[Ffmpeg-devel] [PATCH] Vorbis decoder

Mike Melanson mike
Thu May 12 17:10:11 CEST 2005

Rich Felker wrote:
> I don't believe float is ever faster than a _proper_ int

	The issue, per my understanding, is that these perceptual audio 
decoders need to work with numbers that are larger than 32 bits in 
precision. You either use a float/double and use the CPU's FPU 
instructions or you break the 64-bit number up into 2 32-bit numbers and 
do a little more work to perform, e.g., a multiplication (vs. a single 
FMUL instruction for the floating point data type).

	CPUs without FPU benefit from pure integer implementation since it is 
faster than having to do FP ops in software with integers.

 > implementation, except maybe on broken intel crap (i.e. P4).

	What on Earth makes you call the P4 "broken", smart guy? I remember 
that whole Pentium 1 FDIV bug fiasco, but I can not find similar bugs 
for P4.

>>3.) lavc's fft based imdct is floating point
> Volunteers to fix? :(

	I heard that you were the math major...
	-Mike Melanson

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