ffplay同步的时候可以通过以下代码丢帧,
如果代码中time - is->frame_timer > AV_SYNC_THRESHOLD_MAX 成立,
则会将is_frame_timer设置成time,这样在time > is->frame_timer + duration是不会成立的,就不会丢掉该帧,这种情况是怎么实现同步的呢
/* compute nominal last_duration */
last_duration = vp_duration(is, lastvp, vp);
if (redisplay)
delay = 0.0;
else
delay = compute_target_delay(last_duration, is);
time= av_gettime_relative()/1000000.0;
if (time < is->frame_timer + delay && !redisplay) {
*remaining_time = FFMIN(is->frame_timer + delay - time, *remaining_time);
return;
}
is->frame_timer += delay;
if (delay > 0 && time - is->frame_timer > AV_SYNC_THRESHOLD_MAX)
is->frame_timer = time;
SDL_LockMutex(is->pictq.mutex);
if (!redisplay && !isnan(vp->pts))
update_video_pts(is, vp->pts, vp->pos, vp->serial);
SDL_UnlockMutex(is->pictq.mutex);
if (frame_queue_nb_remaining(&is->pictq) > 1) {
Frame *nextvp = frame_queue_peek_next(&is->pictq);
duration = vp_duration(is, vp, nextvp);
if(!is->step && (redisplay || framedrop>0 || (framedrop && get_master_sync_type(is) != AV_SYNC_VIDEO_MASTER)) && time > is->frame_timer + duration){
if (!redisplay)
is->frame_drops_late++;
frame_queue_next(&is->pictq);
redisplay = 0;
goto retry;
}
}