Re: the basic idea of my codec

Maciek Urbañski wrote:
> 
> ...but computers are getting faster, and there is large enough amount of
> MMX/MMX2/SSE/SSE2/AltiVEC-wizards around to make it faster. And computers
> will be faster and faster, and the standard sohuld stand for a long time.
> ;-)

I have had what I think is an important idea.

What if we could write a player where *all* transforms are performed
on the graphics card?
Some people on this list are working on MC using textured polygons,
but what if also the IDWT could be implemented as "pixel shaders"
that are supported by the latest cards from NVidia, ATI (and soon
also from Permedia and Matrox).

These devices have several limitations of course, such as having
only a single destination pixel at once. The devices are designed
to work with 2D buffers.

I am interested in how your inverse red-black transform would look like.
Is it possible to merge the two inverse transforms into one pass?
Can it be written as a routine with a single destination write?

Despite their shortcomings, GPUs also have certain features for free
that should be exploited if possible:
 - A read from a buffer can linearly interpolate two/four input
   samples at once. (in 1D and 2D respectively)
   This is called texture filtering.
 - GPU:s are often vector-processors, like MMX/SSE/3DNow/Altivec/...
   meaning that we transform all three color channels (Y,Cr,Cb) at once.

If the inverse transform uses a 2D kernel with no holes between
kernel elements (which would be the case if both inverse transforms were
merged into one), then we could use texture filtering to speed it up.
A 2D IDWT would also need less passes on a GPU than if a 1D IDWT was
used.

> Since i've got exam tomorrow, and a large paper to write, I will be doing
> exactly nil with those ideas - for a week at least.

Oh. Well, don't think about what I wrote... That could consume too much
of your mind.. ;-)



-- 
 / Johan Hanson <[email protected]>

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