For a long time, I have an awful sound with a mpg123 version > 0.59s-r11 I tried today with the lastest stable mpg123-0.65 but same problem. [edit] I just tried with mpg123, out of asterisk, and I have the same problem with all mp3. [/edit]
An update to mpg123-0.68 or any 1.x version should fix that issue. Reason is the usage of MMX decoder with flexible resampling - solution is _not_to use MMX in that case, which is what newer mpg123 decides now, unless being built _only_ with MMX. That being said, I guess this bug can be closed since gentoo has at least mpg123-1.3 now. Thomas (mpg123 maintainer).
thanks for the tip. please update to the latest mpg123 and reopen if this is still an issue.