[FFmpeg-devel] [PATCH] PAFF: Derivation process for chroma motion vector

[Carl Eugen Hoyos]

Hi Michael!

Michael Niedermayer wrote:

>>>> Attached is a patch that removes smearing from PAFF test files I use. It
>>>> implements Table 8-10 (Derivation of the vertical component of the
>>>> chroma vector in field coding mode) by only allowing my to be changed if
>>>> the reference picture is a field. (Cosmetic patch will be applied if
>>>> accepted.)
>>>>
>>>> For my sample, it has the same effect as Martin Zlomeks patch: I can't
>>>> see any bottom fields being referenced.
>>> but if fields of different parity will be referenced then its wrong or
>>> am i missing something?
>> If the original code works apart from changing my also for non interlaced
>> reference frames (if h->ref_cache[list][scan8[n]]&1 really shows the parity of
>> the referenced field) it will correctly calculate my += +/- 2
>>
>> I can s/h->ref_cache[list][scan8[n]]/pic->reference
>> but that is a separate issue IMO.
> 
> well if h->ref_cache[list][scan8[n]]&1 where correct in PAFF with the current
> code then your change should not be needed at all
> 
> so no i dont think these are seperate issues
> as far as i understand the issue and i didnt extensively study the current
> h264.c or the h.264 spec, (so i could be wrong) is that
> h->ref_cache[list][scan8[n]]&1 matches field parity in MBAFF but not in PAFF

New patch attached.

Carl Eugen
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