[FFmpeg-devel] [PATCH] fbdev: simplify logic in fbdev_read_packet()

[Michael Niedermayer]

On Mon, Apr 11, 2011 at 10:56:45AM +0200, Stefano Sabatini wrote:
> On date Monday 2011-04-11 03:02:33 +0200, Michael Niedermayer encoded:
> > Hi
> > 
> > ive seen this in libav (and skiped it because its obviosuly
> > buggy) but seem to have missed it here :(
> > sorry, for the (too) late review
> > 
> > On Sat, Mar 12, 2011 at 03:28:40PM +0100, Stefano Sabatini wrote:
> > > ---
> > >  libavdevice/fbdev.c |   18 ++++++++----------
> > >  1 files changed, 8 insertions(+), 10 deletions(-)
> > > 
> > > diff --git a/libavdevice/fbdev.c b/libavdevice/fbdev.c
> > > index 121f02c..37bba3d 100644
> > > --- a/libavdevice/fbdev.c
> > > +++ b/libavdevice/fbdev.c
> > > @@ -190,22 +190,20 @@ static int fbdev_read_packet(AVFormatContext *avctx, AVPacket *pkt)
> > >          fbdev->time_frame = av_gettime();
> > >  
> > >      /* wait based on the frame rate */
> > > -    while (1) {
> > > -        curtime = av_gettime();
> > > -        delay = fbdev->time_frame - curtime;
> > > -        av_dlog(avctx,
> > > -                "time_frame:%"PRId64" curtime:%"PRId64" delay:%"PRId64"\n",
> > > -                fbdev->time_frame, curtime, delay);
> > > -        if (delay <= 0) {
> > > -            fbdev->time_frame += INT64_C(1000000) * av_q2d(fbdev->time_base);
> > > -            break;
> > > -        }
> > > +    curtime = av_gettime();  <-------------------------- time read
> > > +    delay = fbdev->time_frame - curtime;
> > > +    av_dlog(avctx,
> > > +            "time_frame:%"PRId64" curtime:%"PRId64" delay:%"PRId64"\n",
> > > +            fbdev->time_frame, curtime, delay);
> > > +    if (delay > 0) {
> > >          if (avctx->flags & AVFMT_FLAG_NONBLOCK)
> > >              return AVERROR(EAGAIN);
> > >          ts.tv_sec  =  delay / 1000000;
> > >          ts.tv_nsec = (delay % 1000000) * 1000;
> > >          while (nanosleep(&ts, &ts) < 0 && errno == EINTR); <--------------------wait
> > >      }
> > > +    /* compute the time of the next frame */
> > > +    fbdev->time_frame += INT64_C(1000000) * av_q2d(fbdev->time_base);
> > >  
> > >      if ((ret = av_new_packet(pkt, fbdev->frame_size)) < 0)
> > >          return ret;
> > 
> > some point later <-------------------- read frame
> > even later   <------------------- curtime from above used, but its no
> >                                   longer correct due to the wait
> 
> Ah I see it now, I suppose we could put a curtime = av_gettime() after
> the nanosleep call, or simply leave the code as it is now.

change it whichever way you prefer

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

He who knows, does not speak. He who speaks, does not know. -- Lao Tsu
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