Clean-room implementation of a speech codec

I need a fast, high ratio speech compressor for use in real time VoIP applications. ## Deliverables I am writing a VoIP application, and I need a clean-room inplementation of a fast and efficient voice encoder and decoder. With clean-room I mean an implementation which does not infringe on any copyrights, patents or any other type of intelectual property rights. You may implement existing formats, as long as their specifications are in the public domain. I do not know much about the inner workings of a speech compression codec, so whether you do it in the frequency or time domain or similar doesn't matter in the slightest. I do have a few requirements that need to be met however. 1. The codec must support sampling rates between 8000 and 44100 hZ. I suggest the standard sampling rates of 8000, 11025, 16000, 22050, 32000 and 44100. 2. The codec only needs to accept 16 bit PCM input, in either mono or stereo. Thus, the codec must be able to work with both mono and stereo material. 3. The compression ratio should be at least 10:1 and maintain good quality, but if you could set a quality in the encoder that'd be ideal. I would suggest bitrates between something like 16 and 128 kbps. However, you may definitely go for a variable bitrate solution if it produces better results. 4. The decoder must be able to account for packet loss which is unavoidable, and try to blend the remainning chunks together nicely. Both the encoder and decoder must be able to run in realtime. The code should be written in portable Ansi C, and should compile on any 32 BIT platform that has a standard C compiler. 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows? (depending on the nature? of the deliverables): a)? For web sites or? other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software? installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform Portable Ansi C