Xine is a free gpl-licensed video player for unix-like systems. It plays mpeg-2 and mpeg-1 system (audio + video multiplexed) streams,
mpeg elementary streams (audio/video only, e.g. mp3 files) and
AVI files (using win32 codec dlls). Xine plays the video and audio data of the stream and synchronizes the playback of both. Depending on the properties of the stream, playback will need more or less processor power, full frame rate for mpeg-2 has been seen on a 400 MHz P II system.

Xine is on 1.1.7 as of June, 2007.

http://xinehq.de/

Mp3stat is Linux a utility program to compare encoders against an MP3 that was VBR encoded. It outputs a linear graphical bitstream analysis of each MP3 being compared and gives you a breakdown of how many frames of each bitrate are found in the MP3. It basically allows you to see how encoders treat areas in the same MP3s differently and lets users discover some of the bitrate effects of different quality levels of the same encoder. Mp3stat also supports Oggs.

Version 2.5.10 of mp3stat is shipping as July 2004.

https://signal-lost.homeip.net/projects/

WMA To MP3 Converter was written for converting WMA to or from MP3/WAV files. So, with WMA to MP3 Converter, you may convert WMA to MP3, convert WMA to WAV, convert WAV to WMA, convert MP3 to WMA.

http://www.wma-to-mp3.net/

The MP3 Streaming DownSampler for PHP is written with cable modem/DSL users with low upstream caps in mind. Using LAME, it dynamically downsamples a requested MP3 to a bitrate which can be streamed. It doesn’t use temporary files, so you don’t have to take the time to do any batching, and you just give it a directory with symlinks to your music in a place the Web server can reach. The interface is simplistic and fast, meant for immediate plug and play access.

http://freshmeat.net/projects/mp3sds

The author says:

This page offers very simple but very useful C source code to parse MP3 files. The parser gives detailed info of each frame in the MP3 file. It presents header info, side info and main data corresponding to each frame in the MP3 file. I was not able to find such a tool on the net so I did it myself and now I want to offer it to the world free of cost.

http://www.vlsiip.com/mp3eater.html

An open source project aiming to create a free codec that supports the MPEG4 LOW and MAIN profiles. Currently available as a command line encoder and Win32 DLL.

Version 1.24 shipped in April of 2004.

http://faac.sourceforge.net/

WinAmp is a very popular freeware MP3 player for Windows PCs.

WinAmp is shipping version 5.0.3 as of March, 2004.

http://www.winamp.com

This is a suite of programs which will help you to convert your existing mp3 files into ogg. The suite includes a text and a graphical frontend. Requires mpg321, mp3info, oggenc, vorbiscomment (zenity for gui).

http://sourceforge.net/projects/mp3toogg/

Roberto Amorim is a familiar and friendly presence on the Hydrogen Audio board. This link points to the many audio compression listening tests he has conducted. These include evaluations of AAC and MP3 encoders at a rew different rates.

http://www.rjamorim.com/test/

A straight-up port of the JavaZoom MP3 library to C#.

http://www.mle.ie/~rob/mp3sharp/index.html

A C# front end for converting WAV files to MP3 format, using the LAME encoder in DLL format.

http://www.codeproject.com/useritems/MP3Compressor.asp

Wouldn’t it be great if there was a free MP3 player written in a portable language like Java? These guys certainly think so.

Version 0.4 was shipping in January, 2004.

DCL user comment: Cool.

http://www.javazoom.net/javalayer/documents.html

A project that aims to hide information in MP3 files.

http://www.petitcolas.net/fabien/steganography/mp3stego/

This app from AbyssMedia is advertised as being able to turn your computer into complete audio recording studio. That means you have the ability to record from external inputs directly to MP3, OGG, WMA, or WAV format. Includes niceties such as MP3 and OGG tag editors, Voice Activated recording, skin support, and more.

Version 6.05 is shipping in November, 2003.

http://www.abyssmedia.com/mp3recorder/index.shtml

This reference page breaks down the structure of an MP3 file quite nicely. Covers all the stuff you’ve wanted to know in detail.

http://www.multiweb.cz/twoinches/MP3inside.htm

With this plugin your copy of Winamp will display track information on an LCD display attached to your PC. Just the thing if you’re looking to set up a jukebox of some kind, maybe in your car. Windows, free.

http://www.markuszehnder.ch/projects/lcdplugin/

This product analyzes and adjusts MP3 files so that they all have the same volume. It appears to be free.

As of Septembery, 2003, Version 1.4.3 is shipping.

http://www.geocities.com/mp3gain/

Billed as a front end for the Lame encoder, LameFE actually supports much more than that on the Win32 platform. Rip CDs, encode using Lame, Monkey’s Audio, or Ogg Vorbis, or playback using a similar batch of codecs.

http://lamefe.sourceforge.net/

It’s a little hard for me to tell what Epigon is selling. They have a nice picture of some kind of board on their front page, but I don’t think they have any hardware for sale. They do appear to have audio codecs for MPEG-1, MPEG-2, and MPEG-4, as well as what appears to be a proprietary speech codec called eSpeech.

Note: Reader Ragu says that despite the problem siwith the web page, he is a big fan of their products. He is a satisfied customer who feels their audio codecs are the best.

http://www.epigonaudio.com/

Damascus Porteng wrote this downsampler that will take an input MP3 stream and resample it at a lower bit rate. Looks like open source that will run on *NIX systems.

http://obfuscated.yi.org/~damacus/Projects/mp3SDS/

A Java library that lets you read and write the ID3 tags embedded in MP3 files. Yep, it’s free.

http://sourceforge.net/projects/yajil

An article on MP3 encoding, pitched to the layman.

http://entertainment.howstuffworks.com/mp3.htm

CoolPlayer is a nice, fast MP3 player targeted to Windows. This Open Source project is a nice piece of work, and the team has created a player that has the features to compete with good commercial players.

Build 214 of CoolPlayer shipped in June, 2003.

http://coolplayer.sourceforge.net/

This product takes your text, converts it to speech, then stores the result in one of several compressed formats, including MP3, Ogg Vorbis, and G.721.

http://www.visual-mp3.com/text-to-speech/

This tutorial provides a useful class that lets you access the ID3 tags hidden in most MP3 files.

http://codeproject.com/useritems/MP3FileInfo.asp

This PHP script reads ID3 tags from MP3 files, as well as tons of other tag types from various other audio and other media files.

http://getid3.sourceforge.net/

Will Pye has a program that cleans up some of the problems associated with VBR encoding in MP3 files.

http://www.willwap.co.uk/Programs/vbrfix.html

An MP3 editor, lets you split and join MP3 files, as well as creating or modifying ID3 tags.

Version 2.40 shipped in April, 2003.

http://www.ezsoftmagic.com/index.htm

This appears to be a tool that is designed to aid you in the process of digitizing your LPs and cassettes to your PC. It will export to MP3 format, which explains its presence here.

http://www.digitope.com/digitalizer/index.htm

WMA MP3 Recorder turns your computer into complete audio recording studio. You can record sound from any internal or external source into WMA/MP3 format sound file directly without use additional disk space.

Version 5.60 is shipping as of April, 2003

http://mp3-wma-recorder.com/