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

[Jason Garrett-Glaser]

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.

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