ffmpeg: dont detect slight (0.1sec) backward moving dts as discontinuity

ffmpeg.c

@@ -3043,7 +3043,7 @@ static int process_input(int file_index)
         if(delta < -1LL*dts_delta_threshold*AV_TIME_BASE ||
             (delta > 1LL*dts_delta_threshold*AV_TIME_BASE &&
                 ist->st->codec->codec_type != AVMEDIA_TYPE_SUBTITLE) ||
-            pkt_dts+1<ist->pts){
+            pkt_dts + AV_TIME_BASE/10 < ist->pts){
             ifile->ts_offset -= delta;
             av_log(NULL, AV_LOG_DEBUG,
                    "timestamp discontinuity %"PRId64", new offset= %"PRId64"\n",