[vlc] video wall question

[Andreas Schiffler]

I'd like to drive a 3x3 video wall from vlc. 

I know there is a plugin "wall video filter". What does this do? Is
there any documentation?

Ultimately I'd like to implement a new video wall driver that allows for
more control over what is shown where. 

The issue is that for a multi-monitor video display one needs to display
parts of the decoded source image on one of the monitors. Because of the
frame of many displays, adjacent pixels on the monitor are not adjacent
pixels in the source image due to the gap between the monitors.
Therefore a general multi-monitor video wall driver needs to be able map
source rectangles to target rectangles.

Assuming we use a system-managed virtual display, the steps the drivers
has to implement are essentially:
- configure the number of target windows Dn(x,y,w,h
- for each target window configure mappings Sn(x,y,w,h) --> Dn
- open target windows (frameless)
- map source to target (with/without antialiasing)

I have some generic (C) scaling code in my SDL_gfx library (currently
LGPL) that can be GPLed and probably easily modified and used to
implement an unaccelerated rendering step for this driver.  

Any hints and pointers on how I would create such a plugin would be
greatly appreciated. Initially I'd like to implement this on Linux which
is my devel platform.

Best regards
Andreas


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