[mythtv-users] Big fat blue bar with Internal player

James Oltman cnlibmyth at gmail.com
Thu Jun 23 14:51:47 UTC 2005

So does everyone think I am crazy?  

> > I think this is a problem with the nvidia driver.  The default color
> > for the video overlay is blue so it outputs blue for resolutions that
> > do not take up the whole screen.  You have to use the xvattr command
> > to set the overlay color to black:
> >
> > xvattr -a XV_COLORKEY -v 0
> >
> > You may have to install xvattr.
> I'm not sure I'd call it a problem with the NVIDIA driver.  Usually,
> when a driver causes hardware to do exactly what the software requests,
> that's not considered a problem.  ;)
> Xv--the X Windows Video Extension--is built around the idea that a video
> area is defined by using a specific color, the color key.  Any pixels on
> screen that were painted that color are replaced with the appropriate
> colors for the video being played.  This allows Xv to use the hardware
> to do a "color replacement" (think green-screens as used in movie
> making) which is much faster than having to determine the appropriate
> boundaries for the video using valid/invalid flags, clipping, etc.
> So, why is the default color key an unusal and very unappealing
> blue-green color that's never used anywhere?  Well, exactly /because/
> it's an unusual, unappealing color that's never used anywhere.  If you
> set the color key to 0 (black) as shown above and put an xterm terminal
> window with black foreground on top of the video while it's playing, you
> might notice the video appearing in the black "behind the words" (or at
> least within the cursor and scrollbars--antialiased text may prevent it
> from showing through the words).  Or, start a terminal with "xterm -bg
> black -fg white" and you can hack your Myth code right on top of TV (a
> true "lightweight" transparent window--all handled in hardware unlike
> aterm/eterm/etc.).  By using a color that's not ever used, this
> "accidental" replacement never occurs.  The valid range of values for
> the colorkey is 0 through 2147483615, so my recommendation is to pick
> something close to--but not equal to--0, such as 10 or 30 or even 1 (all
> of which are only likely to be used for the occasional pixel in
> antialiased text).
> Since MythTV is likely to be used such that there are never windows on
> top of the video, using a color key of 0 is not a problem, but on your
> desktop it's likely to cause some unusal (disconcerting?/strangely
> appealing?) effects you might not expect.  And, since human eyes can't
> distinguish between 0 and 10, you might as well choose something
> appropriate that won't be a problem anywhere.
> Just wanted to ensure blame doesn't go misplaced.  I'll admit NVIDIA has
> some work to do on their drivers--but not here.  :)
> Mike
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