[FFmpeg-devel] DCT coeffs storing order

[Michael Niedermayer]

On Sun, Nov 06, 2011 at 12:29:49PM -0200, Germán Milano wrote:
> Hi everyone,
> I was hoping someone could help me with the following questions:
> 
> When DCT coefficients are stored in the h->mb, in which order are they
> stored? I mean, do the first 256 correspond to luma, then the following
> correspond to one of the chromas, and the final 256 correspond to the
> second chroma component?. In case they're stored like i mentioned, which is
> the order they appear in the array within each component?, e.g., the 256
> luma coeffs are stored in 'raster scan order'?
> 
> 
> Also, it seems h->mb_luma_dc stores values for luma and chroma, since it
> depends of the *p* parameter, which refers to the plane. Is this right? If
> yes, in what order are they stored?
> 
> 
> I printed out the info for an "I" macroblock and this is what I obtained
> (all other coefficients that don't appear have a velue of zero):
> 
>  * CBP = 15
>  * h -> mb_luma_dc[0][0] = 2
>  * h -> mb[82] = -320
> 
> I can't get any conclusions out of these values without knowing the answers
> to my previous questions.. Any help will be truly appreciated.

I suggest you force the whole mb to 0 and then set just 1 element to
non zero and look at what happens to the picture. That way you will
see what each coeff does

Also dont forget that there is intra prediction

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

The greatest way to live with honor in this world is to be what we pretend
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