Audio compression: bitrate, format and quality

Audio compression reduces the amount of data required to store or transmit sound. The right setting depends on the source, the destination and whether the file will be edited again.

Lossless and lossy compression

A lossless codec such as FLAC reconstructs the encoded signal exactly. It is useful for archives and working copies.

A lossy codec such as MP3, AAC or Opus discards information according to a psychoacoustic model. This can dramatically reduce file size, but the discarded information cannot be restored later.

Converting a low-quality MP3 to FLAC therefore does not recreate the original recording. It only stores the already degraded signal without introducing another lossless-stage change.

What bitrate means

Bitrate expresses how much data is allocated per second. With lossy codecs, a higher bitrate usually leaves the encoder more room to represent complex sound, but it also creates a larger file.

There is no universal perfect value. Speech, acoustic music and dense electronic music do not stress an encoder in the same way.

Avoid repeated lossy encoding

If you plan to trim, normalize, change speed and then export, keep a high-quality working representation through the intermediate stages. Encode the distribution file once, at the end.

Source → Editing → Normalization → Final lossy encoding

This principle is particularly useful in Workspace pipelines.

Choose according to the destination

For maximum compatibility, MP3 remains practical. AAC is common in modern multimedia environments. Opus is highly efficient for speech and streaming. FLAC is appropriate when preserving the signal matters more than universal playback.

Bethemesh currently writes Opus with FFmpeg’s native CELT-only encoder, without libopus SILK speech mode. Compare your own low-bitrate speech results rather than assuming the usual performance of the complete Opus codec.

The guide MP3, WAV, FLAC, OGG, Opus and M4A: which format should you choose? compares these choices in more detail.

Use the audio compressor when file size is the main constraint, and the audio converter when the primary need is format compatibility.