On Thu, 12 Mar 2009 02:28:58 -0500 DRC <dcomman...@users.sourceforge.net> wrote:
> I was able to fool the libjpeg/SIMD build into thinking I had an i386 > chip, but it still doesn't want to build the assembly routines: > > make[1]: *** No rule to make target `jsimdcpu.lo', needed by > `libjpeg.la'. Stop. > make[1]: Leaving directory `/home/drc/src/tigervnc/common/jpeg' > make: *** [all] Error 2 > Annoying. I have a 64-bit machine here, so I'll try to have a look at this today and see what needs tweaking. > I was, however, able to port the SIMD code into the VirtualGL build > environment and build it there using the version of libjpeg in the > VirtualGL source tree. From this, I got some good benchmark results and > was then able to use that as a platform to add the Huffman codec > optimizations from TurboJPEG into jchuff.c. > > I am attaching both a spreadsheet of my findings as well as a proposed > patch to jchuff.c. > Feel free to commit. Do you have an optimised version for jdhuff as well? > Performance results: > Without modifications, I found libjpeg/SIMD to be about twice as fast as > the unaccelerated libjpeg but still about 30% slower on compression > than TurboJPEG/OML (the version of TurboJPEG that uses Open mediaLib > Lite.) I suspected that the TurboJPEG Huffman codec was largely > responsible for this performance disparity, so I ported the TurboJPEG > Huffman codec optimizations to the libjpeg/SIMD Huffman codec. The > resulting optimized libjpeg/SIMD met or exceeded the performance of > TurboJPEG/OML in almost all cases. > Fantastic news. openmlib seems to be kicking libjpeg/SIMD's ass when it comes to grayscale data though. I'm not sure how interesting that is for us though. > > Note regarding the patch: > The enhancements borrowed some code from TurboJPEG/OML, so it was > necessary to license the modifications to jchuff.c using the wxWidgets > Library License. This license is fully GPL-compatible, however. > Shouldn't be a problem then. -- Pierre Ossman OpenSource-based Thin Client Technology System Developer Telephone: +46-13-21 46 00 Cendio AB Web: http://www.cendio.com
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