[FFmpeg-devel] [PATCH] Implement PAFF in H.264

[Martin Zlomek]

On Fri, 12 Oct 2007 02:32:48 +0200, Michael Niedermayer <michaelni at gmx.at>  
wrote:

> On Wed, Oct 10, 2007 at 08:09:11PM +0000, Carl Eugen Hoyos wrote:
>> Martin Zlomek <martin.zlomek <at> email.cz> writes:
>>
>> > > The attached patch fixes chroma motion vectors as specified
>> > > in the h.264 spec in section "8.4.1.4 Derivation process
>> > > for chroma motion vectors", table "Table 8-10 ? Derivation
>> > > of the vertical component of the chroma vector in field
>> > > coding mode".
>>
>> > Previous patch (paff.5.patch) should be replaced be the attached one.
>> > I am not sure if 'emu' flag is updated correctly, but if it is
>> > correct in surrounding code, it is correct in this patch as well.
>> > If anyone (e.g. svn user lorenm) deeply understands edge emulation,
>> > please check this patch.
>>
>> This patch fixes smearing issues in several files I tested.
>>
>> Michael, could you comment?
>
> yes, why does the original code not work?
>
> [...]

The original code alters 'my' depending on mutual relation between the
current macroblock parity and the picture index (in reference picture
list) of the reference macroblock part. Well, I think it is wrong for
MBAFF macroblocks anyway. Or can anybody explain to me how can I
put into relation macroblock parity and picture index, not parity of
the picture at the index? What have I missed?
Anyway, if the reference picture is a frame (neither top field nor
bottom field), no altering should be realized...


-- 
Martin Zlomek
martin.zlomek at email.cz