[FFmpeg-devel] [PATCH] avformat/rtpdec: Fix prft wallclock time.

[Carl Eugen Hoyos]

Am Di., 30. März 2021 um 17:02 Uhr schrieb James Almer <jamrial at gmail.com>:
>
> On 3/25/2021 1:46 AM, Alok Priyadarshi wrote:
> > Timestamp difference is available in media timebase (1/90K) where as
> > rtcp time is in the default microseconds timebase. This patch fixes
> > the calculated prft wallclock time by rescaling the timestamp delta
> > to the microseconds timebase.
> > ---
> >   libavformat/rtpdec.c | 9 +++++++--
> >   1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/libavformat/rtpdec.c b/libavformat/rtpdec.c
> > index b935dba1b8..21c1d01785 100644
> > --- a/libavformat/rtpdec.c
> > +++ b/libavformat/rtpdec.c
> > @@ -585,14 +585,19 @@ void ff_rtp_parse_set_crypto(RTPDemuxContext *s, const char *suite,
> >   }
> >
> >   static int rtp_set_prft(RTPDemuxContext *s, AVPacket *pkt, uint32_t timestamp) {
> > +    int64_t rtcp_time, delta_timestamp, delta_time;
> > +
> >       AVProducerReferenceTime *prft =
> >           (AVProducerReferenceTime *) av_packet_new_side_data(
> >               pkt, AV_PKT_DATA_PRFT, sizeof(AVProducerReferenceTime));
> >       if (!prft)
> >           return AVERROR(ENOMEM);
> >
> > -    prft->wallclock = ff_parse_ntp_time(s->last_rtcp_ntp_time) - NTP_OFFSET_US +
> > -                      timestamp - s->last_rtcp_timestamp;
> > +    rtcp_time = ff_parse_ntp_time(s->last_rtcp_ntp_time) - NTP_OFFSET_US;
> > +    delta_timestamp = (int64_t)timestamp - (int64_t)s->last_rtcp_timestamp;
> > +    delta_time = av_rescale_q(delta_timestamp, s->st->time_base, AV_TIME_BASE_Q);
> > +
> > +    prft->wallclock = rtcp_time + delta_time;
> >       prft->flags = 24;
> >       return 0;
> >   }
>
> Applied, thanks.

I still believe that such patches should not get applied.

Carl Eugen