// duration, but only helps for this particular track, not
// for the other ones that are flushed at the same time.
trk->track_duration = pkt->dts - trk->start_dts;
// duration, but only helps for this particular track, not
// for the other ones that are flushed at the same time.
trk->track_duration = pkt->dts - trk->start_dts;