[Ffmpeg-devel] H264 decoder internals

[Michael Niedermayer]

Hi

On Saturday 18 June 2005 16:26, M?ns Rullg?rd wrote:
> I'm messing around with the H.264 decoder, and I'm having some trouble
> figuring out how the standard maps to the code.
>
> Around section 8.5.10 in the H.264 spec, there are a number of
> equations similar to 8-339:
>
>   d_ij = (c_ij * LevelScale(qP % 6, i, j) + 2^(3-qP/6)) >> (4 - qP / 6)
>
> I looks like the value of LevelScale() is precomputed for all
> combinations in the dequant_coeff array.  What I'm having some trouble
> with, is understanding where the final value of that equation is
> calculated.  I suppose it's disguised in some clever optimization.
> Could someone please explain what's going on?

dequantization is done during bitstream decoding or during the dc inverse 
transform


-- 
Michael