mplayer: try to handle PTS forward jumps

Raw MPEG streams can contain PTS discontinuities. While the playback
core  has obvious code for handling PTS going backward, PTS going
forward was as far as I can see not handled.

This can be an issue with DVD playback. This wasn't caught earlier,
because DVD playback was just recently switched to demux_lavf, which
implies -no-correct-pts mode. This mode doesn't use PTS in the same way
as the normal playback mode, and as such was too primitive to be
affected by this issue.

Use the following heuristic to handle PTS forward jumps: if the PTS
difference between two frames is higher than 10 seconds, consider it a
reset. (Also, use MSGL_WARN for the PTS discontinuity warnings.)

In this particular case, the MPEG stream was going from pts=304510857
to pts=8589959849 according to ffprobe (raw timestamps), which seems a
bit strange.

Note that this heuristic breaks if the source video has unusually high
frame times. For example Rooster_Teeth_Podcast_191.m4a, an audio file
with a slide show encoded as MJPEG video track.

1 files changed, 6 insertions, 1 deletions

diff --git a/core/mplayer.c b/core/mplayer.c
index 5c4b582be7..f67d10dad4 100644
--- a/core/mplayer.c
+++ b/core/mplayer.c
@@ -2692,7 +2692,7 @@ static double update_video(struct MPContext *mpctx, double endpts)
     if (sh_video->last_pts == MP_NOPTS_VALUE)
         sh_video->last_pts = sh_video->pts;
     else if (sh_video->last_pts > sh_video->pts) {
-        mp_msg(MSGT_CPLAYER, MSGL_INFO, "Decreasing video pts: %f < %f\n",
+        mp_msg(MSGT_CPLAYER, MSGL_WARN, "Decreasing video pts: %f < %f\n",
                sh_video->pts, sh_video->last_pts);
         /* If the difference in pts is small treat it as jitter around the
          * right value (possibly caused by incorrect timestamp ordering) and
@@ -2703,6 +2703,11 @@ static double update_video(struct MPContext *mpctx, double endpts)
             sh_video->last_pts = sh_video->pts;
         else
             sh_video->pts = sh_video->last_pts;
+    } else if (sh_video->pts >= sh_video->last_pts + 60) {
+        // Assume a PTS difference >= 60 seconds is a discontinuity.
+        mp_msg(MSGT_CPLAYER, MSGL_WARN, "Jump in video pts: %f -> %f\n",
+               sh_video->last_pts, sh_video->pts);
+        sh_video->last_pts = sh_video->pts;
     }
     double frame_time = sh_video->pts - sh_video->last_pts;
     sh_video->last_pts = sh_video->pts;