avsync patch by (Gildas Bazin <gbazin at altern dot org>)

Originally committed as revision 2805 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mpegts.c

@@ -836,6 +836,7 @@ static void mpegts_push_data(void *opaque,
                     memcpy(pkt->data, p, len);
                     pkt->stream_index = pes->st->index;
                     pkt->pts = pes->pts;
+                    pkt->dts = pes->dts;
                     /* reset pts values */
                     pes->pts = AV_NOPTS_VALUE;
                     pes->dts = AV_NOPTS_VALUE;

libavformat/utils.c

@@ -625,8 +625,14 @@ static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
     } else {
         /* presentation is not delayed : PTS and DTS are the same */
         if (pkt->pts == AV_NOPTS_VALUE) {
-            pkt->pts = st->cur_dts;
-            pkt->dts = st->cur_dts;
+            if (pkt->dts == AV_NOPTS_VALUE) {
+                pkt->pts = st->cur_dts;
+                pkt->dts = st->cur_dts;
+            }
+            else {
+                st->cur_dts = pkt->dts;
+                pkt->pts = pkt->dts;
+            }
         } else {
             st->cur_dts = pkt->pts;
             pkt->dts = pkt->pts;