[MPlayer-dev-eng] Re: Vorbis decoding performance

[Balatoni Denes]

Hi!

kedd 08 augusztus 2006 10.07-kor Michael Niedermayer ezeket a bolcs 
gondolatokat fogalmazta meg:
> libavutil/softfloat.c, if its fast on arm then maybe changing the speed
> relevant float code in lavc to a macro based system which can either use
> real floats or soft floats would be interresting, allthough iam not sure
> yet if it would be clean/readable enough for actually being accepted in svn

Once there is a fixed-point mdct, to turn ffvorbis to native fixed point all 
that one needs to do is basically: 
-change the type from float to int32_t
-leave (previously floating point) additions as is
-put in a shift after every (previously floating point) multiplication

And there are not many places in the code where floating point math is 
involved. I don't know how these changes should be implemented, i.e. a macro 
for add and mul, or ifdef two alternatives - but it's an academic question as 
there is no fixed point mdct in ffmpeg unfortunatelly.

bye
Denes

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