[FFmpeg-devel] Fwd: Fixpoint FFT optimization, with MDCT and IMDCT wrappers for audio optimization

[Loren Merritt]

On Thu, 23 Aug 2007, Mike Giacomelli wrote:

>> well first part you reduce the number of multiplications split radix would do that
>> but i guess you can make x operations faster by low level optimizations
>> than half of the same operations to which the same low level optimizations
>> could be applied
>
> Most targets without fpus also have very slow integer multiplications
> too.  On ARM for instance, the 32x32->64 multiplies needed to do fix
> point ops can be 4 times slower or more then a simple add as I recall.

As opposed to recent x86 chips, where 32x32 mul is 9 times slower than add?

--Loren Merritt