[FFmpeg-devel] [PATCH] libavformat/utils: Interpolate missing timestamps in H264 and HEVC when no b-frames observed.

[Michael Niedermayer]

On Sat, May 11, 2019 at 11:20:51PM -0400, Andriy Gelman wrote:
> From: Andriy Gelman <andriy.gelman at 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..0668ae3ad1 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);

This needs a comment explaining what it does. Assuming it is what i think it is
then its not completely obvious and could confuse someone working on the code
in the future.


>  
>      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;

do we have a testcase for this ?

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If you fake or manipulate statistics in a paper in physics you will never
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