+static double compute_frame_delay(double frame_current_pts, VideoState *is)
+{
+ double actual_delay, delay, sync_threshold, ref_clock, diff;
+
+ /* compute nominal delay */
+ delay = frame_current_pts - is->frame_last_pts;
+ if (delay <= 0 || delay >= 10.0) {
+ /* if incorrect delay, use previous one */
+ delay = is->frame_last_delay;
+ } else {
+ is->frame_last_delay = delay;
+ }
+ is->frame_last_pts = frame_current_pts;
+
+ /* update delay to follow master synchronisation source */
+ if (((is->av_sync_type == AV_SYNC_AUDIO_MASTER && is->audio_st) ||
+ is->av_sync_type == AV_SYNC_EXTERNAL_CLOCK)) {
+ /* if video is slave, we try to correct big delays by
+ duplicating or deleting a frame */
+ ref_clock = get_master_clock(is);
+ diff = frame_current_pts - ref_clock;
+
+ /* skip or repeat frame. We take into account the
+ delay to compute the threshold. I still don't know
+ if it is the best guess */
+ sync_threshold = FFMAX(AV_SYNC_THRESHOLD, delay);
+ if (fabs(diff) < AV_NOSYNC_THRESHOLD) {
+ if (diff <= -sync_threshold)
+ delay = 0;
+ else if (diff >= sync_threshold)
+ delay = 2 * delay;
+ }
+ }
+
+ is->frame_timer += delay;
+ /* compute the REAL delay (we need to do that to avoid
+ long term errors */
+ actual_delay = is->frame_timer - (av_gettime() / 1000000.0);
+ if (actual_delay < 0.010) {
+ /* XXX: should skip picture */
+ actual_delay = 0.010;
+ }
+
+#if defined(DEBUG_SYNC)
+ printf("video: delay=%0.3f actual_delay=%0.3f pts=%0.3f A-V=%f\n",
+ delay, actual_delay, frame_current_pts, -diff);
+#endif
+
+ return actual_delay;
+}
+