C2 File

What are C2 files and how to open them

Are you having problems opening a C2 file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your C2 files.

What is a C2 file?

A .C2 file is a Codec2 Compressed Audio file.

Codec2 Compressed Audio is a file format for extremely low-bitrate human speech compression using the Codec2 open-source speech codec. It is used when bandwidth is limited or minimal data size is essential, such as in digital voice systems or where voice must be sent over constrained radio or data channels.

Codec2 Compressed Audio files are created by the codec2 encoder program (often invoked as "c2enc") from raw 16-bit PCM audio samples. The encoder produces a packed bitstream which only represents information necessary to reconstruct speech, discarding most other details of the original audio in order to achieve compression at bitrates as low as 700 bits per second. Playback requires using the matching codec2 decoder (like "c2dec") which reads the compressed bitstream and expands it back into a PCM speech waveform.

Internally, these files may include a header when the filename ends with ".c2" which identifies the file as a codec2 stream. The header contains a magic number (to mark the format), version numbers, and a mode identifier (indicating the bitrate mode used such as 3200, 2400, 1600, 700C, etc.). The magic number in this header is the three bytes C0 DE C2 at the start of the file.

How to open C2 files

Important: Different programs may use files with the C2 file extension for different purposes, so unless you are sure which format your C2 file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested two different C2 openers which you will find listed below.

Last updated: August 25, 2026

Various apps that use files with this extension

These apps are known to open certain types of C2 files. Remember, different programs may use C2 files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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File.org helps thousands of users every day, and we would love to hear from you if you have additional information about C2 file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.