init pes dts and pts to AV_NOPTS_VALUE, fix issue #1297

Originally committed as revision 19546 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mpegts.c

@@ -1061,6 +1061,8 @@ static PESContext *add_pes_stream(MpegTSContext *ts, int pid, int pcr_pid, int s
     pes->pcr_pid = pcr_pid;
     pes->stream_type = stream_type;
     pes->state = MPEGTS_SKIP;
+    pes->pts = AV_NOPTS_VALUE;
+    pes->dts = AV_NOPTS_VALUE;
     tss = mpegts_open_pes_filter(ts, pid, mpegts_push_data, pes);
     if (!tss) {
         av_free(pes);