[FFmpeg-devel] [PATCH] Move VC1 loop filter to DSPContext

[David Conrad]

On Apr 3, 2009, at 2:42 AM, Kostya wrote:

> On Wed, Apr 01, 2009 at 02:44:13PM -0400, David Conrad wrote:
>>
>> The loop filter is identical to the VC1 spec and the one in the
>> reference implementation.
>> The file I have that uses the loop filter is bitexact to the binary
>> codec for I and P frames, but not B frames.
>> Of the files I have that do not use the loop filter, three are
>> bitexact and one is not bitexact for any frame.
>> The two files that aren't bitexact are from HDDVD rips, so I'll  
>> create
>> a roundup ticket since there's probably some weird feature or
>> something being used.
>
> That may be caused by the fact spec requires 16-bit processing
> (well, 10-bit) because of transform and filtering (loop, overlap) and
> my code uses 8-bit everywhere.
>
> Now I'm a bit far from my computers so I probably look at it in two
> weeks. Roundup ticket will be a good reminder.

I was looking through the code, and it seems that qpel isn't done for  
forward MVs, nor is the rounding flag taken into account  
(vc1_interp_mc() line 1911-1919 of vc1.c). I haven't read the spec to  
see if this is actually correct, but I'll look into this more tomorrow  
unless Kostya beats me to it.