decoder: mpeg2: respect any input PTS provided for a frame.

The timestamp generator in gstvaapidecoder_mpeg2.c always interpolated
frame timestamps within a GOP, even when it's been fed input PTS for
every frame.

That leads to incorrect output timestamps in some situations - for example
live playback where input timestamps have been scaled based on arrival time
from the network and don't exactly match the framerate.

https://bugzilla.gnome.org/show_bug.cgi?id=732719

diff --git a/gst-libs/gst/vaapi/gstvaapidecoder_mpeg2.c b/gst-libs/gst/vaapi/gstvaapidecoder_mpeg2.c
index 3f30f0b..c3ab7a6 100644 (file)
--- a/gst-libs/gst/vaapi/gstvaapidecoder_mpeg2.c
+++ b/gst-libs/gst/vaapi/gstvaapidecoder_mpeg2.c
@@ -130,7 +130,9 @@ pts_eval(PTSGenerator *tsg, GstClockTime pic_pts, guint pic_tsn)
     if (!GST_CLOCK_TIME_IS_VALID(tsg->gop_pts))
         tsg->gop_pts = 0;
 
-    pts = tsg->gop_pts + pts_get_duration(tsg, tsg->ovl_tsn * 1024 + pic_tsn);
+    pts = pic_pts;
+    if (!GST_CLOCK_TIME_IS_VALID (pts))
+       pts = tsg->gop_pts + pts_get_duration(tsg, tsg->ovl_tsn * 1024 + pic_tsn);
 
     if (!GST_CLOCK_TIME_IS_VALID(tsg->max_pts) || tsg->max_pts < pts)
         tsg->max_pts = pts;
@@ -142,6 +144,7 @@ pts_eval(PTSGenerator *tsg, GstClockTime pic_pts, guint pic_tsn)
         tsg->ovl_tsn++;
     }
     tsg->lst_tsn = pic_tsn;
+
     return pts;
 }