Sending DV to camcorder over firewire gives dropouts

[Arne Wörner]

Hi!

--- Dieter <freebsd at sopwith.solgatos.com> wrote:
> AMD64 running FreeBSD 6.0 beta3.
> Canon DV NTSC camcorder connected via firewire.
> 
> Playing a tape and recording it on the computer via
> 
> 	fwcontrol -R filename.dv
> 
> appears to work fine.
>
Sweet...
(I am just watching "Dude! Where is my car?) :-))

> Sending the video back to the camcorder via
> 
> 	fwcontrol -S filename.dv
> 
> mostly works, but every 1.5-2 seconds or so I get a momentary
> dropout of both video and audio.  I get the same dropouts
> with a dv file created by "fwcontrol -R" and with dv files
> created
> by ffmpeg.
> 
> This is with the camcorder in "VCR" mode, and stopped (not
> recording).
> The computer is otherwise idle.
> 
> The dropouts are very regular and repeatable, so it probably
> isn't due to
> an occasional transmission error, or the computer being busy for
> a moment.
> 
> 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?
Maybe you could do some experiments:
1. -r 40
2. -r 25
3. -r 20
4. -r 30
and watch for the length of drop outs and inter-mittance-time (is
that the right word? I mean: The time between drop outs)...

-Arne


	
		
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