 if (oc->oformat->flags & AVFMT_RAWPICTURE) {
342 /* raw video case. The API will change slightly in the near
345 av_init_packet(&pkt);
347 pkt.flags |= PKT_FLAG_KEY;
348 pkt.stream_index= st->index;
349 pkt.data= (uint8_t *)picture_ptr;
350 pkt.size= sizeof(AVPicture);
352 ret = av_write_frame(oc, &pkt);
354 /* encode the image */
355 out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture_ptr);
356 /* if zero size, it means the image was buffered */
359 av_init_packet(&pkt);
361 pkt.pts= c->coded_frame->pts;
362 if(c->coded_frame->key_frame)
363 pkt.flags |= PKT_FLAG_KEY;
364 pkt.stream_index= st->index;
365 pkt.data= video_outbuf;
368 /* write the compressed frame in the media file */
369 ret = av_write_frame(oc, &pkt);
375 fprintf(stderr, "Error while writing video frame\n");
381 void close_video(AVFormatContext *oc, AVStream *st)
383 avcodec_close(&st->codec);
384 av_free(picture->data[0]);
387 av_free(tmp_picture->data[0]);
388 av_free(tmp_picture);
390 av_free(video_outbuf);
393 /**************************************************************/
394 /* media file output */
396 int main(int argc, char **argv)
398 const char *filename;
401 AVStream *audio_st, *video_st;
402 double audio_pts, video_pts;
405 /* initialize libavcodec, and register all codecs and formats */
409 printf("usage: %s output_file\n"
410 "API example program to output a media file with libavformat.\n"
411 "The output format is automatically guessed according to the file extension.\n"
412 "Raw images can also be output by using '%%d' in the filename\n"
419 /* auto detect the output format from the name. default is
421 fmt = guess_format(NULL, filename, NULL);
423 printf("Could not deduce output format from file extension: using MPEG.\n");
424 fmt = guess_format("mpeg", NULL, NULL);
427 fprintf(stderr, "Could not find suitable output format\n");
431 /* allocate the output media context */
432 oc = av_alloc_format_context();
434 fprintf(stderr, "Memory error\n");
438 snprintf(oc->filename, sizeof(oc->filename), "%s", filename);
440 /* add the audio and video streams using the default format codecs
441 and initialize the codecs */
444 if (fmt->video_codec != CODEC_ID_NONE) {
445 video_st = add_video_stream(oc, fmt->video_codec);
447 if (fmt->audio_codec != CODEC_ID_NONE) {
448 audio_st = add_audio_stream(oc, fmt->audio_codec);
451 /* set the output parameters (must be done even if no
453 if (av_set_parameters(oc, NULL) < 0) {
454 fprintf(stderr, "Invalid output format parameters\n");
458 dump_format(oc, 0, filename, 1);
460 /* now that all the parameters are set, we can open the audio and
461 video codecs and allocate the necessary encode buffers */
463 open_video(oc, video_st);
465 open_audio(oc, audio_st);
467 /* open the output file, if needed */
468 if (!(fmt->flags & AVFMT_NOFILE)) {
469 if (url_fopen(&oc->pb, filename, URL_WRONLY) < 0) {
470 fprintf(stderr, "Could not open '%s'\n", filename);
475 /* write the stream header, if any */
479 /* compute current audio and video time */
481 audio_pts = (double)audio_st->pts.val * audio_st->time_base.num / audio_st->time_base.den;
486 video_pts = (double)video_st->pts.val * video_st->time_base.num / video_st->time_base.den;
490 if ((!audio_st || audio_pts >= STREAM_DURATION) &&
491 (!video_st || video_pts >= STREAM_DURATION))
494 /* write interleaved audio and video frames */
495 if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
496 write_audio_frame(oc, audio_st);
498 write_video_frame(oc, video_st);
502 /* close each codec */
504 close_video(oc, video_st);
506 close_audio(oc, audio_st);
508 /* write the trailer, if any */
509 av_write_trailer(oc);
511 /* free the streams */
512 for(i = 0; i < oc->nb_streams; i++) {
513 av_freep(&oc->streams[i]);
516 if (!(fmt->flags & AVFMT_NOFILE)) {
517 /* close the output file */
521 /* free the stream */