Re: the basic idea of my codec

Maciek Urbañski wrote:
> The major limatation of those devices is lack of coditional jumps. It's hard
> to perform any adaptive coding whe you can't adapt...
> [...]
> I think (almost sure) it's impossible do do entire decoding process in GPU.
> I can't imagine decoding a Huffam on those machines, and arithetic coders/range
> coders are far more complex... But I might be wrong.

No. The idea is that a GPU perhaps could help with the heavy transforms,
i.e.
the math- and memory-intensive number-crunching.
The CPU would still do all decoding up until the inverse wavelet
transforms.

The adaptive transform that you suggested is next to impossible to
implement
on a GPU because it requires bookkeeping from one coefficient to the
next
and we can not specify the evaluation order.
However, there are other adaptive transforms that don't require
bookkeeping
but that do require conditional jumps.

Your algorithm would be quite complex, because if the adaptivity is
going
to be worthwhile there would have to be many kernels.
Not just different sizes of circles, but also several combinations
of oval-shaped kernels to achieve the same level of adaptivity as
a 1-D transform would.

> And anyway - you can divide the image into separate red and black blocks
> (sort of de-interlave process) and you find that kernel matrix has no
> "holes".

Great.

> But really... why ? why do it on the GPU not CPU ?

If you can, then why not? There would be a substantial performance
boost. 
Hardware support is already widely available, has added value (i.e.
games)
and the price of an able card is reasonable, falling rapidly.

Anyway, this is just a wild thought, not something that I have been
concentrating on.

If you are working on 2-D transform code, please mail it to when it is
functional.
I am trying to find ways to compress wavelet coefficients more
efficiently
and so far I have concentrated on 1-D non-adaptive transforms.
Hmm.. sign prediction is going to be fun ...

Regards.
-- 
 / Johan Hanson <[email protected]>

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