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Common audio file formats and what they contain
File extensions describe either codecs, containers, or both. The useful question is what stream is inside and what the destination supports.
Reviewed against current browser behavior and AudioFetcher test fixtures on July 28, 2026.
Key facts
MP3 is a lossy codec and familiar file format.
WAV usually contains PCM but can contain other codecs.
M4A is a container commonly used for AAC or ALAC.
FLAC is a lossless codec and format with strong metadata support.
Practical decisions
- Inspect unknown files before converting.
- Keep the original when a conversion would add quality loss.
Measure the source before changing it. Codec, container, duration, channels, and intended playback environment are more useful than choosing a setting from its label alone.
Questions about Common audio file formats and what they contain
What is the short answer to "Common audio file formats and what they contain"?
File extensions describe either codecs, containers, or both. The useful question is what stream is inside and what the destination supports.
Does the linked AudioFetcher tool upload my media?
The local tools linked from this article process selected media in the browser. Read each tool's limits before using a large or uncommon file.
What is the most important practical point?
Inspect unknown files before converting.