LPC2478 arm7tdmi 56mhz 8kb cache 32mb ram, jpeg decoding performance
in [ASM]
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From: Alexei A. Frounze on 13 Nov 2009 09:56 On Nov 13, 5:48 am, Herbert Kleebauer <k...(a)unibwm.de> wrote: > Branimir Maksimovic wrote: > > >> He said decoding 800x600 jpeg pictures is very slow. > > > I will if we don;t succeed to achieve time of 5 seconds per > > picture. > > > Damn external memory ;) > > 5 seconds for one 800x600 jpeg? There must be some infinite loop > in the code. 5 secs for a 800x600 pic at 56MHz is ~600 clocks/pixel. A lot, but not insane. I'd suggest to look into the algorithm/implementation and memory I/O. Perhaps some reordering/caching and algo/impl improvements can help. Alex
From: Rod Pemberton on 13 Nov 2009 12:45 "Branimir Maksimovic" <bmaxa(a)hotmail.com> wrote in message news:hd5sr3$coi$1(a)news.eternal-september.org... > ... he said open source c programs for jpeg decoding (from jpeg > site and what he can find) does not give satisfying performance. "JPEG image compression FAQ" listed a few packages. Has he tried them? I've corrected the non-working links. The first two are just different packaging. From the Independent JPEG group: http://www.ijg.org http://www.ijg.org/files/jpegsr7.zip http://www.ijg.org/files/jpegsrc.v7.tar.gz ljpg ftp://ftp.cs.cornell.edu/pub/multimed/ljpg.tar.Z From Stanford mirror, JPEGv1.2.1.tar.Z: http://peipa.essex.ac.uk/ipa/src/formats/jpeg/stanford/ http://peipa.essex.ac.uk/ipa/src/formats/jpeg/ Supposedly, the IJG djpeg is quicker, but it's a much larger package than ljpg. Rod Pemberton
From: Branimir Maksimovic on 14 Nov 2009 08:09
Rod Pemberton wrote: > > Supposedly, the IJG djpeg is quicker, but it's a much larger package than > ljpg. > Thank you. Greets! |