[SDL] Multiple Hardware Overlay support

[Stephane Marchesin]

thulasidhar at soc-soft.com wrote:
>
> Hi all,
>
>  
>
> I am planning to buy a graphics card (nvidia quadro fx) that supports 
> multiple hardware overlay planes.
>
> The main use of this card is to overlay some indexed images onto 
> video, during playback (in linux).
>
> The specs of the card say that it supports multiple hardware overlays.
>
> I want to know how to operate on each plane in SDL?
>
> Will SDL give me separate handles to each plane, so that I write into 
> it and they get blended and displayed in the hardware?
>
> If I create 2 surfaces in SDL will they correspond to separate 
> hardware planes?
>
 From what I recall, nvidia quadro FX cards only have a single hardware 
YUV overlay. But these cards emulate 2nd and further overlays using the 
blitter. So, depending on what you do, that should work.

These cards also feature a RGBA overlay, which I think goes unused 99% 
of the time (at least I don't think SDL will make any use of it).

The best I think is to get someone with such a card to run "xvinfo" on 
his machine. It will list the overlays. For example here :
  Adaptor #0: "NV17 Video Texture"
    number of ports: 1
[...]
  Adaptor #1: "NV05 Video Blitter"
    number of ports: 32

Which means I have 1 hardware YUV overlay, and 32 overlays emulated with 
the blitter available.

Stephane