[FFmpeg-devel] DCT coeffs storing order

Germán Milano g.milano87 at gmail.com
Sun Nov 6 15:29:49 CET 2011

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.

Thanks in advance,

More information about the ffmpeg-devel mailing list