[mythtv-users] Fuzz in my video output

[Daniel Kristjansson]

On Mon, 2006-06-19 at 16:02 -0600, Brian Wood wrote:
> >> It's probably being transmitted intentionally, it is data, in the
> >> digital equivalent of the vertical blanking interval.
> >> Usually most TVs overscan just a bit to prevent this showing up in
> >> the picture.
> > I'm viewing this on my monitor (Dell 24 inch 2405FPW LCD).. have  
> > you heard of it happening on monitors as well?
> Especially on monitors, because they normally do not overscan at all.
> I think Myth has some overscan settings in it, I'm not by my machine  
> at the moment and so can't check.
> But I want to be sure this is what the problem is, I've never watched  
> QAM channels enough to notice if there is usually a bunch of data at  
> the top.
> Can anybody else confirm this ? The description certainly sounds like  
> what data would look like in that position.

I can confirm this is VBI data. This happens when the broadcaster or
cable operator captures the entire frame of a NTSC stream. If you use
either of the computer inputs on the monitor it won't do any overscan
so you will see this data. MythTV can scale the video up a bit to hide
this data. This one of the playback options and is called "overscan"
in 0.19 and 0.19-fixes.

-- Daniel