[FFmpeg-devel] [PATCH] avfilter: add radial and circular blur video filter

[Steinar H. Gunderson]

On Sun, Jul 19, 2020 at 08:20:40PM +0200, Paul B Mahol wrote:
>> If you can explain what you mean the difference between radial and zoom blur
>> is, it would probably be possible to adapt the idea.
> That algorithm is very slow for big lengths, it takes ages to process
> single small image.

Yes, this is the non-recursive version, which is O(n) in the number of
samples. This is why I recommended the recursive version, which is O(log n)
in the number of samples and thus avoids the problem with big lengths.
It is fairly straightforward to convert one to the other.

>> It also has a somewhat more efficient implementation of bilinear filtering
>> than in your patch (three multiplies instead of eight, and also fewer
>> add/sub), although it's likely that a fixed-point implementation would save
>> yet more time if you're interested in trying that.
> Such micro-optimizations could be added any time later.

Sure.

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