[FFmpeg-devel] Input requested on floating point decomposition for AAC Main

Måns Rullgård mans
Tue Nov 11 12:01:26 CET 2008

Alex Converse wrote:
> To do 16-bit floating point rounding for AAC-Main, I need a function

Do you mean 16-bit half-precision floating-point, or something involving
floating-point numbers and 16-bit integers?

> that will decompose a float into a normalized scheme and it's
> exponent. Conveniently there exists the x87 instruction FXTRACT for
> this very purpose. There are also a variety of standard library
> functions.
> [floating-point madness]
> To me, it seems like the only sane solution is to write assembly for
> x86 and uses the venerable double versions of frexp and ldexp
> elsewhere. Am I missing a better choice?

We should at least use frexpf() where it exists.

M?ns Rullg?rd
mans at mansr.com

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