2 * Copyright (c) 2003 Fabrice Bellard
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25 * libavformat API example.
27 * Output a media file in any supported libavformat format.
28 * The default codecs are used.
36 #include "libavutil/mathematics.h"
37 #include "libavformat/avformat.h"
38 #include "libswscale/swscale.h"
42 /* 5 seconds stream duration */
43 #define STREAM_DURATION 200.0
44 #define STREAM_FRAME_RATE 25 /* 25 images/s */
45 #define STREAM_NB_FRAMES ((int)(STREAM_DURATION * STREAM_FRAME_RATE))
46 #define STREAM_PIX_FMT PIX_FMT_YUV420P /* default pix_fmt */
48 static int sws_flags = SWS_BICUBIC;
50 /**************************************************************/
53 float t, tincr, tincr2;
55 uint8_t *audio_outbuf;
56 int audio_outbuf_size;
57 int audio_input_frame_size;
60 * add an audio output stream
62 static AVStream *add_audio_stream(AVFormatContext *oc, enum CodecID codec_id)
67 st = avformat_new_stream(oc, NULL);
69 fprintf(stderr, "Could not alloc stream\n");
75 c->codec_id = codec_id;
76 c->codec_type = AVMEDIA_TYPE_AUDIO;
78 /* put sample parameters */
79 c->sample_fmt = AV_SAMPLE_FMT_S16;
81 c->sample_rate = 44100;
84 // some formats want stream headers to be separate
85 if (oc->oformat->flags & AVFMT_GLOBALHEADER)
86 c->flags |= CODEC_FLAG_GLOBAL_HEADER;
91 static void open_audio(AVFormatContext *oc, AVStream *st)
98 /* find the audio encoder */
99 codec = avcodec_find_encoder(c->codec_id);
101 fprintf(stderr, "codec not found\n");
106 if (avcodec_open(c, codec) < 0) {
107 fprintf(stderr, "could not open codec\n");
111 /* init signal generator */
113 tincr = 2 * M_PI * 110.0 / c->sample_rate;
114 /* increment frequency by 110 Hz per second */
115 tincr2 = 2 * M_PI * 110.0 / c->sample_rate / c->sample_rate;
117 audio_outbuf_size = 10000;
118 audio_outbuf = av_malloc(audio_outbuf_size);
120 /* ugly hack for PCM codecs (will be removed ASAP with new PCM
121 support to compute the input frame size in samples */
122 if (c->frame_size <= 1) {
123 audio_input_frame_size = audio_outbuf_size / c->channels;
124 switch(st->codec->codec_id) {
125 case CODEC_ID_PCM_S16LE:
126 case CODEC_ID_PCM_S16BE:
127 case CODEC_ID_PCM_U16LE:
128 case CODEC_ID_PCM_U16BE:
129 audio_input_frame_size >>= 1;
135 audio_input_frame_size = c->frame_size;
137 samples = av_malloc(audio_input_frame_size * 2 * c->channels);
140 /* prepare a 16 bit dummy audio frame of 'frame_size' samples and
141 'nb_channels' channels */
142 static void get_audio_frame(int16_t *samples, int frame_size, int nb_channels)
148 for (j = 0; j < frame_size; j++) {
149 v = (int)(sin(t) * 10000);
150 for(i = 0; i < nb_channels; i++)
157 static void write_audio_frame(AVFormatContext *oc, AVStream *st)
161 av_init_packet(&pkt);
165 get_audio_frame(samples, audio_input_frame_size, c->channels);
167 pkt.size = avcodec_encode_audio(c, audio_outbuf, audio_outbuf_size, samples);
169 if (c->coded_frame && c->coded_frame->pts != AV_NOPTS_VALUE)
170 pkt.pts= av_rescale_q(c->coded_frame->pts, c->time_base, st->time_base);
171 pkt.flags |= AV_PKT_FLAG_KEY;
172 pkt.stream_index = st->index;
173 pkt.data = audio_outbuf;
175 /* write the compressed frame in the media file */
176 if (av_interleaved_write_frame(oc, &pkt) != 0) {
177 fprintf(stderr, "Error while writing audio frame\n");
182 static void close_audio(AVFormatContext *oc, AVStream *st)
184 avcodec_close(st->codec);
187 av_free(audio_outbuf);
190 /**************************************************************/
193 AVFrame *picture, *tmp_picture;
194 uint8_t *video_outbuf;
195 int frame_count, video_outbuf_size;
197 /* add a video output stream */
198 static AVStream *add_video_stream(AVFormatContext *oc, enum CodecID codec_id)
203 st = avformat_new_stream(oc, NULL);
205 fprintf(stderr, "Could not alloc stream\n");
210 c->codec_id = codec_id;
211 c->codec_type = AVMEDIA_TYPE_VIDEO;
213 /* put sample parameters */
214 c->bit_rate = 400000;
215 /* resolution must be a multiple of two */
218 /* time base: this is the fundamental unit of time (in seconds) in terms
219 of which frame timestamps are represented. for fixed-fps content,
220 timebase should be 1/framerate and timestamp increments should be
222 c->time_base.den = STREAM_FRAME_RATE;
223 c->time_base.num = 1;
224 c->gop_size = 12; /* emit one intra frame every twelve frames at most */
225 c->pix_fmt = STREAM_PIX_FMT;
226 if (c->codec_id == CODEC_ID_MPEG2VIDEO) {
227 /* just for testing, we also add B frames */
230 if (c->codec_id == CODEC_ID_MPEG1VIDEO){
231 /* Needed to avoid using macroblocks in which some coeffs overflow.
232 This does not happen with normal video, it just happens here as
233 the motion of the chroma plane does not match the luma plane. */
236 // some formats want stream headers to be separate
237 if (oc->oformat->flags & AVFMT_GLOBALHEADER)
238 c->flags |= CODEC_FLAG_GLOBAL_HEADER;
243 static AVFrame *alloc_picture(enum PixelFormat pix_fmt, int width, int height)
246 uint8_t *picture_buf;
249 picture = avcodec_alloc_frame();
252 size = avpicture_get_size(pix_fmt, width, height);
253 picture_buf = av_malloc(size);
258 avpicture_fill((AVPicture *)picture, picture_buf,
259 pix_fmt, width, height);
263 static void open_video(AVFormatContext *oc, AVStream *st)
270 /* find the video encoder */
271 codec = avcodec_find_encoder(c->codec_id);
273 fprintf(stderr, "codec not found\n");
278 if (avcodec_open(c, codec) < 0) {
279 fprintf(stderr, "could not open codec\n");
284 if (!(oc->oformat->flags & AVFMT_RAWPICTURE)) {
285 /* allocate output buffer */
286 /* XXX: API change will be done */
287 /* buffers passed into lav* can be allocated any way you prefer,
288 as long as they're aligned enough for the architecture, and
289 they're freed appropriately (such as using av_free for buffers
290 allocated with av_malloc) */
291 video_outbuf_size = 200000;
292 video_outbuf = av_malloc(video_outbuf_size);
295 /* allocate the encoded raw picture */
296 picture = alloc_picture(c->pix_fmt, c->width, c->height);
298 fprintf(stderr, "Could not allocate picture\n");
302 /* if the output format is not YUV420P, then a temporary YUV420P
303 picture is needed too. It is then converted to the required
306 if (c->pix_fmt != PIX_FMT_YUV420P) {
307 tmp_picture = alloc_picture(PIX_FMT_YUV420P, c->width, c->height);
309 fprintf(stderr, "Could not allocate temporary picture\n");
315 /* prepare a dummy image */
316 static void fill_yuv_image(AVFrame *pict, int frame_index, int width, int height)
323 for (y = 0; y < height; y++) {
324 for (x = 0; x < width; x++) {
325 pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
330 for (y = 0; y < height/2; y++) {
331 for (x = 0; x < width/2; x++) {
332 pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
333 pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
338 static void write_video_frame(AVFormatContext *oc, AVStream *st)
342 static struct SwsContext *img_convert_ctx;
346 if (frame_count >= STREAM_NB_FRAMES) {
347 /* no more frame to compress. The codec has a latency of a few
348 frames if using B frames, so we get the last frames by
349 passing the same picture again */
351 if (c->pix_fmt != PIX_FMT_YUV420P) {
352 /* as we only generate a YUV420P picture, we must convert it
353 to the codec pixel format if needed */
354 if (img_convert_ctx == NULL) {
355 img_convert_ctx = sws_getContext(c->width, c->height,
359 sws_flags, NULL, NULL, NULL);
360 if (img_convert_ctx == NULL) {
361 fprintf(stderr, "Cannot initialize the conversion context\n");
365 fill_yuv_image(tmp_picture, frame_count, c->width, c->height);
366 sws_scale(img_convert_ctx, tmp_picture->data, tmp_picture->linesize,
367 0, c->height, picture->data, picture->linesize);
369 fill_yuv_image(picture, frame_count, c->width, c->height);
374 if (oc->oformat->flags & AVFMT_RAWPICTURE) {
375 /* raw video case. The API will change slightly in the near
378 av_init_packet(&pkt);
380 pkt.flags |= AV_PKT_FLAG_KEY;
381 pkt.stream_index = st->index;
382 pkt.data = (uint8_t *)picture;
383 pkt.size = sizeof(AVPicture);
385 ret = av_interleaved_write_frame(oc, &pkt);
387 /* encode the image */
388 out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture);
389 /* if zero size, it means the image was buffered */
392 av_init_packet(&pkt);
394 if (c->coded_frame->pts != AV_NOPTS_VALUE)
395 pkt.pts= av_rescale_q(c->coded_frame->pts, c->time_base, st->time_base);
396 if(c->coded_frame->key_frame)
397 pkt.flags |= AV_PKT_FLAG_KEY;
398 pkt.stream_index = st->index;
399 pkt.data = video_outbuf;
402 /* write the compressed frame in the media file */
403 ret = av_interleaved_write_frame(oc, &pkt);
409 fprintf(stderr, "Error while writing video frame\n");
415 static void close_video(AVFormatContext *oc, AVStream *st)
417 avcodec_close(st->codec);
418 av_free(picture->data[0]);
421 av_free(tmp_picture->data[0]);
422 av_free(tmp_picture);
424 av_free(video_outbuf);
427 /**************************************************************/
428 /* media file output */
430 int main(int argc, char **argv)
432 const char *filename;
435 AVStream *audio_st, *video_st;
436 double audio_pts, video_pts;
439 /* initialize libavcodec, and register all codecs and formats */
443 printf("usage: %s output_file\n"
444 "API example program to output a media file with libavformat.\n"
445 "The output format is automatically guessed according to the file extension.\n"
446 "Raw images can also be output by using '%%d' in the filename\n"
453 /* allocate the output media context */
454 avformat_alloc_output_context2(&oc, NULL, NULL, filename);
456 printf("Could not deduce output format from file extension: using MPEG.\n");
457 avformat_alloc_output_context2(&oc, NULL, "mpeg", filename);
464 /* add the audio and video streams using the default format codecs
465 and initialize the codecs */
468 if (fmt->video_codec != CODEC_ID_NONE) {
469 video_st = add_video_stream(oc, fmt->video_codec);
471 if (fmt->audio_codec != CODEC_ID_NONE) {
472 audio_st = add_audio_stream(oc, fmt->audio_codec);
475 av_dump_format(oc, 0, filename, 1);
477 /* now that all the parameters are set, we can open the audio and
478 video codecs and allocate the necessary encode buffers */
480 open_video(oc, video_st);
482 open_audio(oc, audio_st);
484 /* open the output file, if needed */
485 if (!(fmt->flags & AVFMT_NOFILE)) {
486 if (avio_open(&oc->pb, filename, AVIO_FLAG_WRITE) < 0) {
487 fprintf(stderr, "Could not open '%s'\n", filename);
492 /* write the stream header, if any */
496 /* compute current audio and video time */
498 audio_pts = (double)audio_st->pts.val * audio_st->time_base.num / audio_st->time_base.den;
503 video_pts = (double)video_st->pts.val * video_st->time_base.num / video_st->time_base.den;
507 if ((!audio_st || audio_pts >= STREAM_DURATION) &&
508 (!video_st || video_pts >= STREAM_DURATION))
511 /* write interleaved audio and video frames */
512 if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
513 write_audio_frame(oc, audio_st);
515 write_video_frame(oc, video_st);
519 /* write the trailer, if any. the trailer must be written
520 * before you close the CodecContexts open when you wrote the
521 * header; otherwise write_trailer may try to use memory that
522 * was freed on av_codec_close() */
523 av_write_trailer(oc);
525 /* close each codec */
527 close_video(oc, video_st);
529 close_audio(oc, audio_st);
531 /* free the streams */
532 for(i = 0; i < oc->nb_streams; i++) {
533 av_freep(&oc->streams[i]->codec);
534 av_freep(&oc->streams[i]);
537 if (!(fmt->flags & AVFMT_NOFILE)) {
538 /* close the output file */
542 /* free the stream */