MP3, WAV, FLAC, M4A and OGG: which audio format to use when
Audio formats confuse people because two different things are bundled into one filename: the container and the codec. A `.m4a` file is an MP4 container holding AAC; a `.ogg` usually holds Vorbis or Opus. What you actually care about is whether the codec throws data away.
Lossless: WAV and FLAC
WAV stores raw PCM samples — a header followed by numbers. It is enormous (about 10 MB per minute of CD-quality stereo) and trivially easy to read and write, which is why almost every browser-based editor exports it. FLAC stores the same samples compressed by roughly 40 to 60 percent with no loss of information; it is the right archive format, but decoding support in editing pipelines is patchier.
Lossy: MP3, AAC and Opus
- **MP3** — universal compatibility, but nothing new should be encoded at 128 kbps in 2026.
- **AAC (.m4a)** — better quality per bit than MP3, the default for Apple devices and most video.
- **Opus** — the strongest of the three at low bitrates and the standard for voice chat; use it when file size matters most.
Each re-encode of a lossy file loses more detail. Edit from the highest-quality source you have, and encode once at the end.
Sample rate and bit depth
Sample rate is how many measurements per second: 44.1 kHz for music, 48 kHz for video, 16 kHz is plenty for speech recognition. Bit depth is how precise each measurement is: 16-bit is fine for delivery, 24-bit gives headroom while editing. Raising either after the fact adds file size, not quality.
Why browser tools export WAV
Browsers ship decoders for nearly everything but expose no encoder for MP3 or AAC. Writing a WAV takes a few dozen lines of JavaScript; writing an MP3 requires shipping a WebAssembly encoder of several megabytes. So the sensible pipeline is: edit locally, export WAV, then run one final conversion if you need a smaller file.
Quick picks
- Voice memo you will transcribe: 16 kHz mono WAV or Opus.
- Podcast delivery: 96–128 kbps mono AAC or MP3.
- Music archive: FLAC.
- Anything you are still editing: WAV or the original untouched file.