On Thu, 16. May 00:43, Michael Niedermayer wrote:
> 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.
ok, thanks. I'll look over this.
Andriy
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