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

Michael Niedermayer michaelni
Mon Oct 6 12:23:12 CEST 2008


On Mon, Oct 06, 2008 at 01:15:54AM -0700, Jason Garrett-Glaser wrote:
> On Mon, Oct 6, 2008 at 1:03 AM, David Conrad <lessen42 at gmail.com> wrote:
> > On Oct 6, 2008, at 3:42 AM, Jason Garrett-Glaser wrote:
> >
> >> 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.
> >
> > Quoting the Theora spec,
> >
> > LFLIMS - Integer array - 7 bits - Not signed
> >
> > This procedure decodes the table of loop ?lter limit values used to
> > drive the
> > loop ?lter, which is described in Section 6.4.1. It is decoded as
> > follows:
> >
> > 1. Read a 3-bit unsigned integer as NBITS.
> > 2. For each consecutive value of qi from 0 to 63, inclusive:
> > (a) Read an NBITS-bit unsigned integer as LFLIMS[qi ].
> >
> > I can't find anything in the spec that limits it any further.
> 

> Then just fall back to the C code for such utterly absurd bitstreams.

I too think this is the most reasonable solution ...

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Its not that you shouldnt use gotos but rather that you should write
readable code and code with gotos often but not always is less readable
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