[Ffmpeg-devel] Bug in snow revision 1.50 - broken lossless mode

Michael Niedermayer michaelni
Wed Apr 13 12:13:53 CEST 2005


On Wednesday 13 April 2005 06:03, Yartrebo wrote:
> Michael, those rescaled IDWT coefficients (revision 1.50) appear to have
> broken lossless mode quite bad. It's all fuzzy now and is similar in
> quality to quant=10 or 20. It happens for all inputs I've tried.

the regression tests worked yesterday and they do test lossless with the 5/3 
the 9/7 wavelet is with the scaling merged not bijective with fixed point 
numbers, its bijective if rational or real numbers are used, but as the 5/3 
wavelet is superior for lossless (at least it was in my tests) thats really 
but then again, dont hesitate to look at the lifting steps for the 9/7 
wavelet, maybe you can come up with a better solution so that this 
dissadvantage can be avoided


"nothing is evil in the beginning. Even Sauron was not so." -- Elrond

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