Mandeep Kumar <mandeep.ku...@linaro.org> writes: >> Vladimir Pantelic <vlado...@gmail.com> writes: >> >> > Mandeep Kumar wrote: >> >> Hi All, >> >> >> >> I have done some benchmarking on OMAP4 running Ubuntu for various >> >> versions of libjpegs. Benchmarks were collected with >> >> modified version of djpeg that prints out ms time taken for decoding. >> >> Sample used for benchmarking is a 12MP image >> >> downloaded from a photography website. Here are the results: >> > >> > ... >> > >> >> libjpeg-turbo trunk version that has NEON patches (5 runs). * >> >> http://libjpeg-turbo.svn.sourceforge.net/viewvc/libjpeg-turbo/* >> >> * Decoding Time for Run 1: 1068 ms >> >> Decoding Time for Run 2: 1065 ms >> >> Decoding Time for Run 3: 1093 ms >> >> Decoding Time for Run 4: 1066 ms >> >> Decoding Time for Run 5: 1067 ms >> >> *Median Decoding Time: 1067 ms* >> > >> > One remark: >> > >> > a 12MP image decoded in 1076ms equals ~12MP/s decoding speed. >> > >> > decoding a 640x480 MJPEG file on a 1GHz OMAP4 using libavcodec >> > gives me an average decoding time per frame of ~10ms which yields: >> > >> > 640x480/10ms = ~30MP/s >> > >> > so roughly 2.5 times faster. >> > >> > Either I am doing something wrong or this libjpeg-turbo is not so turbo. >> >> Libjpeg (turbo or regular) is full of inefficiencies. I guess they all >> add up. >> > My numbers should only be used for relative comparison purpose as djpeg > decoding time that I sent also include time to read input file from > filessystem. Actual decoding speed may be higher when special modification > are done in djpeg application to read input from memory.
I doubt reading from a cached file can account for that much time. Besides, I presume Vladimir was reading his file from somewhere too. However, no matter how slow libjpeg is, that's what lots of apps use, and thus improving it should be beneficial to them insofar jpeg decoding is a bottleneck. -- Måns Rullgård m...@mansr.com _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
