[MPlayer-dev-eng] Direct3D OSD discussion

[Jim Hauxwell]

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Reimar Döffinger wrote:
> On Mon, Nov 24, 2008 at 11:31:21PM +0000, Jim Hauxwell wrote:
>> 2) uses a L8A8 texture for the osd, so is correctly alphablended.
>> note that even the gl driver has to map the inverted alpha value using
>> software memory copy (line ~551 in vo_gl.c).  It should be possible to
>> come up with a better way to do this.
> 
> I don't think so. Also
> +            if(srca[x]){
> +                dst[x]=(~srca[x] << 8) | src[x];
> +            }
> Why ~srca[x]? I think it should be -srca[x] (a quicker way of writing
> ~srca[x]+1).


No, I wrote what I wrote,

- -srca[i] gives the incorrect answer.  If you take the value 0x0 then
this gets transformed to 0x0 and not 0xFF which is the correct result.
This is a bug in vo_gl.c, not my code.

If you need a small test then I'll knock up the four or so lines to
prove it.

> 
>> Please be aware that although the
>> code may use a glTexSubImage2D() for upload the chances are this is SW
>> in the driver.  It will use less memory bandwidth than the gl version as
>> the gl version has no alpha test to reduce GPU loads from the
>> framebuffer and its a two pass version.
> 
> I never really optimized the OSD-update for speed, never seemed relevant
> even at fullscreen resolution (at least not compared to the font
> rendering).
> But, I can say that back when I tested it, it seemed that NVidia could
> directly use L8 and A8 textures while it looked like L8A8 was converted
> in software before transfer (it caused noticeably higher CPU load).
> That was on an ancient TNT2 though...
> Note that for blending that matches the other vos, one of your blend
> settings should be D3DBLEND_ONE (the one that applies to the OSD
> texture).

Again, this is not a bug in my patch.  The others vos (well gl anyway)
uses a two pass blend, mine is a single pass, so this is the correct
blending.

> 
> Greetings,
> Reimar Döffinger
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> 
> 

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