Install codec2 with Homebrew, apk, apt, dnf, MacPorts, Nix, pacman, zypper

Project links

• Homepage
• Repository
• Upstream docs
• Package manager page

Commands and aliases

• c2dec
• c2demo
• c2enc
• c2sim

Project history

David Rowe announced the project on 2009-08-21 in a Rowetel post titled Open Source Low Rate Speech Codec Part 1, describing a plan for a free low-bit-rate speech codec initially targeting 2400 bit/s communications-quality speech. The motivation was explicitly tied to ham radio, low-bandwidth digital radio, and the lack of open sub-5 kbit/s speech codecs.

The current Codec 2 README says the project is C99, LGPL 2.1, and includes the FreeDV API, HF OFDM and FSK modems, FEC, packet-data APIs, and embedded FreeDV support. In July 2023 the repository was refactored, with older code moved to `drowe67/codec2-dev`.

The Rowetel Codec 2 page says the codec fills a gap below 5000 bit/s and integrates with FreeDV, an open-source digital voice protocol that combines modems, codecs, and FEC.

Adoption history

Codec 2 has unusually broad package-manager distribution for a specialized DSP library: the input package facts list Alpine, Homebrew, Debian, Fedora/DNF, MacPorts, Nix, Arch/pacman, Ubuntu, and openSUSE/Zypper. That reflects its use as both a library and a command-line toolkit in radio and audio stacks.

The official FreeDV documentation shows Codec 2 modes inside multiple FreeDV HF and VHF modes from 2012 onward, including 1600, 700C, 700D, 700E, 2400A, and 2400B. This is adoption through an application protocol rather than a standalone end-user CLI alone.

How it is used

The README documents simple command-line workflows with `c2enc`, `c2dec`, `c2demo`, and `c2sim`, including one-liners that encode raw speech, decode it, and play it through ALSA tools. It also documents FreeDV transmit and receive programs, modem programs, LDPC utilities, and build instructions for Linux, Windows cross-compilation, Android, and microcontrollers.

In practice, Codec 2 is used by developers and radio experimenters as a codec library, a set of command-line demonstrations, and the speech-coding component of FreeDV digital voice modes.

Why package nerds care

Codec 2 matters to package maintainers because it is a rare open implementation in the very-low-bit-rate speech codec space, packaged widely despite being specialized DSP software. It brings together C libraries, demo CLIs, radio modem tooling, Octave test/development scripts, embedded targets, and FreeDV protocol support.

It is also a good example of why package histories are not just download counts: the package is important because downstream radio applications, Linux distributions, and experimenters need an auditable open codec where proprietary alternatives such as AMBE and MELP are culturally and legally awkward.

Timeline

• 2009-08-21: David Rowe publicly announces the open-source low-rate speech codec project.
• 2012: FreeDV 1600 mode uses Codec 2 1300 according to the FreeDV mode table.
• 2016: FreeDV 2400A and 2400B VHF modes use Codec 2 1300.
• 2017: FreeDV 700C and 800XA modes use Codec 2 700C.
• 2018: FreeDV 700D uses Codec 2 700C.
• 2020: FreeDV 700E appears in the official FreeDV mode table.
• 2023-07: Current README says the repo was refactored and older code moved to codec2-dev.
• 2023-07-24: Codec2 1.2.0 release published in the current GitHub repository.

Related projects

• FreeDV is the most closely related project and is described by the README and Rowetel page as an open-source digital voice protocol integrating Codec 2, modems, and FEC. The repository also references `codec2-dev` for older code, `drowe67/LPCNet` for FreeDV 2020 support, the SM1000 FreeDV adaptor, and modem components such as OFDM, FDMDV, COHPSK, FSK, and LDPC utilities.

Sources

• https://www.rowetel.com/?page_id=452
• https://www.rowetel.com/blog/?p=128
• https://github.com/drowe67/codec2
• https://github.com/drowe67/codec2/blob/main/README_freedv.md