[sldev] OpenJPEG Optimizations

Jason Giglio gigstaggart at gmail.com
Thu Feb 8 09:20:36 PST 2007


Thank you for your reply regarding OpenJPEG licensing.

I do not have the skill currently to help much improving OpenJPEG 
efficiency, but I have gathered up all the information I could find on 
it.  Here is what I have come up with:

https://wiki.secondlife.com/wiki/Openjpeg_improvements

Bushing's profiling shows that the DWT, particularly the 9/7 is where 
the bottleneck is for SL.

Improvements:
Use in-place DWT.
Use lifting implementations rather than the current implementation.
Use SSE/MMX to get a speed increase.

I have found several lifting implementations of 5/3 and 9/7, but it 
seems that all of them are floating point rather than integer.  I don't 
know how useful they would be.

Please coordinate with the SL developers on that wiki page or here on 
the mailing list.  If you could forward this to anyone who has contacted 
you so that we can all work together that would be best.

Thanks.
-Jason


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