Integer DCT/iDCT filter questions

[trbarry]

For lack of anything better I guess I'll go with MfA's explanation above.

But I don't know how to code an efficient mmx implementation of undecimated wavelets. ;) :(

OTOH, the other possibility is I messed up something with this last release. This might be supported by the difference between my Quant 2 test results for my first release and this recent one. I'll go do some more testing.

- Tom

[MfA]

This paper (http://home.student.utwente.nl/m.f.al/E006851770.pdf) describes how to implement a 1D undecimated wavelet transform using relatively short filters, translating that to a MMX implementation shouldnt be too hard :)

If anyone wants to try ... only section II-1 is of import, the rest deals with deblocking and application specific optimizations which wouldnt work for general denoising, although I think performing filtering first entirely in one direction and then in another is a good idea ... the direction sensitivity of the wavelet transform can give annoying artifacts when you use tresholding with a 2D transform. Apart from the transform you still need to apply thresholding, theres a million different ways of doing that though ... easy enough to find a couple of ways on the web (it is sometimes also called coring or shrinkage).

[trbarry]

MfA -

Thanks for the paper but I'm afraid I really have no intuitive grasp of how wavelets work. It took me long enough to understand DCT, to the extent that I even do.

Hopefully one of these days I'll take the time to sit down and figure it out but I suspect it won't be real soon.

How about a nice simple paper explaining why wavelets are better than (i)DCT's. ;)

- Tom

PS - make it even simpler. I think I'm having a stupid week.

[SILICON]

One posible cause for grow filesizes.

The zeroes matrices can make more hard detect the motion.

The more size decresase in the compresion are for the motion vectors, isn't it?

[tangent]

Up.

Any progress with bug finding?
Or perhaps this filter thing should be best done within XviD?

[trbarry]

Sorry, I got involoved with some other things. I'll try to get back to it soon.

- Tom

[odysseus]

as a general rule how does this kind of thing interact with a deinterlacer.

will a smoothing deinterlacer make this filter unnecessary,

and if I run DCTFilter before a deinterlacer will DCTFilter remove some information that the deinterlacer needs, that is, will DCTFilter do some deinterlacing of its own, making the job harder for the "real" deinterlacer?

I've made some test runs putting DCTFilter before and after DG's kernel deinterlacer & can't see a difference on my crappy monitor.

some guidance please.

[trbarry]

I don't know how DG's kernal deint works but generally it is a bad idea to do almost anything before deinterlacing. This would include DctFilter.

- Tom