Audio Converter

Audio formats split into two families. Lossy formats — MP3, AAC/M4A, OGG, OPUS — permanently discard sound the encoder judges inaudible, which is how a 50 MB recording becomes a 5 MB file. Lossless formats — WAV and FLAC — keep every sample. FLAC compresses losslessly to roughly half the size of WAV, so it is the better archive format; WAV is uncompressed and mainly useful because every piece of audio software accepts it.

The rule that follows: use lossless while you are still working on audio, and lossy only for the final distributed file. Editing a lossy file and re-exporting it applies the encoder twice, and the artefacts introduced by the first pass get treated as real sound and compressed again. Two or three rounds of this are audible, particularly on cymbals, applause, and reverb tails.

Bitrate decides quality within a lossy format, and the useful thresholds are well established. 96 to 128 kbps is fine for speech — podcasts, lectures, interviews, audiobooks — where the source has limited frequency range anyway and the size saving is worth having. 192 kbps is a sensible general default for music that will be played on phone speakers, earbuds, or in a car. 256 to 320 kbps is the practical ceiling for MP3, and above roughly 256 kbps most listeners cannot reliably distinguish it from the source on ordinary equipment.

One rule saves a lot of wasted space: never encode above the bitrate of the source. Converting a 128 kbps MP3 to 320 kbps does not restore anything. The discarded sound is gone permanently, and the result is the same audio stored in two and a half times the space.

MP3 remains the safe default because everything plays it, including old car stereos and cheap hardware players. It is not the most efficient modern codec, but it is the one that never fails.

M4A (AAC) sounds better than MP3 at the same bitrate and is the native format across the Apple ecosystem and most streaming services. It is the right choice when extracting audio from an MP4, because the audio inside is usually already AAC — exporting to M4A can copy the existing stream rather than re-encoding it, which is faster and avoids a second round of loss.

OPUS is the best-performing codec here by a clear margin, especially below 96 kbps, and it is what voice and video calling uses. Its weakness is hardware support outside browsers and phones. OGG is an open format used in games and by some Linux software. FLAC and WAV are for archiving and editing, not for sending to anyone.