mpg123 is very popular because of its relative simplicity and its general facility. It is very good at what it does. At the time of mpg321 creation it was, however, under a non-free license: you can't incorporate its code into your own without getting special permission, and commercial entities also need special permission just to use it.
Being a Free Software advocate, I saw a deficiency in the dependency many people had on mpg123. Therefore, I created mpg321.
Please read the document 'INSTALL' to find mpg321's dependencies and configuration, compilation and installation instructions.
mpg321 has been tested on Debian GNU/Linux (x86), as well as Sun Solaris (UltraSparc). It is also available from several BSD vendors, and may be included in other Linux distributions. Any problems encountered on any system, though, should be reported to the author.
If you like mpg321, please donate to the Electronic Frontier Foundation (EFF). They help ensure that software for any purpose can continue to be written legally. Find out more information at http://www.eff.org .
To be informed of any new releases of mpg321, please subscribe to the mpg321-announce mailing list: send an email with 'subscribe' in the body or subject to firstname.lastname@example.org, or visit http://lists.sourceforge.net/lists/listinfo/mpg321-announce.
There are a number of tasks that are still on-going with the develompent of mpg321. If you're interested, please read the TODO and HACKING files. Also, always feel free to e-mail me, Nanakos Chrysostomos email@example.com.
There is also a sourceforge project for mpg321: http://sourceforge.net/projects/mpg321
`mpg321' started long ago (sometime in 1999) as a wrapper script for the mpg123 frontend of the media player FreeAmp. It was contributed to the Debian package of FreeAmp, and for several revisions was included as 'mpg123.freeamp.' (This script has since been removed.)
mpg123.freeamp didn't work very well, and was limited by FreeAmp's implementation of the mpg123 frontend, but it worked for what I needed it to do: play music from the command-line without needing mpg123 installed.
Early in 2001, I decided that a real alternative to mpg123 was needed, and started looking around for a good mp3 decoding library. I came across SMPEG, which was written by Loki Software, and based on SDL. It was very simple programatically and handled most everything that was needed. mpg321 was born, and it did all the simple things that were required of it.
SMPEG, however, required SDL for output, which in turn required many other libraries. This was a very sub-optimal arrangement. So, in 2001, I performed what amounted to almost a full rewrite of mpg321, porting it to Rob Leslie's MAD MPEG audio decoder library. I chose MAD because it provides very high-quality output, and also because it operates entirely with fixed point (integer) instructions.
At the same time, I also switched to the Ogg Vorbis (Xiphophorous) project libao for all audio output.
That's pretty much where mpg321 stands right now. There are still unimplemented features, and undoubtedly still bugs. But it works well for many people, and it liberates one more dependency people had on non-Free software. That's worth it, to me.