broken MP3 playback in Slackware 9.1

[Adam Myrow]

Somebody mentioned that they were having horribly distorted MP3 playback
under Slackware 9.1.  I hadn't noticed this because I mostly have OGG
Vorbis files, and the times I do play an MP3 file, I use trplayer.
However, I started doing some testing of various MP3 players, and have
come to the conclusion that there must be something wrong with the MAD
library that ships with Slackware 9.1.  Both MPG321 and Madplay use this
library for MP3 playback, and both have seriously messed up audio output.
In the case of MPG321, it is horribly distorted with a steady clicking
sound.  With Madplay, there is a loud hissing noise.  I found that Zinf,
Trplayer, and mpg123 which is in the extra directory all yield correct MP3
playback.  There is also a very simple player called AMP which comes with
Slackware 9.1.  It works correctly as well, but has absolutely no options
other than playing the file.  I.E. no fast-forward, shuffle, etc.  So, any
of those will work.  I don't know if downloading the latest version of the
Mad library would help, but it might.