notmasteryet/jpgjs — pull request #4 by brendandahl (2011-11-21 00:40:49+00:00)
Title: Switching to a faster IDCT algorithm. Adding benchmark file.

I've ported a much faster IDCT algorithm from poppler. This is the same algorithm that libjpeg also uses for their fast integer IDCT.

Chrome went from ~100ms overall average to ~16ms (84%)
Firefox went from ~146ms to ~58ms (60%)
Firefox nightly went from ~25ms t0 ~9ms (64%)

I also added a little benchmarking page for running the parser multiple times.

PS. I also played around with the floating point version of the fast IDCT, but I found it in general was slower than the integer one. However, it is suppose to be more accurate.