[vlc] Re: video wall question

[Andreas Schiffler]

Sure, you normally want to display full screen, but you might need black 
bars at different positions. Imagine a video wall implementation with 4x 
16:9 screens. To display a 4:3 video one needs to place the pieces at 
the left (or right) edge of the screen and fill the rest with black (or 
don't draw at all).

The selection of piece to monitor is typically done by the graphics 
driver setup (monitor 1 left of monitor 2, etc.) which in essence 
provides a virtual screen area. In fact I couldn't figure what the the 
"wall" filter was really doing. When I tried the "wall" option on a 
640x480 video a 2x2 setupactivating part 1 and 2 and found them to 
appear in the upper left and lower right corners of my 1024x768 screen - 
quite a counterintuitive positioning. One should at least add the 
possibility to use absolute subwindow positioning for the "wall" filter.

The more general approach would be to map source rectangles to target 
rectangles - and optimize to the full-screen case as a default setting.

I'm also not sure if YUV scaling is active on Linux (or Windows for for 
that matter) for more complex multi monitor setups (like one AGP and one 
PCI Nvidia cards for a 2x2 setup and 4 monitors, or 3 PCI Matrox MMS 
cards for a 3x3 setup and 9 monitors). Anyone has any experience with that?

Cheers
Andreas


Sigmund Augdal wrote:

>I see no reason for a window not to be fullscreen in this setip. The scaling
>to fullscreen is already implemented in vlc. What whould be a cool feature
>was for the wall filter to automatically tell each window it creates which
>monitor it should use.
>
>Sigmund
>
>  
>
>>OK, so it should be fairly easy to extend the wall filter to allow the
>>following adjustments:
>> (A) optionally sub-select a rectangle from the source part
>> (B) scale this rectangle to the original destination size
>>to account for monitor frames in a video-wall matrix.
>>
>>I'll try to make a version of the existing wall filter to implement this
>>if I can figure out the source and pixel format.
>>
>>Bye
>>Andreas
>>
>>
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