On Thu, Jun 23, 2011 at 3:30 AM, Christian Robottom Reis <k...@linaro.org> wrote: > Hi there, > > I took a look at the AOSP libjpeg code which is included in > > git://android.git.kernel.org/platform/external/jpeg > > during my flight back home (which incidentally had been diverted and > landed me in Rio de Janeiro; not sure if I celebrate or cry) and noted > the following things: > > - There is a v6 implementation of the fast IDCT algorithm which > lives in armv6_idct.S. > > - The commit which adds this implementation was added October 2010, > and there haven't been any changes since. > > - The code that selects the decoder IDCT implementation in > jddctmgr.c always uses that implementation if ANDROID_ARMV6_IDCT > is defined. > > - Google have an "ashmem" backing store implementation, and have > code to enable tile-based mode. It's a fairly non-intrusive change > to use ashmem since it just replaces jpeg_open_backing_store. > > - The code is pretty much standard libjpeg without any structural > changes to it. > > - There isn't any NEON code in this branch. > > - Mans has an optimized version here: > > http://git.mansr.com/?p=libjpeg;a=summary > > I don't know if he's submitted this to AOSP or not. > > This suggests to me that a simple drop-in of libjpeg-turbo might be > actually easy to do, and that there is probably a significant > performance benefit to be achieved. One thing to keep in mind is that > this code still supports armv6, so we'd probably want to preserve that.
sounds good. Seems like a great starter project for MM WG to get their hands dirty on android. They could have three builds: 1. plain LEB 2. LEB with mans optimized libjpeg 3. LEB with libjpeg-turbo Then benchmark all three and keep AOSP community posted on our intent, progress and results. -- - Alexander _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
