@@ -95,6 +95,8 @@ typedef struct MatroskaMuxContext {

     AVPacket        cur_audio_pkt;

     int have_attachments;

+

+    int64_t ts_offset;

 } MatroskaMuxContext;

@@ -1265,9 +1267,18 @@ static int mkv_write_packet(AVFormatContext *s, AVPacket *pkt)

     AVIOContext *pb = s->pb->seekable ? s->pb : mkv->dyn_bc;

     AVCodecContext *codec = s->streams[pkt->stream_index]->codec;

     int ret, keyframe = !!(pkt->flags & AV_PKT_FLAG_KEY);

-    int64_t ts = mkv->tracks[pkt->stream_index].write_dts ? pkt->dts : pkt->pts;

+    int64_t ts;

     int cluster_size = avio_tell(pb) - (s->pb->seekable ? mkv->cluster_pos : 0);

+    if (pkt->dts < 0 && !mkv->ts_offset)

+        mkv->ts_offset = -pkt->dts;

+

+    pkt->dts += mkv->ts_offset;

+    if (pkt->pts != AV_NOPTS_VALUE)

+        pkt->pts += mkv->ts_offset;

+

+    ts = mkv->tracks[pkt->stream_index].write_dts ? pkt->dts : pkt->pts;

+

     // start a new cluster every 5 MB or 5 sec, or 32k / 1 sec for streaming or

     // after 4k and on a keyframe

     if (mkv->cluster_pos != -1 &&