Codec 2 is an open source speech codec designed for communications quality speech between 700 and 3200 bit/s. The main application is low-bandwidth HF/VHF digital radio. It fills a gap in open source voice codecs beneath 5000 bit/s and is released under the GNU Lesser General Public License (LGPL). Informal listening tests indicate that Codec 2 at 700 bits/s has better speech quality than MELP and is comparable to TWELP at 600 bit/s. The Codec 2 project also contains several modems (OFDM, FDMDV, COHPSK and mFSK) carefully designed for digital voice over HF radio.

WWW: https://www.rowetel.com/codec2.html
