What Is an Audio Codec?
Updated October 2026
A codec is the method that encodes sound into a file and decodes it back to play. Each codec trades size against quality in its own way, and the container holds the codec and the data.
The short version
- A codec encodes and decodes the sound.
- A container, such as MP4 or MP3, holds the codec and the data.
- Common codecs include AAC, MP3, FLAC and Opus.
- Players and platforms need to support the codec you export.
The short definition
An audio codec is a method for encoding sound into data and decoding it for playback. A codec may be lossy, like MP3 or AAC, or lossless, like FLAC.
Codec and container
The file you see, such as MP4 or MP3, is a container. It holds one or more streams, each with a codec. An MP4 video often carries AAC audio.
Why it matters
A platform may accept some codecs and not others. Check the upload requirements. Export a common codec at a high quality, and keep a lossless master.
In Tunedzy
Exports are WAV, FLAC or MP3 from the master. For a video, the picture is copied and the sound replaced, so the video codec stays as it was.
Export a codec the platform accepts
Tunedzy exports common formats from its master, and copies the picture when it replaces a video soundtrack.
Free tools for this
Frequently asked questions
What is the most common audio codec?
AAC and MP3 are widespread. Check the platform.
Is a codec the same as a format?
Not quite. A format is the file type; a codec is the method inside it.
Does changing codec lose quality?
A lossy codec does. Convert from a lossless master.
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