flac dev - Feb 2007 - Encoding discrepancy with flac-1.1.4 on Linux and FreeBSD

A friend and I mirror our music collections on each other's servers; 
between the two of us we have several hundred gigs of flac files.  My 
friend runs Linux, I run FreeBSD.

Recently we started playing with flac-1.1.4 (we had been using flac-1.1.2 
previously) and I noticed something strange.

flac-1.1.4, run with identical options on identical files, produces 
different output on the linux system than it does on the freebsd system.

Here's an example:

linux# uname -r
2.6.20
linux# md5sum 04\ -\ Lilydale.wav
67992fd1e75adb97d6c18180a63c3221  04 - Lilydale.wav
linux# flac -V -8 04\ -\ Lilydale.wav

flac 1.1.4, Copyright (C) 2000,2001,2002,2003,2004,2005,2006,2007  Josh Coalson
flac comes with ABSOLUTELY NO WARRANTY.  This is free software, and you are
welcome to redistribute it under certain conditions.  Type `flac' for
details.

04 - Lilydale.wav: Verify OK, wrote 21657329 bytes, ratio=0.636
linux# md5sum 04\ -\ Lilydale.flac
c7cdebd33293346fc7542c166daac096  04 - Lilydale.flac
linux# flac -dc 04\ -\ Lilydale.flac | md5sum

flac 1.1.4, Copyright (C) 2000,2001,2002,2003,2004,2005,2006,2007  Josh Coalson
flac comes with ABSOLUTELY NO WARRANTY.  This is free software, and you are
welcome to redistribute it under certain conditions.  Type `flac' for
details.

04 - Lilydale.flac: done
67992fd1e75adb97d6c18180a63c3221  -

------

freebsd# uname -r
6.2-STABLE
freebsd# md5 04\ -\ Lilydale.wav
MD5 (04 - Lilydale.wav) = 67992fd1e75adb97d6c18180a63c3221
freebsd# flac -V -8 04\ -\ Lilydale.wav

flac 1.1.4, Copyright (C) 2000,2001,2002,2003,2004,2005,2006,2007  Josh Coalson
flac comes with ABSOLUTELY NO WARRANTY.  This is free software, and you are
welcome to redistribute it under certain conditions.  Type `flac' for
details.

04 - Lilydale.wav: Verify OK, wrote 21657322 bytes, ratio=0.636
freebsd# md5 04\ -\ Lilydale.flac
MD5 (04 - Lilydale.flac) = 9aa5d97f8ff73a271800687bc525608c
freebsd# flac -dc 04\ -\ Lilydale.flac | md5

flac 1.1.4, Copyright (C) 2000,2001,2002,2003,2004,2005,2006,2007  Josh Coalson
flac comes with ABSOLUTELY NO WARRANTY.  This is free software, and you are
welcome to redistribute it under certain conditions.  Type `flac' for
details.

04 - Lilydale.flac: done
67992fd1e75adb97d6c18180a63c3221

------

So, flac 1.1.4, running on two different systems with identical input and 
identical options, produces different output.

But both outputs can be decoded to exactly the same original wav file.

Any idea what might be the cause of this discrepancy?  It's 100% 
reproducible.
-- 
Tod McQuillin

http://flac.sourceforge.net/faq.html#tools__different_sizes

in this case it was probably floating point differences in the
filter construction.

Josh



 
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