[FFmpeg-devel] [PATCH] Extracting NTP timestamp from RTCP

[Michael Niedermayer]

On Sat, Nov 09, 2013 at 11:45:58AM +0100, Michael Niedermayer wrote:
> On Fri, Nov 08, 2013 at 02:14:38PM -0700, Fred Rothganger wrote:
> > On 11/08/2013 01:21 AM, Michael Niedermayer wrote:
> > >why is first_rtcp_ntp_time split in low and high 32bit halfs ?
> > 
> > It was split in my original code for proper conditioning.
> 
> >  doc/APIchanges         |    3 +++
> >  libavformat/avformat.h |    2 +-
> >  libavformat/rtsp.c     |    9 +++++++++
> >  libavformat/version.h  |    2 +-
> >  4 files changed, 14 insertions(+), 2 deletions(-)
> > e6e26ffdc263452fadf3f2c6e6ffa038e6ac7ecb  rtsp.patch
> > diff --git a/doc/APIchanges b/doc/APIchanges
> > index dfdc159..be3d90a 100644
> > --- a/doc/APIchanges
> > +++ b/doc/APIchanges
> > @@ -15,6 +15,9 @@ libavutil:     2012-10-22
> >  
> >  API changes, most recent first:
> >  
> > +2013-11-07 - xxxxxxx - lavf 55.21.101 - avformat.h
> > +  Set AVFormatContext.start_time_realtime when decoding.
> > +
> >  2013-11-xx - xxxxxxx - lavc 55.41.100 / 55.25.0 - avcodec.h
> >                         lavu 52.51.100 - frame.h
> >    Add ITU-R BT.2020 and other not yet included values to color primaries,
> > diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> > index 6bd54ce..1c4929d 100644
> > --- a/libavformat/avformat.h
> > +++ b/libavformat/avformat.h
> > @@ -1127,7 +1127,7 @@ typedef struct AVFormatContext {
> >       * since the unix epoch (00:00 1st January 1970). That is, pts=0
> >       * in the stream was captured at this real world time.
> >       * - encoding: Set by user.
> > -     * - decoding: Unused.
> > +     * - decoding: Set by libavformt.
> >       */
> >      int64_t start_time_realtime;
> >  
> > diff --git a/libavformat/rtsp.c b/libavformat/rtsp.c
> > index 3b88fc7..c9f4784 100644
> > --- a/libavformat/rtsp.c
> > +++ b/libavformat/rtsp.c
> > @@ -2051,6 +2051,15 @@ redo:
> >                   * as this one. */
> >                  int i;
> >                  AVStream *st = NULL;
> > +                if (s->start_time_realtime == 0) {
> > +                    s->start_time_realtime = av_rescale (rtpctx->first_rtcp_ntp_time - (NTP_OFFSET << 32), 1000000, 1LL << 32);
> > +                    if (rtpctx->st) {
> > +                        s->start_time_realtime -=
> > +                            av_rescale (rtpctx->rtcp_ts_offset,
> > +                                        (uint64_t) rtpctx->st->time_base.num * 1000000,
> > +                                                   rtpctx->st->time_base.den);
> > +                    }
> > +                }
> 
> theres a comment in the code above the added code that seems to
> belong to the code below
> 
> also, how do i test this ? it seems the field is just 0 when reading
> a random rtsp stream

also if 0 means "Not set" then this should be documented

[...]



-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Dictatorship naturally arises out of democracy, and the most aggravated
form of tyranny and slavery out of the most extreme liberty. -- Plato
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