avformat/segment: re-interleave packets if needed

Fixes part of Ticket 3797
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/segment.c

@@ -766,7 +766,7 @@ static int seg_write_packet(AVFormatContext *s, AVPacket *pkt)
            av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
            av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));
 
-    ret = ff_write_chained(seg->avf, pkt->stream_index, pkt, s, 0);
+    ret = ff_write_chained(seg->avf, pkt->stream_index, pkt, s, seg->initial_offset || seg->reset_timestamps);
 
 fail:
     if (pkt->stream_index == seg->reference_stream_index) {