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 /* 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 void write_audio_frame(AVFormatContext *oc, AVStream *st)
126 for(j=0;j<audio_input_frame_size;j++) {
127 samples[2*j] = (int)(sin(t) * 10000);
128 samples[2*j+1] = samples[2*j];
133 out_size = avcodec_encode_audio(c, audio_outbuf, audio_outbuf_size, samples);
135 /* write the compressed frame in the media file */
136 if (av_write_frame(oc, st->index, audio_outbuf, out_size) != 0) {
137 fprintf(stderr, "Error while writing audio frame\n");
142 void close_audio(AVFormatContext *oc, AVStream *st)
144 avcodec_close(&st->codec);
147 av_free(audio_outbuf);
150 /**************************************************************/
153 AVFrame *picture, *tmp_picture;
154 uint8_t *video_outbuf;
155 int frame_count, video_outbuf_size;
157 /* add a video output stream */
158 AVStream *add_video_stream(AVFormatContext *oc, int codec_id)
163 st = av_new_stream(oc, 0);
165 fprintf(stderr, "Could not alloc stream\n");
170 c->codec_id = codec_id;
171 c->codec_type = CODEC_TYPE_VIDEO;
173 /* put sample parameters */
174 c->bit_rate = 400000;
175 /* resolution must be a multiple of two */
178 /* frames per second */
180 c->frame_rate_base= 1;
181 c->gop_size = 12; /* emit one intra frame every twelve frames */
186 AVFrame *alloc_picture(int pix_fmt, int width, int height)
189 uint8_t *picture_buf;
192 picture = avcodec_alloc_frame();
195 size = avpicture_get_size(pix_fmt, width, height);
196 picture_buf = malloc(size);
201 avpicture_fill((AVPicture *)picture, picture_buf,
202 pix_fmt, width, height);
206 void open_video(AVFormatContext *oc, AVStream *st)
213 /* find the video encoder */
214 codec = avcodec_find_encoder(c->codec_id);
216 fprintf(stderr, "codec not found\n");
221 if (avcodec_open(c, codec) < 0) {
222 fprintf(stderr, "could not open codec\n");
227 if (!(oc->oformat->flags & AVFMT_RAWPICTURE)) {
228 /* allocate output buffer */
229 /* XXX: API change will be done */
230 video_outbuf_size = 200000;
231 video_outbuf = malloc(video_outbuf_size);
234 /* allocate the encoded raw picture */
235 picture = alloc_picture(c->pix_fmt, c->width, c->height);
237 fprintf(stderr, "Could not allocate picture\n");
241 /* if the output format is not YUV420P, then a temporary YUV420P
242 picture is needed too. It is then converted to the required
245 if (c->pix_fmt != PIX_FMT_YUV420P) {
246 tmp_picture = alloc_picture(PIX_FMT_YUV420P, c->width, c->height);
248 fprintf(stderr, "Could not allocate temporary picture\n");
254 /* prepare a dummy image */
255 void fill_yuv_image(AVFrame *pict, int frame_index, int width, int height)
262 for(y=0;y<height;y++) {
263 for(x=0;x<width;x++) {
264 pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
269 for(y=0;y<height/2;y++) {
270 for(x=0;x<width/2;x++) {
271 pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
272 pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
277 void write_video_frame(AVFormatContext *oc, AVStream *st)
284 if (c->pix_fmt != PIX_FMT_YUV420P) {
285 /* as we only generate a YUV420P picture, we must convert it
286 to the codec pixel format if needed */
287 fill_yuv_image(tmp_picture, frame_count, c->width, c->height);
288 img_convert((AVPicture *)picture, c->pix_fmt,
289 (AVPicture *)tmp_picture, PIX_FMT_YUV420P,
290 c->width, c->height);
292 fill_yuv_image(picture, frame_count, c->width, c->height);
296 if (oc->oformat->flags & AVFMT_RAWPICTURE) {
297 /* raw video case. The API will change slightly in the near
299 ret = av_write_frame(oc, st->index,
300 (uint8_t *)picture, sizeof(AVPicture));
302 /* encode the image */
303 out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture);
305 /* write the compressed frame in the media file */
306 ret = av_write_frame(oc, st->index, video_outbuf, out_size);
309 fprintf(stderr, "Error while writing video frame\n");
315 void close_video(AVFormatContext *oc, AVStream *st)
317 avcodec_close(&st->codec);
318 av_free(picture->data[0]);
321 av_free(tmp_picture->data[0]);
322 av_free(tmp_picture);
324 av_free(video_outbuf);
327 /**************************************************************/
328 /* media file output */
330 int main(int argc, char **argv)
332 const char *filename;
335 AVStream *audio_st, *video_st;
336 double audio_pts, video_pts;
339 /* initialize libavcodec, and register all codecs and formats */
343 printf("usage: %s output_file\n"
344 "API example program to output a media file with libavformat.\n"
345 "The output format is automatically guessed according to the file extension.\n"
346 "Raw images can also be output by using '%%d' in the filename\n"
353 /* auto detect the output format from the name. default is
355 fmt = guess_format(NULL, filename, NULL);
357 printf("Could not deduce output format from file extension: using MPEG.\n");
358 fmt = guess_format("mpeg", NULL, NULL);
361 fprintf(stderr, "Could not find suitable output format\n");
365 /* allocate the output media context */
366 oc = av_mallocz(sizeof(AVFormatContext));
368 fprintf(stderr, "Memory error\n");
372 snprintf(oc->filename, sizeof(oc->filename), "%s", filename);
374 /* add the audio and video streams using the default format codecs
375 and initialize the codecs */
378 if (fmt->video_codec != CODEC_ID_NONE) {
379 video_st = add_video_stream(oc, fmt->video_codec);
381 if (fmt->audio_codec != CODEC_ID_NONE) {
382 audio_st = add_audio_stream(oc, fmt->audio_codec);
385 /* set the output parameters (must be done even if no
387 if (av_set_parameters(oc, NULL) < 0) {
388 fprintf(stderr, "Invalid output format parameters\n");
392 dump_format(oc, 0, filename, 1);
394 /* now that all the parameters are set, we can open the audio and
395 video codecs and allocate the necessary encode buffers */
397 open_video(oc, video_st);
399 open_audio(oc, audio_st);
401 /* open the output file, if needed */
402 if (!(fmt->flags & AVFMT_NOFILE)) {
403 if (url_fopen(&oc->pb, filename, URL_WRONLY) < 0) {
404 fprintf(stderr, "Could not open '%s'\n", filename);
409 /* write the stream header, if any */
413 /* compute current audio and video time */
415 audio_pts = (double)audio_st->pts.val * oc->pts_num / oc->pts_den;
420 video_pts = (double)video_st->pts.val * oc->pts_num / oc->pts_den;
424 if ((!audio_st || audio_pts >= STREAM_DURATION) &&
425 (!video_st || video_pts >= STREAM_DURATION))
428 /* write interleaved audio and video frames */
429 if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
430 write_audio_frame(oc, audio_st);
432 write_video_frame(oc, video_st);
436 /* close each codec */
438 close_video(oc, video_st);
440 close_audio(oc, audio_st);
442 /* write the trailer, if any */
443 av_write_trailer(oc);
445 /* free the streams */
446 for(i = 0; i < oc->nb_streams; i++) {
447 av_freep(&oc->streams[i]);
450 if (!(fmt->flags & AVFMT_NOFILE)) {
451 /* close the output file */
455 /* free the stream */