Sending DV to camcorder over firewire gives dropouts

[Jacob Meuser]

On Sun, Nov 06, 2005 at 07:09:23PM +0000, Dieter wrote:
> > > Wild Guess Theory #1:
> > > 
> > >     fwcontrol -S reports:
> > > 
> > > 	3948 frames, 131.50 secs, 30.02 frames/sec
> > > 	784 frames, 25.92 secs, 30.24 frames/sec
> > > 	3597 frames, 119.78 secs, 30.03 frames/sec
> > > 
> > >     Shouldn't this be 29.97 fps ?
> > > 
> > I like that theory:
> > 
> > I found in ffmpeg's man page the following option:
> >        -r fps
> >            set frame rate (default = 25)
> > 
> > Dude! Did you use the "-r" option?
> 
> No, didn't need to, ffmpeg figured out to use 29.97 fps
> all by itself, for both input and output.

yes, otherwise it would not be a valid DV file.

> Even if there is something wrong with the output of ffmpeg,
> it would not explain why I get the exact same problem with:
> 
> 	[ push "play" button on camcorder ]
> 	fwcontrol -R filename.dv
> 	[ push "stop" button on camcorder ]
> 	fwcontrol -S filename.dv
> 
> since ffmpeg is not involved in this case.
> 
> It might be that the incorrect fps numbers reported are just
> an artifact of clock resolution and the relatively short times
> involved and packetization/buffering?

seems likely, since the reports with more frames are closer to
the right rate.

-- 
<jakemsr at jakemsr.com>