On Fri, Dec 29, 2017 at 8:00 PM, Nicolas George <geo...@nsup.org> wrote:
> Hi. Sorry for having missed your reply earlier. > > 吴志强 (2017-12-18): > > I see wrap timestamp control is enable by pts_wrap_bits(default 33), > > but mp4 demuxer will later set this to 64 (means disabled). > > Now pts_wrap_bits are always tied to 33 without copy it, which seems > > strange. > > I understand the logic of this patch less and less. Why are you speaking > about the MP4 demuxer? > > If I understand correctly how unwrapping timestamp works, concat should > never have to do it. > > > 2017-12-17 22:55 GMT+08:00 Nicolas George <geo...@nsup.org>: > > Please remember that top-posting on this list is forbidden. If you do > not know what it means, look it up. > > Regards, > > -- > Nicolas George > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > Sorry for top-posting. Normally pts_wrap_reference is based on the first packet when calling ff_read_packet, which will call function update_wrap_reference , in libavformat/utils line 734: if (ref == AV_NOPTS_VALUE) ref = pkt->pts; if (st->pts_wrap_reference != AV_NOPTS_VALUE || st->pts_wrap_bits >= 63 || ref == AV_NOPTS_VALUE || !s->correct_ts_overflow) return 0; ref &= (1LL << st->pts_wrap_bits)-1; // reference time stamp should be 60 s before first time stamp pts_wrap_reference = ref - av_rescale(60, st->time_base.den, st->time_base.num); Because concat_read_header and concat_seek do not call ff_read_packet and open_file does not copy pts_wrap_reference, it is constant value during playing. If demuxing packets like avformat_open_input => avformat_seek_file => av_read_frame and seek time is larger than 60s, the constant reference time will be positive value and not indicate the normal wrap margin. Then seeking to time before pts_wrap_reference may generate huge timestamp, which not expected. Thanks. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
