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example using video encoder latency

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Originally committed as revision 2257 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Fabrice Bellard
2003-09-10 23:09:30 +00:00
parent fa0f62c37d
commit cb0c448a8d
1 changed files with 39 additions and 20 deletions
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33
output_example.c
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@ -34,7 +34,8 @@
/* 5 seconds stream duration */ /* 5 seconds stream duration */
#define STREAM_DURATION 5.0 #define STREAM_DURATION 5.0
#define STREAM_FRAME_RATE 25 /* 25 images/s */
#define STREAM_NB_FRAMES ((int)(STREAM_DURATION * STREAM_FRAME_RATE))
/**************************************************************/ /**************************************************************/
/* audio output */ /* audio output */
@ -192,10 +193,14 @@ AVStream *add_video_stream(AVFormatContext *oc, int codec_id)
c->width = 352; c->width = 352;
c->height = 288; c->height = 288;
/* frames per second */ /* frames per second */
c->frame_rate = 25; c->frame_rate = STREAM_FRAME_RATE;
c->frame_rate_base = 1; c->frame_rate_base = 1;
c->gop_size = 12; /* emit one intra frame every twelve frames */ c->gop_size = 12; /* emit one intra frame every twelve frames at most */
if (c->codec_id == CODEC_ID_MPEG1VIDEO ||
c->codec_id == CODEC_ID_MPEG2VIDEO) {
/* just for testing, we also add B frames */
c->max_b_frames = 2;
}
return st; return st;
} }
@ -294,9 +299,16 @@ void write_video_frame(AVFormatContext *oc, AVStream *st)
{ {
int out_size, ret; int out_size, ret;
AVCodecContext *c; AVCodecContext *c;
AVFrame *picture_ptr;
c = &st->codec; c = &st->codec;
if (frame_count >= STREAM_NB_FRAMES) {
/* no more frame to compress. The codec has a latency of a few
frames if using B frames, so we get the last frames by
passing a NULL picture */
picture_ptr = NULL;
} else {
if (c->pix_fmt != PIX_FMT_YUV420P) { if (c->pix_fmt != PIX_FMT_YUV420P) {
/* as we only generate a YUV420P picture, we must convert it /* as we only generate a YUV420P picture, we must convert it
to the codec pixel format if needed */ to the codec pixel format if needed */
@ -307,19 +319,26 @@ void write_video_frame(AVFormatContext *oc, AVStream *st)
} else { } else {
fill_yuv_image(picture, frame_count, c->width, c->height); fill_yuv_image(picture, frame_count, c->width, c->height);
} }
picture_ptr = picture;
}
if (oc->oformat->flags & AVFMT_RAWPICTURE) { if (oc->oformat->flags & AVFMT_RAWPICTURE) {
/* raw video case. The API will change slightly in the near /* raw video case. The API will change slightly in the near
futur for that */ futur for that */
ret = av_write_frame(oc, st->index, ret = av_write_frame(oc, st->index,
(uint8_t *)picture, sizeof(AVPicture)); (uint8_t *)picture_ptr, sizeof(AVPicture));
} else { } else {
/* encode the image */ /* encode the image */
out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture); out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture_ptr);
/* if zero size, it means the image was buffered */
if (out_size != 0) {
/* write the compressed frame in the media file */ /* write the compressed frame in the media file */
/* XXX: in case of B frames, the pts is not yet valid */
ret = av_write_frame(oc, st->index, video_outbuf, out_size); ret = av_write_frame(oc, st->index, video_outbuf, out_size);
} else {
ret = 0;
}
} }
if (ret != 0) { if (ret != 0) {
fprintf(stderr, "Error while writing video frame\n"); fprintf(stderr, "Error while writing video frame\n");