[x264-devel] Question about MV initial cost calculation

[Loren Merritt]

On Wed, 17 Nov 2010, Shen Sha wrote:

> I have the following question about the equation 
> "h->cost_mv[lambda][i] = lambda * (log2f(i+1)*2 + 0.718f + !!i) + .5f;"
>
> (1) why the value 0.718 used in the above calculation? Is there any papers/documents which introduce why this number is chosen?
> (2) why the log2f(i+1)*2  is used instead of just log2f(i+1)?  In my opinion, the bit lenght of mv is log2f(i+1), why here this bit length is doubled?

This is the continuous probability distribution to which exp-golomb is a 
discrete approximation. I just took cavlc's mv cost and removed the 
rounding to whole bits.

--Loren Merritt