2 * Copyright (c) 2003 Fabrice Bellard
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25 * Libavformat API example: Output a media file in any supported
26 * libavformat format. The default codecs are used.
34 #include "libavformat/avformat.h"
35 #include "libswscale/swscale.h"
39 /* 5 seconds stream duration */
40 #define STREAM_DURATION 5.0
41 #define STREAM_FRAME_RATE 25 /* 25 images/s */
42 #define STREAM_NB_FRAMES ((int)(STREAM_DURATION * STREAM_FRAME_RATE))
43 #define STREAM_PIX_FMT PIX_FMT_YUV420P /* default pix_fmt */
45 static int sws_flags = SWS_BICUBIC;
47 /**************************************************************/
50 float t, tincr, tincr2;
52 uint8_t *audio_outbuf;
53 int audio_outbuf_size;
54 int audio_input_frame_size;
57 * add an audio output stream
59 static AVStream *add_audio_stream(AVFormatContext *oc, enum CodecID codec_id)
64 st = av_new_stream(oc, 1);
66 fprintf(stderr, "Could not alloc stream\n");
71 c->codec_id = codec_id;
72 c->codec_type = AVMEDIA_TYPE_AUDIO;
74 /* put sample parameters */
75 c->sample_fmt = AV_SAMPLE_FMT_S16;
77 c->sample_rate = 44100;
80 // some formats want stream headers to be separate
81 if(oc->oformat->flags & AVFMT_GLOBALHEADER)
82 c->flags |= CODEC_FLAG_GLOBAL_HEADER;
87 static void open_audio(AVFormatContext *oc, AVStream *st)
94 /* find the audio encoder */
95 codec = avcodec_find_encoder(c->codec_id);
97 fprintf(stderr, "codec not found\n");
102 if (avcodec_open(c, codec) < 0) {
103 fprintf(stderr, "could not open codec\n");
107 /* init signal generator */
109 tincr = 2 * M_PI * 110.0 / c->sample_rate;
110 /* increment frequency by 110 Hz per second */
111 tincr2 = 2 * M_PI * 110.0 / c->sample_rate / c->sample_rate;
113 audio_outbuf_size = 10000;
114 audio_outbuf = av_malloc(audio_outbuf_size);
116 /* ugly hack for PCM codecs (will be removed ASAP with new PCM
117 support to compute the input frame size in samples */
118 if (c->frame_size <= 1) {
119 audio_input_frame_size = audio_outbuf_size / c->channels;
120 switch(st->codec->codec_id) {
121 case CODEC_ID_PCM_S16LE:
122 case CODEC_ID_PCM_S16BE:
123 case CODEC_ID_PCM_U16LE:
124 case CODEC_ID_PCM_U16BE:
125 audio_input_frame_size >>= 1;
131 audio_input_frame_size = c->frame_size;
133 samples = av_malloc(audio_input_frame_size * 2 * c->channels);
136 /* prepare a 16 bit dummy audio frame of 'frame_size' samples and
137 'nb_channels' channels */
138 static void get_audio_frame(int16_t *samples, int frame_size, int nb_channels)
144 for(j=0;j<frame_size;j++) {
145 v = (int)(sin(t) * 10000);
146 for(i = 0; i < nb_channels; i++)
153 static void write_audio_frame(AVFormatContext *oc, AVStream *st)
157 av_init_packet(&pkt);
161 get_audio_frame(samples, audio_input_frame_size, c->channels);
163 pkt.size= avcodec_encode_audio(c, audio_outbuf, audio_outbuf_size, samples);
165 if (c->coded_frame && c->coded_frame->pts != AV_NOPTS_VALUE)
166 pkt.pts= av_rescale_q(c->coded_frame->pts, c->time_base, st->time_base);
167 pkt.flags |= AV_PKT_FLAG_KEY;
168 pkt.stream_index= st->index;
169 pkt.data= audio_outbuf;
171 /* write the compressed frame in the media file */
172 if (av_interleaved_write_frame(oc, &pkt) != 0) {
173 fprintf(stderr, "Error while writing audio frame\n");
178 static void close_audio(AVFormatContext *oc, AVStream *st)
180 avcodec_close(st->codec);
183 av_free(audio_outbuf);
186 /**************************************************************/
189 AVFrame *picture, *tmp_picture;
190 uint8_t *video_outbuf;
191 int frame_count, video_outbuf_size;
193 /* add a video output stream */
194 static AVStream *add_video_stream(AVFormatContext *oc, enum CodecID codec_id)
199 st = av_new_stream(oc, 0);
201 fprintf(stderr, "Could not alloc stream\n");
206 c->codec_id = codec_id;
207 c->codec_type = AVMEDIA_TYPE_VIDEO;
209 /* put sample parameters */
210 c->bit_rate = 400000;
211 /* resolution must be a multiple of two */
214 /* time base: this is the fundamental unit of time (in seconds) in terms
215 of which frame timestamps are represented. for fixed-fps content,
216 timebase should be 1/framerate and timestamp increments should be
218 c->time_base.den = STREAM_FRAME_RATE;
219 c->time_base.num = 1;
220 c->gop_size = 12; /* emit one intra frame every twelve frames at most */
221 c->pix_fmt = STREAM_PIX_FMT;
222 if (c->codec_id == CODEC_ID_MPEG2VIDEO) {
223 /* just for testing, we also add B frames */
226 if (c->codec_id == CODEC_ID_MPEG1VIDEO){
227 /* Needed to avoid using macroblocks in which some coeffs overflow.
228 This does not happen with normal video, it just happens here as
229 the motion of the chroma plane does not match the luma plane. */
232 // some formats want stream headers to be separate
233 if(oc->oformat->flags & AVFMT_GLOBALHEADER)
234 c->flags |= CODEC_FLAG_GLOBAL_HEADER;
239 static AVFrame *alloc_picture(enum PixelFormat pix_fmt, int width, int height)
242 uint8_t *picture_buf;
245 picture = avcodec_alloc_frame();
248 size = avpicture_get_size(pix_fmt, width, height);
249 picture_buf = av_malloc(size);
254 avpicture_fill((AVPicture *)picture, picture_buf,
255 pix_fmt, width, height);
259 static void open_video(AVFormatContext *oc, AVStream *st)
266 /* find the video encoder */
267 codec = avcodec_find_encoder(c->codec_id);
269 fprintf(stderr, "codec not found\n");
274 if (avcodec_open(c, codec) < 0) {
275 fprintf(stderr, "could not open codec\n");
280 if (!(oc->oformat->flags & AVFMT_RAWPICTURE)) {
281 /* allocate output buffer */
282 /* XXX: API change will be done */
283 /* buffers passed into lav* can be allocated any way you prefer,
284 as long as they're aligned enough for the architecture, and
285 they're freed appropriately (such as using av_free for buffers
286 allocated with av_malloc) */
287 video_outbuf_size = 200000;
288 video_outbuf = av_malloc(video_outbuf_size);
291 /* allocate the encoded raw picture */
292 picture = alloc_picture(c->pix_fmt, c->width, c->height);
294 fprintf(stderr, "Could not allocate picture\n");
298 /* if the output format is not YUV420P, then a temporary YUV420P
299 picture is needed too. It is then converted to the required
302 if (c->pix_fmt != PIX_FMT_YUV420P) {
303 tmp_picture = alloc_picture(PIX_FMT_YUV420P, c->width, c->height);
305 fprintf(stderr, "Could not allocate temporary picture\n");
311 /* prepare a dummy image */
312 static void fill_yuv_image(AVFrame *pict, int frame_index, int width, int height)
319 for(y=0;y<height;y++) {
320 for(x=0;x<width;x++) {
321 pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
326 for(y=0;y<height/2;y++) {
327 for(x=0;x<width/2;x++) {
328 pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
329 pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
334 static void write_video_frame(AVFormatContext *oc, AVStream *st)
338 static struct SwsContext *img_convert_ctx;
342 if (frame_count >= STREAM_NB_FRAMES) {
343 /* no more frame to compress. The codec has a latency of a few
344 frames if using B frames, so we get the last frames by
345 passing the same picture again */
347 if (c->pix_fmt != PIX_FMT_YUV420P) {
348 /* as we only generate a YUV420P picture, we must convert it
349 to the codec pixel format if needed */
350 if (img_convert_ctx == NULL) {
351 img_convert_ctx = sws_getContext(c->width, c->height,
355 sws_flags, NULL, NULL, NULL);
356 if (img_convert_ctx == NULL) {
357 fprintf(stderr, "Cannot initialize the conversion context\n");
361 fill_yuv_image(tmp_picture, frame_count, c->width, c->height);
362 sws_scale(img_convert_ctx, tmp_picture->data, tmp_picture->linesize,
363 0, c->height, picture->data, picture->linesize);
365 fill_yuv_image(picture, frame_count, c->width, c->height);
370 if (oc->oformat->flags & AVFMT_RAWPICTURE) {
371 /* raw video case. The API will change slightly in the near
374 av_init_packet(&pkt);
376 pkt.flags |= AV_PKT_FLAG_KEY;
377 pkt.stream_index= st->index;
378 pkt.data= (uint8_t *)picture;
379 pkt.size= sizeof(AVPicture);
381 ret = av_interleaved_write_frame(oc, &pkt);
383 /* encode the image */
384 out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture);
385 /* if zero size, it means the image was buffered */
388 av_init_packet(&pkt);
390 if (c->coded_frame->pts != AV_NOPTS_VALUE)
391 pkt.pts= av_rescale_q(c->coded_frame->pts, c->time_base, st->time_base);
392 if(c->coded_frame->key_frame)
393 pkt.flags |= AV_PKT_FLAG_KEY;
394 pkt.stream_index= st->index;
395 pkt.data= video_outbuf;
398 /* write the compressed frame in the media file */
399 ret = av_interleaved_write_frame(oc, &pkt);
405 fprintf(stderr, "Error while writing video frame\n");
411 static void close_video(AVFormatContext *oc, AVStream *st)
413 avcodec_close(st->codec);
414 av_free(picture->data[0]);
417 av_free(tmp_picture->data[0]);
418 av_free(tmp_picture);
420 av_free(video_outbuf);
423 /**************************************************************/
424 /* media file output */
426 int main(int argc, char **argv)
428 const char *filename;
431 AVStream *audio_st, *video_st;
432 double audio_pts, video_pts;
435 /* initialize libavcodec, and register all codecs and formats */
439 printf("usage: %s output_file\n"
440 "API example program to output a media file with libavformat.\n"
441 "The output format is automatically guessed according to the file extension.\n"
442 "Raw images can also be output by using '%%d' in the filename\n"
449 /* allocate the output media context */
450 avformat_alloc_output_context2(&oc, NULL, NULL, filename);
452 printf("Could not deduce output format from file extension: using MPEG.\n");
453 avformat_alloc_output_context2(&oc, NULL, "mpeg", filename);
460 /* add the audio and video streams using the default format codecs
461 and initialize the codecs */
464 if (fmt->video_codec != CODEC_ID_NONE) {
465 video_st = add_video_stream(oc, fmt->video_codec);
467 if (fmt->audio_codec != CODEC_ID_NONE) {
468 audio_st = add_audio_stream(oc, fmt->audio_codec);
471 av_dump_format(oc, 0, filename, 1);
473 /* now that all the parameters are set, we can open the audio and
474 video codecs and allocate the necessary encode buffers */
476 open_video(oc, video_st);
478 open_audio(oc, audio_st);
480 /* open the output file, if needed */
481 if (!(fmt->flags & AVFMT_NOFILE)) {
482 if (avio_open(&oc->pb, filename, AVIO_FLAG_WRITE) < 0) {
483 fprintf(stderr, "Could not open '%s'\n", filename);
488 /* write the stream header, if any */
492 /* compute current audio and video time */
494 audio_pts = (double)audio_st->pts.val * audio_st->time_base.num / audio_st->time_base.den;
499 video_pts = (double)video_st->pts.val * video_st->time_base.num / video_st->time_base.den;
503 if ((!audio_st || audio_pts >= STREAM_DURATION) &&
504 (!video_st || video_pts >= STREAM_DURATION))
507 /* write interleaved audio and video frames */
508 if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
509 write_audio_frame(oc, audio_st);
511 write_video_frame(oc, video_st);
515 /* write the trailer, if any. the trailer must be written
516 * before you close the CodecContexts open when you wrote the
517 * header; otherwise write_trailer may try to use memory that
518 * was freed on av_codec_close() */
519 av_write_trailer(oc);
521 /* close each codec */
523 close_video(oc, video_st);
525 close_audio(oc, audio_st);
527 /* free the streams */
528 for(i = 0; i < oc->nb_streams; i++) {
529 av_freep(&oc->streams[i]->codec);
530 av_freep(&oc->streams[i]);
533 if (!(fmt->flags & AVFMT_NOFILE)) {
534 /* close the output file */
538 /* free the stream */