[Flac-dev] success compiling and running under IRIX

Josh Coalson xflac at yahoo.com
Tue Jan 15 07:40:21 PST 2002

--- Martin Blais <blais at discreet.com> wrote:
> 1) i ran it under both linux and irix on the same test file, however,
> the 
> md5sums of the encoded flac files DON'T match. decoding the flac
> files back 
> into original wav files yields files whose md5sums match, regardless
> whether 
> i'm decoding under linux or irix, so that's not a problem. the mips 
> processors are 64-bit processors, perhaps there's something in the
> header? 
> you might want to look into it. it would be nice for flac to produce 
> identical encoded files, regardless of the platform where the files
> were 
> encoded.

the differences are most likely due to the floating point
LPC analysis stage.  different compilations of two key
routines can yield slightly different results even when
both are run on IEEE FP hardware.

the MD5 sum in the metadata should be the same though.

> 3) just for fyi, encoding and decoding on a dual 400Mhz SGI Octane2
> box is 
> noticeably slower than on a 864Mhz P3 PC. that's funny, since FP ops
> are 
> generally much faster under the MIPS machines and normally, mp3
> encoding is 
> much faster on the Octanes.

most of the critical encoder/decoder routines have hand-written
assembly versions for x86 which use SIMD/MMX.  that's probably why.


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