[MPlayer-dev-eng] layer2.c + gcc 3.3.1 + -fstrict-aliasing -> 'underwater sound'

Henk Slager henk.slager at home.nl
Thu Dec 18 23:29:47 CET 2003


I am using stock SuSE 9.0 32bit and 64bit on an Athlon64 platform and found
out that software based on mpg123 (e.g. MPlayer-1.0pre2) compiles wrong
if -O2 is used for the whole mpg123 0.59s package. No segfaults or so, but
there is a strong  'underwater soundeffect', especially when the source has
quite some mid-and hi frequencies.

If -O1 and all extra O2 optimisations except -fstrict-aliasing is used, than
it is just right. The problem originates from the file  layer2.c  and thus
affects MPEG1/(S)VCD content. It does not occur with stock SuSE 8.2 (gcc 3.3
20030226 prerelease).

I wonder if the same happens with gcc 3.3.2 or newer; Anyone experienced it
Any tips on how to find the tricky/wrong sourceline or should I blame gcc
3.3.1. ?

Greetz, Henk

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