[MPlayer-dev-eng] [PATCH] new video filter : vf_deflicker

[alexandre]

On 16/05/2010 23:53, Reimar Döffinger wrote:

> bzero is deprecated and even removed from the newest POSIX versions.

Fixed.

> Divisions in an inner loop are bad, if you stick with floating point
> they should be multiplications by the inverse instead.
> However, you should not be using floating point after the alogrithmic
> change, you risk accumulating rounding errors.
> It makes more sense to make "means" an int array and do the division
> on use.
> This also allows optimizing special-cases (power of two frame count)
> by using shift if desired later on.

Sorry, means is already an int array. I guess it's OK to do an int 
division in the loop, am I right ?

> Since you don't need h1 anymore there is no need for an extra F1,
> it only causes needeless cache pressure.
> In addition since you only compare the two histograms, the specific
> values are completely irrelevant, thus you should use ints and
> do a simple
> h1[mpi->planes[0][x + mpi->stride[0] * y]]++;
> in the innermost loop.
> I admit it will need changing the histogram matching code a bit.

Good point, I've changed this.

>> +            // histogram matching
>> +            for (n = 0; n<  256; n++) {
>> +                for (k = (n == 0 ? 0 : F1[n - 1]);
>> +                     k<  256&&  F1[n]>  F2[k]; k++);
>> +                L[n] = (k<  255 ? k : 255);
>> +            }
>
> Simpler as
> k = 0;
> for (n = 0; n<  256; n++) {
>      while (k<  255&&  F1[n]>  F2[k]) k++;
>      L[n] = k;
> }

Fixed.

A
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