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>
40 /* 5 seconds stream duration */
41 #define STREAM_DURATION 200.0
42 #define STREAM_FRAME_RATE 25 /* 25 images/s */
43 #define STREAM_NB_FRAMES ((int)(STREAM_DURATION * STREAM_FRAME_RATE))
44 #define STREAM_PIX_FMT AV_PIX_FMT_YUV420P /* default pix_fmt */
46 static int sws_flags = SWS_BICUBIC;
48 /**************************************************************/
51 static float t, tincr, tincr2;
52 static int16_t *samples;
53 static int audio_input_frame_size;
55 /* Add an output stream. */
56 static AVStream *add_stream(AVFormatContext *oc, AVCodec **codec,
57 enum AVCodecID codec_id)
62 /* find the encoder */
63 *codec = avcodec_find_encoder(codec_id);
65 fprintf(stderr, "Could not find codec\n");
69 st = avformat_new_stream(oc, *codec);
71 fprintf(stderr, "Could not allocate stream\n");
74 st->id = oc->nb_streams-1;
77 switch ((*codec)->type) {
78 case AVMEDIA_TYPE_AUDIO:
80 c->sample_fmt = AV_SAMPLE_FMT_S16;
82 c->sample_rate = 44100;
86 case AVMEDIA_TYPE_VIDEO:
87 avcodec_get_context_defaults3(c, *codec);
88 c->codec_id = codec_id;
91 /* Resolution must be a multiple of two. */
94 /* timebase: This is the fundamental unit of time (in seconds) in terms
95 * of which frame timestamps are represented. For fixed-fps content,
96 * timebase should be 1/framerate and timestamp increments should be
98 c->time_base.den = STREAM_FRAME_RATE;
100 c->gop_size = 12; /* emit one intra frame every twelve frames at most */
101 c->pix_fmt = STREAM_PIX_FMT;
102 if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
103 /* just for testing, we also add B frames */
106 if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO) {
107 /* Needed to avoid using macroblocks in which some coeffs overflow.
108 * This does not happen with normal video, it just happens here as
109 * the motion of the chroma plane does not match the luma plane. */
118 /* Some formats want stream headers to be separate. */
119 if (oc->oformat->flags & AVFMT_GLOBALHEADER)
120 c->flags |= CODEC_FLAG_GLOBAL_HEADER;
125 /**************************************************************/
128 static float t, tincr, tincr2;
129 static int16_t *samples;
130 static int audio_input_frame_size;
132 static void open_audio(AVFormatContext *oc, AVCodec *codec, AVStream *st)
139 if (avcodec_open2(c, codec, NULL) < 0) {
140 fprintf(stderr, "Could not open audio codec\n");
144 /* init signal generator */
146 tincr = 2 * M_PI * 110.0 / c->sample_rate;
147 /* increment frequency by 110 Hz per second */
148 tincr2 = 2 * M_PI * 110.0 / c->sample_rate / c->sample_rate;
150 if (c->codec->capabilities & CODEC_CAP_VARIABLE_FRAME_SIZE)
151 audio_input_frame_size = 10000;
153 audio_input_frame_size = c->frame_size;
154 samples = av_malloc(audio_input_frame_size *
155 av_get_bytes_per_sample(c->sample_fmt) *
158 fprintf(stderr, "Could not allocate audio samples buffer\n");
163 /* Prepare a 16 bit dummy audio frame of 'frame_size' samples and
164 * 'nb_channels' channels. */
165 static void get_audio_frame(int16_t *samples, int frame_size, int nb_channels)
171 for (j = 0; j < frame_size; j++) {
172 v = (int)(sin(t) * 10000);
173 for (i = 0; i < nb_channels; i++)
180 static void write_audio_frame(AVFormatContext *oc, AVStream *st)
183 AVPacket pkt = { 0 }; // data and size must be 0;
184 AVFrame *frame = avcodec_alloc_frame();
187 av_init_packet(&pkt);
190 get_audio_frame(samples, audio_input_frame_size, c->channels);
191 frame->nb_samples = audio_input_frame_size;
192 avcodec_fill_audio_frame(frame, c->channels, c->sample_fmt,
194 audio_input_frame_size *
195 av_get_bytes_per_sample(c->sample_fmt) *
198 ret = avcodec_encode_audio2(c, &pkt, frame, &got_packet);
200 fprintf(stderr, "Error encoding audio frame\n");
207 pkt.stream_index = st->index;
209 /* Write the compressed frame to the media file. */
210 if (av_interleaved_write_frame(oc, &pkt) != 0) {
211 fprintf(stderr, "Error while writing audio frame\n");
214 avcodec_free_frame(&frame);
217 static void close_audio(AVFormatContext *oc, AVStream *st)
219 avcodec_close(st->codec);
224 /**************************************************************/
227 static AVFrame *frame;
228 static AVPicture src_picture, dst_picture;
229 static int frame_count;
231 static void open_video(AVFormatContext *oc, AVCodec *codec, AVStream *st)
234 AVCodecContext *c = st->codec;
237 if (avcodec_open2(c, codec, NULL) < 0) {
238 fprintf(stderr, "Could not open video codec\n");
242 /* allocate and init a re-usable frame */
243 frame = avcodec_alloc_frame();
245 fprintf(stderr, "Could not allocate video frame\n");
249 /* Allocate the encoded raw picture. */
250 ret = avpicture_alloc(&dst_picture, c->pix_fmt, c->width, c->height);
252 fprintf(stderr, "Could not allocate picture\n");
256 /* If the output format is not YUV420P, then a temporary YUV420P
257 * picture is needed too. It is then converted to the required
259 if (c->pix_fmt != AV_PIX_FMT_YUV420P) {
260 ret = avpicture_alloc(&src_picture, AV_PIX_FMT_YUV420P, c->width, c->height);
262 fprintf(stderr, "Could not allocate temporary picture\n");
267 /* copy data and linesize picture pointers to frame */
268 *((AVPicture *)frame) = dst_picture;
271 /* Prepare a dummy image. */
272 static void fill_yuv_image(AVPicture *pict, int frame_index,
273 int width, int height)
280 for (y = 0; y < height; y++)
281 for (x = 0; x < width; x++)
282 pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
285 for (y = 0; y < height / 2; y++) {
286 for (x = 0; x < width / 2; x++) {
287 pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
288 pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
293 static void write_video_frame(AVFormatContext *oc, AVStream *st)
296 static struct SwsContext *sws_ctx;
297 AVCodecContext *c = st->codec;
299 if (frame_count >= STREAM_NB_FRAMES) {
300 /* No more frames to compress. The codec has a latency of a few
301 * frames if using B-frames, so we get the last frames by
302 * passing the same picture again. */
304 if (c->pix_fmt != AV_PIX_FMT_YUV420P) {
305 /* as we only generate a YUV420P picture, we must convert it
306 * to the codec pixel format if needed */
308 sws_ctx = sws_getContext(c->width, c->height, AV_PIX_FMT_YUV420P,
309 c->width, c->height, c->pix_fmt,
310 sws_flags, NULL, NULL, NULL);
313 "Could not initialize the conversion context\n");
317 fill_yuv_image(&src_picture, frame_count, c->width, c->height);
319 (const uint8_t * const *)src_picture.data, src_picture.linesize,
320 0, c->height, dst_picture.data, dst_picture.linesize);
322 fill_yuv_image(&dst_picture, frame_count, c->width, c->height);
326 if (oc->oformat->flags & AVFMT_RAWPICTURE) {
327 /* Raw video case - directly store the picture in the packet */
329 av_init_packet(&pkt);
331 pkt.flags |= AV_PKT_FLAG_KEY;
332 pkt.stream_index = st->index;
333 pkt.data = dst_picture.data[0];
334 pkt.size = sizeof(AVPicture);
336 ret = av_interleaved_write_frame(oc, &pkt);
338 /* encode the image */
342 av_init_packet(&pkt);
343 pkt.data = NULL; // packet data will be allocated by the encoder
346 ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
348 fprintf(stderr, "Error encoding video frame\n");
352 /* If size is zero, it means the image was buffered. */
354 if (c->coded_frame->key_frame)
355 pkt.flags |= AV_PKT_FLAG_KEY;
357 pkt.stream_index = st->index;
359 /* Write the compressed frame to the media file. */
360 ret = av_interleaved_write_frame(oc, &pkt);
366 fprintf(stderr, "Error while writing video frame\n");
372 static void close_video(AVFormatContext *oc, AVStream *st)
374 avcodec_close(st->codec);
375 av_free(src_picture.data[0]);
376 av_free(dst_picture.data[0]);
380 /**************************************************************/
381 /* media file output */
383 int main(int argc, char **argv)
385 const char *filename;
388 AVStream *audio_st, *video_st;
389 AVCodec *audio_codec, *video_codec;
390 double audio_pts, video_pts;
393 /* Initialize libavcodec, and register all codecs and formats. */
397 printf("usage: %s output_file\n"
398 "API example program to output a media file with libavformat.\n"
399 "This program generates a synthetic audio and video stream, encodes and\n"
400 "muxes them into a file named output_file.\n"
401 "The output format is automatically guessed according to the file extension.\n"
402 "Raw images can also be output by using '%%d' in the filename.\n"
409 /* allocate the output media context */
410 avformat_alloc_output_context2(&oc, NULL, NULL, filename);
412 printf("Could not deduce output format from file extension: using MPEG.\n");
413 avformat_alloc_output_context2(&oc, NULL, "mpeg", filename);
420 /* Add the audio and video streams using the default format codecs
421 * and initialize the codecs. */
425 if (fmt->video_codec != AV_CODEC_ID_NONE) {
426 video_st = add_stream(oc, &video_codec, fmt->video_codec);
428 if (fmt->audio_codec != AV_CODEC_ID_NONE) {
429 audio_st = add_stream(oc, &audio_codec, fmt->audio_codec);
432 /* Now that all the parameters are set, we can open the audio and
433 * video codecs and allocate the necessary encode buffers. */
435 open_video(oc, video_codec, video_st);
437 open_audio(oc, audio_codec, audio_st);
439 av_dump_format(oc, 0, filename, 1);
441 /* open the output file, if needed */
442 if (!(fmt->flags & AVFMT_NOFILE)) {
443 if (avio_open(&oc->pb, filename, AVIO_FLAG_WRITE) < 0) {
444 fprintf(stderr, "Could not open '%s'\n", filename);
449 /* Write the stream header, if any. */
450 if (avformat_write_header(oc, NULL) < 0) {
451 fprintf(stderr, "Error occurred when opening output file\n");
458 /* Compute current audio and video time. */
460 audio_pts = (double)audio_st->pts.val * audio_st->time_base.num / audio_st->time_base.den;
465 video_pts = (double)video_st->pts.val * video_st->time_base.num /
466 video_st->time_base.den;
470 if ((!audio_st || audio_pts >= STREAM_DURATION) &&
471 (!video_st || video_pts >= STREAM_DURATION))
474 /* write interleaved audio and video frames */
475 if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
476 write_audio_frame(oc, audio_st);
478 write_video_frame(oc, video_st);
479 frame->pts += av_rescale_q(1, video_st->codec->time_base, video_st->time_base);
483 /* Write the trailer, if any. The trailer must be written before you
484 * close the CodecContexts open when you wrote the header; otherwise
485 * av_write_trailer() may try to use memory that was freed on
486 * av_codec_close(). */
487 av_write_trailer(oc);
489 /* Close each codec. */
491 close_video(oc, video_st);
493 close_audio(oc, audio_st);
495 /* Free the streams. */
496 for (i = 0; i < oc->nb_streams; i++) {
497 av_freep(&oc->streams[i]->codec);
498 av_freep(&oc->streams[i]);
501 if (!(fmt->flags & AVFMT_NOFILE))
502 /* Close the output file. */
505 /* free the stream */