在 2007-10-16二的 09:23 +0200，Denis Oliver Kropp写道： > Phil Endecott wrote: > > Dear All, > > > > I have been playing around with the djpeg program (a trivial wrapper > > around libjpeg for decoding) and there is a performance difference of > > about 25% between the defaults and the fastest settings, with no > > noticeable difference in the output (to my eye - no doubt there are > > cases where it can be seen). > > What does it do? 4:4:4 to 4:2:0 reduction while converting to RGB? > > > I'm therefore considering adding some flags to DirectFB so that the > > JPEG provider can be used in different fast/slow modes. Any comments? > > Adding IDirectFBImageProvider::SetOptions() to be called before RenderTo()? > > > I've also noticed that djpeg runs about 15% faster if compiled with -Os > > rather than -O4. > > On x86? > > On embedded architectures, -O2 is often better than -O3, but if you have > a very small instruction cache, -Os could be best.
Its interesting, why -O2 is better? Thanks. Bin _______________________________________________ directfb-dev mailing list [email protected] http://mail.directfb.org/cgi-bin/mailman/listinfo/directfb-dev
