[FFmpeg-devel] [PATCH] avfilter/dctdnoiz: rewrite [f/i]dct

Ronald S. Bultje rsbultje at gmail.com
Mon Aug 4 17:17:29 CEST 2014


On Sun, Aug 3, 2014 at 4:27 PM, Clément Bœsch <u at pkh.me> wrote:

> This removes the avcodec dependency and make the code almost twice as
> fast. More to come.
> The DCT factorization is based on "Fast and numerically stable
> algorithms for discrete cosine transforms" from Gerlind Plonkaa &
> Manfred Tasche (DOI: 10.1016/j.laa.2004.07.015).

I have no comments on the patch itself, but can you explain why we're
re-implementing a custom f/idct rather than using the one provided in
lavcodec? It seems to me that going from fixedpoint/simd'ed to float/c
would be slower, not faster, so there must be more to this patch than what
I'm getting from it...


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