Incorrect explanation in documentation of BidirWeight_H264

[eijit]

HI,

The formula that is explained in the following URI seems to be incorrect.

http://software.intel.com/en-us/node/443698

The documentation says,

pDst[x, y] = Clip1c(((pSrc[x, y] * iWeight1 + pSrc2[x, y] * iWeight2 + 2^(ulog2wd - 1)) >> (ulog2wd + 1) + ((iOffset1 + iOffset2 + 1) >>2),

but the correct calculation is as follows:

pDst[x, y] = Clip1c((pSrc[x, y] * iWeight1 + pSrc2[x, y] * iWeight2 + 2^ulog2wd) >> (ulog2wd + 1) ++ ((iOffset1 + iOffset2 + 1) >>1)).

• exponent part (ulog2wd - 1 -> ulog2wd)
• shift value for offset (2 -> 1)
• correspondence of parenthesis

Thanks,

Eijit

[Igor_A_Intel]

Hi Eijit,

you are right, the real formula used in the function is the next:

weighted_sample = ((((Ipp32s)pSrc1[xpos]*iWeight1 + (Ipp32s)pSrc2[xpos]*iWeight2 + (Ipp32s)(1<<ulog2wd))>>(ulog2wd+1))) + ((iOffset1 + iOffset2 + 1)>>1);

so it's just a misprint in the manual - thank you for catching this, will be fixed in the next version of the manual.

regards, Igor