[FFmpeg-devel] [PATCH] get rid of fft_rev

Michael Niedermayer michaelni
Sun Jan 13 02:32:48 CET 2008

On Sun, Jan 13, 2008 at 02:29:00AM +0100, Balatoni Denes wrote:
> Hi!
> Saturday 12 January 2008 19:25-kor Michael Niedermayer ezt ?rta:
> > On Sat, Jan 12, 2008 at 06:50:09PM +0100, Reimar D?ffinger wrote:
> > > Hello,
> > > attached patch gets rid of the global fft_rev array and uses ff_reverse
> > > instead.
> [...]
> >
> > patch ok
> I don't understand one thing though. Speed is always such a big issue here on 
> the list, and this is a change that obviously degrades speed (of course not 
> by much probably). So are there any guidlines for what kind of speed loss is 
> okay, or when is it okay?

it is not certain that it degrades speed, the new table is smaller
thus less data cache is needed
also the if() below likely eats many more cycles than the shift if someone
wants to optimize something

either way benchmarks are welcome if you think its significantly slower now

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Good people do not need laws to tell them to act responsibly, while bad
people will find a way around the laws. -- Plato
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