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 static float t, tincr, tincr2;
54 static int16_t *samples;
55 static uint8_t *audio_outbuf;
56 static int audio_outbuf_size;
57 static 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 static AVFrame *picture, *tmp_picture;
194 static uint8_t *video_outbuf;
195 static int frame_count, video_outbuf_size;
197 /* add a video output stream */
198 static AVStream *add_video_stream(AVFormatContext *oc, enum CodecID codec_id)
204 st = avformat_new_stream(oc, NULL);
206 fprintf(stderr, "Could not alloc stream\n");
212 /* find the video encoder */
213 codec = avcodec_find_encoder(codec_id);
215 fprintf(stderr, "codec not found\n");
218 avcodec_get_context_defaults3(c, codec);
220 c->codec_id = codec_id;
222 /* put sample parameters */
223 c->bit_rate = 400000;
224 /* resolution must be a multiple of two */
227 /* time base: this is the fundamental unit of time (in seconds) in terms
228 of which frame timestamps are represented. for fixed-fps content,
229 timebase should be 1/framerate and timestamp increments should be
231 c->time_base.den = STREAM_FRAME_RATE;
232 c->time_base.num = 1;
233 c->gop_size = 12; /* emit one intra frame every twelve frames at most */
234 c->pix_fmt = STREAM_PIX_FMT;
235 if (c->codec_id == CODEC_ID_MPEG2VIDEO) {
236 /* just for testing, we also add B frames */
239 if (c->codec_id == CODEC_ID_MPEG1VIDEO){
240 /* Needed to avoid using macroblocks in which some coeffs overflow.
241 This does not happen with normal video, it just happens here as
242 the motion of the chroma plane does not match the luma plane. */
245 // some formats want stream headers to be separate
246 if (oc->oformat->flags & AVFMT_GLOBALHEADER)
247 c->flags |= CODEC_FLAG_GLOBAL_HEADER;
252 static AVFrame *alloc_picture(enum PixelFormat pix_fmt, int width, int height)
255 uint8_t *picture_buf;
258 picture = avcodec_alloc_frame();
261 size = avpicture_get_size(pix_fmt, width, height);
262 picture_buf = av_malloc(size);
267 avpicture_fill((AVPicture *)picture, picture_buf,
268 pix_fmt, width, height);
272 static void open_video(AVFormatContext *oc, AVStream *st)
279 /* find the video encoder */
280 codec = avcodec_find_encoder(c->codec_id);
282 fprintf(stderr, "codec not found\n");
287 if (avcodec_open(c, codec) < 0) {
288 fprintf(stderr, "could not open codec\n");
293 if (!(oc->oformat->flags & AVFMT_RAWPICTURE)) {
294 /* allocate output buffer */
295 /* XXX: API change will be done */
296 /* buffers passed into lav* can be allocated any way you prefer,
297 as long as they're aligned enough for the architecture, and
298 they're freed appropriately (such as using av_free for buffers
299 allocated with av_malloc) */
300 video_outbuf_size = 200000;
301 video_outbuf = av_malloc(video_outbuf_size);
304 /* allocate the encoded raw picture */
305 picture = alloc_picture(c->pix_fmt, c->width, c->height);
307 fprintf(stderr, "Could not allocate picture\n");
311 /* if the output format is not YUV420P, then a temporary YUV420P
312 picture is needed too. It is then converted to the required
315 if (c->pix_fmt != PIX_FMT_YUV420P) {
316 tmp_picture = alloc_picture(PIX_FMT_YUV420P, c->width, c->height);
318 fprintf(stderr, "Could not allocate temporary picture\n");
324 /* prepare a dummy image */
325 static void fill_yuv_image(AVFrame *pict, int frame_index, int width, int height)
332 for (y = 0; y < height; y++) {
333 for (x = 0; x < width; x++) {
334 pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
339 for (y = 0; y < height/2; y++) {
340 for (x = 0; x < width/2; x++) {
341 pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
342 pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
347 static void write_video_frame(AVFormatContext *oc, AVStream *st)
351 static struct SwsContext *img_convert_ctx;
355 if (frame_count >= STREAM_NB_FRAMES) {
356 /* no more frame to compress. The codec has a latency of a few
357 frames if using B frames, so we get the last frames by
358 passing the same picture again */
360 if (c->pix_fmt != PIX_FMT_YUV420P) {
361 /* as we only generate a YUV420P picture, we must convert it
362 to the codec pixel format if needed */
363 if (img_convert_ctx == NULL) {
364 img_convert_ctx = sws_getContext(c->width, c->height,
368 sws_flags, NULL, NULL, NULL);
369 if (img_convert_ctx == NULL) {
370 fprintf(stderr, "Cannot initialize the conversion context\n");
374 fill_yuv_image(tmp_picture, frame_count, c->width, c->height);
375 sws_scale(img_convert_ctx, tmp_picture->data, tmp_picture->linesize,
376 0, c->height, picture->data, picture->linesize);
378 fill_yuv_image(picture, frame_count, c->width, c->height);
383 if (oc->oformat->flags & AVFMT_RAWPICTURE) {
384 /* raw video case. The API will change slightly in the near
387 av_init_packet(&pkt);
389 pkt.flags |= AV_PKT_FLAG_KEY;
390 pkt.stream_index = st->index;
391 pkt.data = (uint8_t *)picture;
392 pkt.size = sizeof(AVPicture);
394 ret = av_interleaved_write_frame(oc, &pkt);
396 /* encode the image */
397 out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture);
398 /* if zero size, it means the image was buffered */
401 av_init_packet(&pkt);
403 if (c->coded_frame->pts != AV_NOPTS_VALUE)
404 pkt.pts= av_rescale_q(c->coded_frame->pts, c->time_base, st->time_base);
405 if(c->coded_frame->key_frame)
406 pkt.flags |= AV_PKT_FLAG_KEY;
407 pkt.stream_index = st->index;
408 pkt.data = video_outbuf;
411 /* write the compressed frame in the media file */
412 ret = av_interleaved_write_frame(oc, &pkt);
418 fprintf(stderr, "Error while writing video frame\n");
424 static void close_video(AVFormatContext *oc, AVStream *st)
426 avcodec_close(st->codec);
427 av_free(picture->data[0]);
430 av_free(tmp_picture->data[0]);
431 av_free(tmp_picture);
433 av_free(video_outbuf);
436 /**************************************************************/
437 /* media file output */
439 int main(int argc, char **argv)
441 const char *filename;
444 AVStream *audio_st, *video_st;
445 double audio_pts, video_pts;
448 /* initialize libavcodec, and register all codecs and formats */
452 printf("usage: %s output_file\n"
453 "API example program to output a media file with libavformat.\n"
454 "The output format is automatically guessed according to the file extension.\n"
455 "Raw images can also be output by using '%%d' in the filename\n"
462 /* allocate the output media context */
463 avformat_alloc_output_context2(&oc, NULL, NULL, filename);
465 printf("Could not deduce output format from file extension: using MPEG.\n");
466 avformat_alloc_output_context2(&oc, NULL, "mpeg", filename);
473 /* add the audio and video streams using the default format codecs
474 and initialize the codecs */
477 if (fmt->video_codec != CODEC_ID_NONE) {
478 video_st = add_video_stream(oc, fmt->video_codec);
480 if (fmt->audio_codec != CODEC_ID_NONE) {
481 audio_st = add_audio_stream(oc, fmt->audio_codec);
484 av_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 (avio_open(&oc->pb, filename, AVIO_FLAG_WRITE) < 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);
529 /* write the trailer, if any. the trailer must be written
530 * before you close the CodecContexts open when you wrote the
531 * header; otherwise write_trailer may try to use memory that
532 * was freed on av_codec_close() */
533 av_write_trailer(oc);
535 /* close each codec */
537 close_video(oc, video_st);
539 close_audio(oc, audio_st);
541 /* free the streams */
542 for(i = 0; i < oc->nb_streams; i++) {
543 av_freep(&oc->streams[i]->codec);
544 av_freep(&oc->streams[i]);
547 if (!(fmt->flags & AVFMT_NOFILE)) {
548 /* close the output file */
552 /* free the stream */