[mythtv] 4:3 content on 16:9 HDTV & Black bars - revisited

Doug Larrick dougl at charter.net
Tue Sep 14 19:52:47 EDT 2004

Buechler, Mark R wrote:
> I asked a question a few months ago about watching 4:3 content on a 16:9
> screen with the black vertical bars. I didn't get much of a response and I
> really haven't thought of it much until recently when I looked at a movie
> which had some bright (almost white) scenes and I noticed, very clearly, the
> effects of the black bars. The 4:3 area of the screen looks noticeably more
> yellow than the black-barred portions. I looked at the code and it seems the
> black bars are generated from an X definition of black (possibly coming from
> xcolormap?). I'm not real familiar with X calls.
> I'd like to slow down the effect of the black bars by adjusting the black to
> a dark gray. Before I look further into it, has anyone already done so? Is
> there a patch already out there? I'm quite concerned after seeing the
> effects on a TV which is only a year old and doesn't get much use during the
> day.

One thought is that the newest nVidia driver claims to have the 
capability of rendering video (Xv? XvMC? I don't recall) onto an OpenGL 
surface.  If you then remapped that surface nonlinearly onto the screen, 
you'd get a nonuniform stretch.

As far as making the bars grey instead of black, look at DrawUnusedRects 
in the video out class that you use.

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