[FFmpeg-devel] [PATCH] Lagarith range decoder.

Måns Rullgård mans
Sat Sep 5 18:31:08 CEST 2009

Loren Merritt <lorenm at u.washington.edu> writes:

> On Sat, 5 Sep 2009, Nathan Caldwell wrote:
>> Here's the patch for just the lagarith range decoder. Hopefully I've
>> taken care of anyone's concerns.
> division-free version. 1.5x faster lag_decode_line on Core2.
> +            // FIXME make av_log2 fast so it's usable here
> +            shift = __builtin_clz(range_scaled) - 1;

Right then, how do we fix av_log2 and other common.h functions that
could be optimised?  Using gcc extensions in generic code is

M?ns Rullg?rd
mans at mansr.com

More information about the ffmpeg-devel mailing list