[FFmpeg-devel] [PATCH] split-radix FFT

Michael Niedermayer michaelni
Fri Aug 8 00:55:48 CEST 2008

On Tue, Aug 05, 2008 at 12:33:43PM +0300, Siarhei Siamashka wrote:
> On Mon, Aug 4, 2008 at 10:27 PM, matthieu castet
> <castet.matthieu at free.fr> wrote:
> > IRRC there was post about wma and cook fixed point implementation that
> > were lot's of faster on such cpu.
> Yes, there was some activity trying to add fixed point audio decoding
> support to FFmpeg (merge some stuff from rockbox).

when? where? by whom?

> But fixed point
> code contributors were required to also implement split-radix FFT for
> FFmpeg as a payload. This kind of 'blackmail' did not work well that
> time, 

Iam not sure what you are talking about, if someone submitted a new FFT
that was suboptimally implemented that certainly was rejected and we should
all be very glad about that as it safes us the work now from removing that
trash again, as lorens split radix FFT will be commited.

if OTOH you are talking about some audio decoder that didnt include or
depend on a fixed point FFT then i simply do not know what you are
talking about.

> so FFmpeg is still absolutely horrible at decoding audio on old
> fpu-less arm cores. Anyway, with split-radix FFT finally getting
> implemented, there may be some hope for FFmpeg to get fixed point
> audio decoding too

not sure, it will require someone actually working instead of the
"there was some activity to build a house but the workers got blackmailed
 into placing a second brick so the stopped working after placing the first"

btw, its off topic but i once optimized tha liba52 imdct in SSE and it
was also rejected because it was based on the c code and wasnt a more
efficient algorithm like split radix. just for the "ohh you are so mean
and other projects are so much better" trolls
projects that knowingly accept trash become trash.

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

While the State exists there can be no freedom; when there is freedom there
will be no State. -- Vladimir Lenin
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