Re: Advanced Motion Compensation for sub 500kbit DVD Video

Lourens Veen wrote:
> A slightly different idea would be to do away with the concept of 
> keyframes, and instead use separate textures that are streamed
> alongside the motion data. This would require a lot of memory for 
> texture caching on the decoder side though, [...]

You don't *need* to encode textures as complete frames.
You *could* cut and paste in the wavelet data, to send regions of 
a keyframe ahead of time.
However, compression would be suffering because of lack of locality
in the data and it would be a little tricky to do, but I believe that it
would still be much better than having only whole keyframes or 3D GOFs.

> My current brilliant idea to create a vector field with motion
> information is to take two (grayscale) frames and create a bunch of
> copies of each. These copies are then gaussian blurred with
> variously sized kernels. [...] We then  repeat the process with a
> sharper version of the two frames, all the way up to a very slightly
> blurred ( to get rid of noise) version of the frames.

I hope you use floats or fixed-point for the blurred images so that
you won't get too many neighbors with the same values.
That algorithm reminds me of Ray Heasman's algorithm that he
described here in March. His images were downsampled.
For each resolution, the motion vectors were upsampled and then refined.   
For downsampled images, he could have used the lowpass subbands from each
wavelet decomposition, that were provided for free!
Up- and down-sampling of an image will displace features, no matter how
good the length of the filter, while gaussian blur will not.

>From what I have experienced from staring like a maniac at wavelet
subbands is that longer minification filters tend to "chisel" out 
features in the image better than short filters.
Do you think that would be good or not, for motion estimation?

Johan



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