[FFmpeg-devel] [PATCH] nuvdemux: timestamps are signed or well wraped and starting before 0.

[Michael Niedermayer]

On Sun, Nov 25, 2012 at 12:48:09PM +0100, Reimar Döffinger wrote:
> On Sun, Nov 25, 2012 at 05:02:30AM +0100, Michael Niedermayer wrote:
> > Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> > ---
> >  libavformat/nuv.c            |    4 +-
> >  tests/ref/fate/nuv-rtjpeg-fh |  100 +++++++++++++++++++++---------------------
> >  2 files changed, 52 insertions(+), 52 deletions(-)
> > 
> > diff --git a/libavformat/nuv.c b/libavformat/nuv.c
> > index c67c1fa..2b2f22c 100644
> > --- a/libavformat/nuv.c
> > +++ b/libavformat/nuv.c
> > @@ -229,7 +229,7 @@ static int nuv_packet(AVFormatContext *s, AVPacket *pkt) {
> >  
> >                  pkt->pos = pos;
> >                  pkt->flags |= hdr[2] == 0 ? AV_PKT_FLAG_KEY : 0;
> > -                pkt->pts = AV_RL32(&hdr[4]);
> > +                pkt->pts = (int32_t)AV_RL32(&hdr[4]);
> 
> Maybe I am overly pedantic, but isn't this cast strictly speaking
> undefined? It seems to me we use (e.g. in dsicinav.c) constructs like
> sign_extend(AV_RL16(buf), 16); instead of casts.
> Also a test-case/explanation would be nice, because the FATE reference
> at first sight looks a lot worse, not better and it's fairly non-obvious
> why this cases the timestamps to be offset by 80...

in the fate sample
one stream starts with timestamps a bit below 1<<32 and then wraps
the other stream starts later after the wrap
The fate test discards the odd stream so only the stream that starts
later is shown. (its probably a bad idea to discard that stream)
The difference results from different start_time values.

also see the timestamp wraping patch that results in a similar change
to this fate sample

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Observe your enemies, for they first find out your faults. -- Antisthenes
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