FLAC is an open source project and we are happy to enlist the help of anyone who wants to contribute. You can do this to a limited extent through the mailing list but if you have major changes to make to the code it's best to sign up as a developer. In either case, make sure to check out the FLAC goals first; there are some thing the we don't want added to FLAC, like copy protection and lossy compression.

There are several areas that are especially important:

• Converging on the bitstream format. This is probably the single most important issue.
• Testing. This is a close second, since if you are a lossless encoder you have to be absolutely lossless for all input. The test suite has patterns that are designed to strain the encoder to the limit but more test cases would definitely help.
• Makefile fixups and code changes to work on more platforms. Both libFLAC and flac are ANSI C and use only the standard C library and math library, meaning ports should not be that difficult. Currently there is a GNU make system and makefiles for MSVC.
• More input plugins. Currently there are plugins for XMMS and Winamp. More is better!
• Speeding up the encoding. Encoding speed at average compression is a little slower than I would like. Improvements to the reference encoder that don't drastically obfuscate the code would be welcome.

Some other "nice-to-haves":

• Improving the compression methods. Some suggestions: on the entropy coding side, try context-modeling the Rice paramter, using general Golomb coding and Huffman coding. On the prediction side, try some other methods for determining the LP coefficients (covariance method, Marple, Burg), or explore other kinds of modeling.
• A faster seek algorithm in the file decoder.
• A stream analyzer that gives useful statistics for tuning or testing new algorithms.
• Fix the MSVC makefiles to make libFLAC.dll (instead of just the .lib).
• Clean up the Winamp2 plugin and/or write a Winamp3 one.
• Configurable ID3V1 support and ID3V2 support in the plugins.
• Support more input types than just WAVE and raw in flac.
• Expand the test suite.
• A better logo! Gimp jedi I'm not...