[Ffmpeg-devel] [PATCH] Vorbis decoder

Mike Melanson mike
Thu May 12 21:49:54 CEST 2005

Rich Felker wrote:
>>	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).
> i find this hard to believe.

	Well, write a program that multiplies int64_t types vs. double data 
types. I don't know the definitive answer either. I am just familiar 
with the conventional knowledge that pure integer implementations do not 
necessarily beat FP implementations in performance.

> this has been discussed extensively by many mplayer (and lavc)
> developers. it sacrifices all the performance issues that are actually
> useful in the real world in order to benchmark high on stupid dsp
> tests, which is pointless because you use a real dsp if you want a
> dsp. essentially the p4 is slow and crippled both as a dsp and as a
> general-purpose cpu. key flaws:

	Okay, so you contend the CPU has flaws. Fair enough. That does not mean 
it is "broken". Broken means "does not work" as opposed to "sub-optimal".

	-Mike Melanson

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