On Tue, May 14, 2019 at 05:54:21PM -0400, Andriy Gelman wrote: > From: Andriy Gelman <andriy.gel...@gmail.com> > > Fixes Ticket #7895. > > Currently, timestamp interpolation is disabled by default in H264 and > HEVC. This creates playback issues when the demuxer does not output a > valid timestamp. This patch allows interpolation when no b-frames have > been observed during decoding, which fixes playback issues for some > missing timestamp cases. > --- > libavformat/utils.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/libavformat/utils.c b/libavformat/utils.c > index a63d71b0f4..3dd0bf0d66 100644 > --- a/libavformat/utils.c > +++ b/libavformat/utils.c > @@ -1233,7 +1233,9 @@ static void compute_pkt_fields(AVFormatContext *s, > AVStream *st, > int64_t offset; > AVRational duration; > int onein_oneout = st->codecpar->codec_id != AV_CODEC_ID_H264 && > - st->codecpar->codec_id != AV_CODEC_ID_HEVC; > + st->codecpar->codec_id != AV_CODEC_ID_HEVC || > + (!st->internal->avctx->max_b_frames && > + st->cur_dts != RELATIVE_TS_BASE); /*skip when no > timing info from demuxer */ > > if (s->flags & AVFMT_FLAG_NOFILLIN) > return; > @@ -1272,6 +1274,10 @@ static void compute_pkt_fields(AVFormatContext *s, > AVStream *st, > delay = st->internal->avctx->has_b_frames; > presentation_delayed = 0; > > + /*update max_b_frames if delay is larger */ > + if (delay > st->internal->avctx->max_b_frames) > + st->internal->avctx->max_b_frames = delay; > + > /* XXX: need has_b_frame, but cannot get it if the codec is > * not initialized */ > if (delay && > @@ -1337,7 +1343,8 @@ static void compute_pkt_fields(AVFormatContext *s, > AVStream *st, > presentation_delayed, av_ts2str(pkt->pts), av_ts2str(pkt->dts), > av_ts2str(st->cur_dts), > pkt->stream_index, pc, pkt->duration, delay, onein_oneout); > > - /* Interpolate PTS and DTS if they are not present. We skip H264 > + /* Interpolate PTS and DTS if they are not present. H264/HEVC timestamps > are > + * interpolated only if no b-frames have been observed. Otherwise, we > skip H264/HEVC > * currently because delay and has_b_frames are not reliably set. */ > if ((delay == 0 || (delay == 1 && pc)) && > onein_oneout) {
This may produce some approximate values that are sometimes wrong. If you want to compute exact timestamps, see "Conditional coding of timestamps" in H.222. I only have a older draft here so mine only covers mpeg & h264 but maybe the next covers hevc too. [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB It is dangerous to be right in matters on which the established authorities are wrong. -- Voltaire
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