[FFmpeg-devel] YUV to RGB conversion, optimized ARM assembler code
Sun Aug 9 06:04:40 CEST 2009
On Sat, Aug 8, 2009 at 1:18 PM, Yonas . <googelly.eyes at gmail.com> wrote:
> Have you looked at the code yet?
My ARM is rusty, but I can comment on the algorithm.
The table look up method avoids multiplies and is the fastest way.
The tables are preclamped, you loose a little quality. If you use
saturating adds (qadd16
sadd16) you can unclamp the tables... allow the values to go from 0 to 0xff.
Otherwise you cant get full black and white.
Its doing 2 rows at a time. You may improve performance doing one row at a
time. x86 does better one row at a time, despite the duplicated UV math.
You can simplify the code by doing just the horizontal loop in ARM and the
outer Y look in C, without loosing much performance. Then it can apply to
422 as well.
ffmpeg uses swscaler for conversion. This wont drop in easily, but it is
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