# Codec2

> low-bitrate speech encoding format

**Wikidata**: [Q1105653](https://www.wikidata.org/wiki/Q1105653)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Codec_2)  
**Source**: https://4ort.xyz/entity/codec2

## Summary
Codec2 is a low-bitrate speech encoding format and vocoder used for compressing voice audio. It is free software distributed under the GNU Lesser General Public License, designed to run on Linux and Microsoft Windows. The project is actively maintained, with version 1.2.0 released in July 2023.

## Key Facts
- **License:** GNU Lesser General Public License, version 2.1.
- **Initial Publication Date:** August 2010.
- **Latest Stable Version:** 1.2.0 (released July 24, 2023).
- **Operating Systems:** Linux and Microsoft Windows.
- **Classification:** Lossy audio coding format, vocoder, and free software.
- **Source Code Repository:** GitHub (preferred) and Apache Subversion.
- **Programming Language:** Q15777 (C).
- **Availability:** Packaged for Arch Linux, Debian, Fedora, FreeBSD, Gentoo, Homebrew, macOS (MacPorts), NetBSD, and openSUSE.

## FAQs
### Q: What is Codec2 used for?
A: Codec2 is used for low-bitrate speech encoding, enabling digital voice transmission over narrow bandwidths. It is primarily utilized in amateur radio and other communication systems where bandwidth is limited.

### Q: Is Codec2 free to use?
A: Yes, Codec2 is free software distributed under the GNU Lesser General Public License (LGPL) version 2.1. This allows users to freely run, study, modify, and distribute the software.

### Q: Which operating systems support Codec2?
A: Codec2 is supported on Linux and Microsoft Windows. It is also available for other Unix-like systems through various package managers such as FreeBSD ports, NetBSD packages, and MacPorts.

### Q: What is the latest version of Codec2?
A: The latest stable version is 1.2.0, which was released on July 24, 2023.

### Q: Where can I find the source code for Codec2?
A: The source code is available on GitHub at `https://github.com/drowe67/codec2.git` (preferred) and via Apache Subversion at `https://svn.code.sf.net/p/freetel/code/codec2-dev`.

## Why It Matters
Codec2 addresses the critical need for open-source, low-bitrate speech encoding, particularly in environments where bandwidth is a premium constraint, such as amateur radio (HAM) and digital mobile communications. Unlike proprietary codecs that often require licensing fees and restrict modification, Codec2 is free software under the LGPL v2.1. This openness lowers barriers to entry for developers and hobbyists, fostering innovation in digital voice protocols. Its efficiency allows for voice communication over channels that would otherwise be insufficient for higher-bitrate audio, making digital voice accessible in diverse and resource-constrained scenarios.

## Notable For
- **Open Source Philosophy:** Distributed under the GNU Lesser General Public License (LGPL), ensuring free use and modification.
- **Efficiency:** Designed specifically for low-bitrate speech encoding, making it highly efficient for voice transmission compared to general-purpose audio codecs.
- **Cross-Platform Availability:** Supports Linux and Microsoft Windows, and is accessible via package managers on Arch, Debian, Fedora, Gentoo, FreeBSD, NetBSD, and more.
- **Active Development:** Recent updates include versions 1.1.1 and 1.2.0, both released in 2023.
- **Vocoder Technology:** Classified as a vocoder and lossy audio coding format, optimized for human speech rather than music or general audio.

## Body
### Overview
Codec2 is a low-bitrate speech encoding format designed to compress human speech for efficient digital transmission. It is categorized as a lossy audio coding format and a vocoder. The project was initially published in August 2010.

### Licensing and Source Code
Codec2 is distributed under the **GNU Lesser General Public License, version 2.1**. It is classified as free software, allowing users to run, study, change, and distribute it.
- **Primary Source Repository:** GitHub (`https://github.com/drowe67/codec2.git`)
- **Secondary Repository:** Apache Subversion (`https://svn.code.sf.net/p/freetel/code/codec2-dev`)

### Version History
The project has seen regular updates, with significant releases including:
- **0.1 Alpha:** Early development version.
- **0.9.2:** Released November 11, 2019.
- **1.0.0:** Released August 20, 2021.
- **1.0.5:** Released July 16, 2022.
- **1.1.0:** Released May 4, 2023.
- **1.1.1:** Released June 14, 2023.
- **1.2.0:** Released July 24, 2023.

### Platform and Package Support
Codec2 is compatible with **Linux** and **Microsoft Windows**. It is widely available across various operating systems through their respective package managers:
- **Arch Linux:** `codec2`, `codec2-svn` (AUR)
- **Debian:** `codec2` (stable)
- **Fedora:** `codec2`
- **FreeBSD:** `audio/codec2`
- **Gentoo:** `media-libs/codec2`
- **Homebrew:** `codec2`
- **MacPorts:** `codec2`
- **NetBSD:** `ham/codec2`
- **openSUSE:** `codec2`

### Additional Identifiers
- **Wikipedia:** Available in Danish, German, English, and Polish.
- **Programming Language:** Q15777 (C).
- **Official Website:** `https://rowetel.com/codec2.html`, `https://www.rowetel.com/?page_id=452`

## References

1. [Source](https://www.openhub.net/p/codec2/analyses/latest/languages_summary)
2. [Source](http://www.rowetel.com/blog/?p=839)
3. [Release 0.9.2. 2019](https://github.com/drowe67/codec2/releases/tag/v0.9.2)
4. [2021](https://github.com/drowe67/codec2/releases/tag/v1.0.3)
5. [Release 1.0.0. 2021](https://github.com/drowe67/codec2/releases/tag/v1.0.0)
6. [Release 1.0.1. 2021](https://github.com/drowe67/codec2/releases/tag/v1.0.1)
7. [Release 1.0.5. 2022](https://github.com/drowe67/codec2/releases/tag/v1.0.5)
8. [Release 1.1.0. 2023](https://github.com/drowe67/codec2/releases/tag/v1.1.0)
9. [Release 1.1.1. 2023](https://github.com/drowe67/codec2/releases/tag/v1.1.1)
10. [Release 1.2.0. 2023](https://github.com/drowe67/codec2/releases/tag/1.2.0)
11. [OpenAlex](https://docs.openalex.org/download-snapshot/snapshot-data-format)