[FFmpeg-devel] [PATCH] MMX VP3 Loop Filter

Jason Garrett-Glaser darkshikari
Mon Oct 6 09:42:36 CEST 2008

On Mon, Oct 6, 2008 at 12:35 AM, David Conrad <lessen42 at gmail.com> wrote:
> On Oct 4, 2008, at 2:18 PM, Michael Niedermayer wrote:
>> I'm not sure if this can be done with only 8-bit math; filter_limit can
> theoretically be 127 which pushes CONST0/1 to +- 254, and mm2/mm3 can range
> from -127 to 128.

Are you sure filter_limit can be that large?  I know of no sane
deblocker that allows such high limit values.

Even if it can, you can still do it in byte math; look at x264's
deblocking code for reference.  H.264 requires 9 or 10 bits of
precision for various parts of deblocking, and x264 gets away with
using byte math by emulating the extra bits separately.  This is still
faster than unpacking and doing 16-bit math.

Dark Shikari

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