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 #include "libavformat/avformat.h"
31 #include "libswscale/swscale.h"
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))
39 #define STREAM_PIX_FMT PIX_FMT_YUV420P /* default pix_fmt */
41 static int sws_flags = SWS_BICUBIC;
43 /**************************************************************/
46 float t, tincr, tincr2;
48 uint8_t *audio_outbuf;
49 int audio_outbuf_size;
50 int audio_input_frame_size;
53 * add an audio output stream
55 static AVStream *add_audio_stream(AVFormatContext *oc, enum CodecID codec_id)
60 st = av_new_stream(oc, 1);
62 fprintf(stderr, "Could not alloc stream\n");
67 c->codec_id = codec_id;
68 c->codec_type = AVMEDIA_TYPE_AUDIO;
70 /* put sample parameters */
71 c->sample_fmt = SAMPLE_FMT_S16;
73 c->sample_rate = 44100;
76 // some formats want stream headers to be separate
77 if(oc->oformat->flags & AVFMT_GLOBALHEADER)
78 c->flags |= CODEC_FLAG_GLOBAL_HEADER;
83 static void open_audio(AVFormatContext *oc, AVStream *st)
90 /* find the audio encoder */
91 codec = avcodec_find_encoder(c->codec_id);
93 fprintf(stderr, "codec not found\n");
98 if (avcodec_open(c, codec) < 0) {
99 fprintf(stderr, "could not open codec\n");
103 /* init signal generator */
105 tincr = 2 * M_PI * 110.0 / c->sample_rate;
106 /* increment frequency by 110 Hz per second */
107 tincr2 = 2 * M_PI * 110.0 / c->sample_rate / c->sample_rate;
109 audio_outbuf_size = 10000;
110 audio_outbuf = av_malloc(audio_outbuf_size);
112 /* ugly hack for PCM codecs (will be removed ASAP with new PCM
113 support to compute the input frame size in samples */
114 if (c->frame_size <= 1) {
115 audio_input_frame_size = audio_outbuf_size / c->channels;
116 switch(st->codec->codec_id) {
117 case CODEC_ID_PCM_S16LE:
118 case CODEC_ID_PCM_S16BE:
119 case CODEC_ID_PCM_U16LE:
120 case CODEC_ID_PCM_U16BE:
121 audio_input_frame_size >>= 1;
127 audio_input_frame_size = c->frame_size;
129 samples = av_malloc(audio_input_frame_size * 2 * c->channels);
132 /* prepare a 16 bit dummy audio frame of 'frame_size' samples and
133 'nb_channels' channels */
134 static void get_audio_frame(int16_t *samples, int frame_size, int nb_channels)
140 for(j=0;j<frame_size;j++) {
141 v = (int)(sin(t) * 10000);
142 for(i = 0; i < nb_channels; i++)
149 static void write_audio_frame(AVFormatContext *oc, AVStream *st)
153 av_init_packet(&pkt);
157 get_audio_frame(samples, audio_input_frame_size, c->channels);
159 pkt.size= avcodec_encode_audio(c, audio_outbuf, audio_outbuf_size, samples);
161 if (c->coded_frame && c->coded_frame->pts != AV_NOPTS_VALUE)
162 pkt.pts= av_rescale_q(c->coded_frame->pts, c->time_base, st->time_base);
163 pkt.flags |= AV_PKT_FLAG_KEY;
164 pkt.stream_index= st->index;
165 pkt.data= audio_outbuf;
167 /* write the compressed frame in the media file */
168 if (av_interleaved_write_frame(oc, &pkt) != 0) {
169 fprintf(stderr, "Error while writing audio frame\n");
174 static void close_audio(AVFormatContext *oc, AVStream *st)
176 avcodec_close(st->codec);
179 av_free(audio_outbuf);
182 /**************************************************************/
185 AVFrame *picture, *tmp_picture;
186 uint8_t *video_outbuf;
187 int frame_count, video_outbuf_size;
189 /* add a video output stream */
190 static AVStream *add_video_stream(AVFormatContext *oc, enum CodecID codec_id)
195 st = av_new_stream(oc, 0);
197 fprintf(stderr, "Could not alloc stream\n");
202 c->codec_id = codec_id;
203 c->codec_type = AVMEDIA_TYPE_VIDEO;
205 /* put sample parameters */
206 c->bit_rate = 400000;
207 /* resolution must be a multiple of two */
210 /* time base: this is the fundamental unit of time (in seconds) in terms
211 of which frame timestamps are represented. for fixed-fps content,
212 timebase should be 1/framerate and timestamp increments should be
214 c->time_base.den = STREAM_FRAME_RATE;
215 c->time_base.num = 1;
216 c->gop_size = 12; /* emit one intra frame every twelve frames at most */
217 c->pix_fmt = STREAM_PIX_FMT;
218 if (c->codec_id == CODEC_ID_MPEG2VIDEO) {
219 /* just for testing, we also add B frames */
222 if (c->codec_id == CODEC_ID_MPEG1VIDEO){
223 /* Needed to avoid using macroblocks in which some coeffs overflow.
224 This does not happen with normal video, it just happens here as
225 the motion of the chroma plane does not match the luma plane. */
228 // some formats want stream headers to be separate
229 if(oc->oformat->flags & AVFMT_GLOBALHEADER)
230 c->flags |= CODEC_FLAG_GLOBAL_HEADER;
235 static AVFrame *alloc_picture(enum PixelFormat pix_fmt, int width, int height)
238 uint8_t *picture_buf;
241 picture = avcodec_alloc_frame();
244 size = avpicture_get_size(pix_fmt, width, height);
245 picture_buf = av_malloc(size);
250 avpicture_fill((AVPicture *)picture, picture_buf,
251 pix_fmt, width, height);
255 static void open_video(AVFormatContext *oc, AVStream *st)
262 /* find the video encoder */
263 codec = avcodec_find_encoder(c->codec_id);
265 fprintf(stderr, "codec not found\n");
270 if (avcodec_open(c, codec) < 0) {
271 fprintf(stderr, "could not open codec\n");
276 if (!(oc->oformat->flags & AVFMT_RAWPICTURE)) {
277 /* allocate output buffer */
278 /* XXX: API change will be done */
279 /* buffers passed into lav* can be allocated any way you prefer,
280 as long as they're aligned enough for the architecture, and
281 they're freed appropriately (such as using av_free for buffers
282 allocated with av_malloc) */
283 video_outbuf_size = 200000;
284 video_outbuf = av_malloc(video_outbuf_size);
287 /* allocate the encoded raw picture */
288 picture = alloc_picture(c->pix_fmt, c->width, c->height);
290 fprintf(stderr, "Could not allocate picture\n");
294 /* if the output format is not YUV420P, then a temporary YUV420P
295 picture is needed too. It is then converted to the required
298 if (c->pix_fmt != PIX_FMT_YUV420P) {
299 tmp_picture = alloc_picture(PIX_FMT_YUV420P, c->width, c->height);
301 fprintf(stderr, "Could not allocate temporary picture\n");
307 /* prepare a dummy image */
308 static void fill_yuv_image(AVFrame *pict, int frame_index, int width, int height)
315 for(y=0;y<height;y++) {
316 for(x=0;x<width;x++) {
317 pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
322 for(y=0;y<height/2;y++) {
323 for(x=0;x<width/2;x++) {
324 pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
325 pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
330 static void write_video_frame(AVFormatContext *oc, AVStream *st)
334 static struct SwsContext *img_convert_ctx;
338 if (frame_count >= STREAM_NB_FRAMES) {
339 /* no more frame to compress. The codec has a latency of a few
340 frames if using B frames, so we get the last frames by
341 passing the same picture again */
343 if (c->pix_fmt != PIX_FMT_YUV420P) {
344 /* as we only generate a YUV420P picture, we must convert it
345 to the codec pixel format if needed */
346 if (img_convert_ctx == NULL) {
347 img_convert_ctx = sws_getContext(c->width, c->height,
351 sws_flags, NULL, NULL, NULL);
352 if (img_convert_ctx == NULL) {
353 fprintf(stderr, "Cannot initialize the conversion context\n");
357 fill_yuv_image(tmp_picture, frame_count, c->width, c->height);
358 sws_scale(img_convert_ctx, tmp_picture->data, tmp_picture->linesize,
359 0, c->height, picture->data, picture->linesize);
361 fill_yuv_image(picture, frame_count, c->width, c->height);
366 if (oc->oformat->flags & AVFMT_RAWPICTURE) {
367 /* raw video case. The API will change slightly in the near
370 av_init_packet(&pkt);
372 pkt.flags |= AV_PKT_FLAG_KEY;
373 pkt.stream_index= st->index;
374 pkt.data= (uint8_t *)picture;
375 pkt.size= sizeof(AVPicture);
377 ret = av_interleaved_write_frame(oc, &pkt);
379 /* encode the image */
380 out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture);
381 /* if zero size, it means the image was buffered */
384 av_init_packet(&pkt);
386 if (c->coded_frame->pts != AV_NOPTS_VALUE)
387 pkt.pts= av_rescale_q(c->coded_frame->pts, c->time_base, st->time_base);
388 if(c->coded_frame->key_frame)
389 pkt.flags |= AV_PKT_FLAG_KEY;
390 pkt.stream_index= st->index;
391 pkt.data= video_outbuf;
394 /* write the compressed frame in the media file */
395 ret = av_interleaved_write_frame(oc, &pkt);
401 fprintf(stderr, "Error while writing video frame\n");
407 static void close_video(AVFormatContext *oc, AVStream *st)
409 avcodec_close(st->codec);
410 av_free(picture->data[0]);
413 av_free(tmp_picture->data[0]);
414 av_free(tmp_picture);
416 av_free(video_outbuf);
419 /**************************************************************/
420 /* media file output */
422 int main(int argc, char **argv)
424 const char *filename;
427 AVStream *audio_st, *video_st;
428 double audio_pts, video_pts;
431 /* initialize libavcodec, and register all codecs and formats */
435 printf("usage: %s output_file\n"
436 "API example program to output a media file with libavformat.\n"
437 "The output format is automatically guessed according to the file extension.\n"
438 "Raw images can also be output by using '%%d' in the filename\n"
445 /* auto detect the output format from the name. default is
447 fmt = av_guess_format(NULL, filename, NULL);
449 printf("Could not deduce output format from file extension: using MPEG.\n");
450 fmt = av_guess_format("mpeg", NULL, NULL);
453 fprintf(stderr, "Could not find suitable output format\n");
457 /* allocate the output media context */
458 oc = avformat_alloc_context();
460 fprintf(stderr, "Memory error\n");
464 snprintf(oc->filename, sizeof(oc->filename), "%s", filename);
466 /* add the audio and video streams using the default format codecs
467 and initialize the codecs */
470 if (fmt->video_codec != CODEC_ID_NONE) {
471 video_st = add_video_stream(oc, fmt->video_codec);
473 if (fmt->audio_codec != CODEC_ID_NONE) {
474 audio_st = add_audio_stream(oc, fmt->audio_codec);
477 /* set the output parameters (must be done even if no
479 if (av_set_parameters(oc, NULL) < 0) {
480 fprintf(stderr, "Invalid output format parameters\n");
484 dump_format(oc, 0, filename, 1);
486 /* now that all the parameters are set, we can open the audio and
487 video codecs and allocate the necessary encode buffers */
489 open_video(oc, video_st);
491 open_audio(oc, audio_st);
493 /* open the output file, if needed */
494 if (!(fmt->flags & AVFMT_NOFILE)) {
495 if (url_fopen(&oc->pb, filename, URL_WRONLY) < 0) {
496 fprintf(stderr, "Could not open '%s'\n", filename);
501 /* write the stream header, if any */
505 /* compute current audio and video time */
507 audio_pts = (double)audio_st->pts.val * audio_st->time_base.num / audio_st->time_base.den;
512 video_pts = (double)video_st->pts.val * video_st->time_base.num / video_st->time_base.den;
516 if ((!audio_st || audio_pts >= STREAM_DURATION) &&
517 (!video_st || video_pts >= STREAM_DURATION))
520 /* write interleaved audio and video frames */
521 if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
522 write_audio_frame(oc, audio_st);
524 write_video_frame(oc, video_st);
528 /* write the trailer, if any. the trailer must be written
529 * before you close the CodecContexts open when you wrote the
530 * header; otherwise write_trailer may try to use memory that
531 * was freed on av_codec_close() */
532 av_write_trailer(oc);
534 /* close each codec */
536 close_video(oc, video_st);
538 close_audio(oc, audio_st);
540 /* free the streams */
541 for(i = 0; i < oc->nb_streams; i++) {
542 av_freep(&oc->streams[i]->codec);
543 av_freep(&oc->streams[i]);
546 if (!(fmt->flags & AVFMT_NOFILE)) {
547 /* close the output file */
551 /* free the stream */