mpg321 is a completely free clone of mpg123.

mpg321 has been tested to work with gqmpeg.  It should work with
other frontends, but isn't guaranteed.  mpg321 is built on top of
libmad, which was written by Robert Leslie, and is a fully ISO-compliant
MPEG decoder, meaning it's very accurate.  It also operates entirely
within fixed-point arithmetic.

ID3 tags are not supported at all, yet.