[FFmpeg-devel] [PATCH] unscaled float 2 int conversion

Benjamin Larsson banan
Fri May 16 13:54:46 CEST 2008

Michael Niedermayer wrote:
> [...]
>> What I'm saying is that I think it is irrelevant that the bias trick is 
>> faster on a P3 then lrint because on the P3 we have sse available. Thus 
>> on P3 we can beat the bias trick. What would be interesting is P2 and 
>> lower. But as I don't have access to any machine like that I can't make 
>> any relevant benchmark.
> P3 = P2 + some SIMD
Ok, for the sake of argument I will accept that reasoning. On P2's the 
bias scaling thing will be faster when we have to run float code. My 
argument is then that for those system we shouldn't even run float code, 
we should run fixed point code if we really wanted to have the fastest 
codecs thus we could remove the bias trick from the codecs for the 
benefit of the code clarity. So far we don't have any fixed point code 
that can replace the float code and I don't expect you to agree to my 
arguments so how should we go forward from this when we work on 
implementing a new audio api. The codecs should output samples in their 
native format, that is what I think most of us agree on. But what is the 
native format for a codec outputting samples in float when running in 
simd mode and the same when running in non simd mode ?

Benjamin Larsson

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