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Maybe we can get some inspiration in this thread and
this thread ?
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bilu -
Thanks for the ref. I was following that thread at the time but Xvid then still had some bugs relating to custom matrices.
But I'm also diverging from that viewpoint in another way. Most of those custom filters are trying to find an optimum blend of how to smoothly increase the quant factor from low to high frequency components, and this is good.
But there is no free lunch. I'm instead proposing to decide up front how much high frequency detail we are willing to sacrifice (or think is noise and artifacts anyway) and not try to keep it at all. In the worst case this will lose detail on easy to compress still scence but avoids the artifacts that you get with quantizers over 20 or so.
I do this just by setting all the lower diagonals to 255. This will hopefully drive all/most of the values for those high frequences completely to zero in the DCT result. I'd even set them to 9999 if Xvid allowed it, but it doesn't seem to matter.
It would be neat if this could be used with modulated quants somehow.
Koepi - Is this possible?
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Dark- Cracker
could i feel free to add your matrix in my tool ? (i have added support of 9 custom matrix based on the file made by reference divx).
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Dark-Cracker -
Yes, of course. But thanks for asking.
However I've also attached a slightly less extreme case (Filtered_Cutoff_Matrix) that I think works much better. I'm probably going to start using this one for many of my future encodes.
So you might want to try that one first. It's my best so far.
- Tom