Everyday

Convert audio

Pick the file up, hold ⇧, let go toward the format.

Formats

MP3, M4A, AAC, WAV, FLAC, AIFF, OGG and Opus. Each has its own page.

Which to pick:

• MP3 when something has to play it and you do not know what that something is. Nothing refuses an MP3.
• M4A for better quality at the same size, on Apple software.
• WAV or AIFF when handing audio to an editor. Uncompressed, enormous, perfect.
• FLAC to keep something losslessly at about half the size of a WAV.
• Opus for voice at small sizes, if you know the other end supports it.

Lossy into lossy

MP3, M4A, AAC, OGG and Opus are all lossy. Converting between them decodes and re-encodes, and loses a little each time.

Converting an MP3 to FLAC does not restore anything. You get a lossless copy of a lossy file: all of the artefacts, several times the size. If the original is an MP3, it stays an MP3's worth of quality forever.

Audio from a video

Drag the video, hold ⌥, release toward Extract Audio. That is the right way round — converting a video to an audio format on the ⇧ ring does the same job, but Extract Audio is clearer about what it will do to the picture, which is discard it.

Levelling things out

Normalize on the ⌥ ring evens out loudness, so one track is not twice as loud as the next. Useful on a folder of recordings made at different times.

Trimming

Trim cuts the file down to a stretch you pick, and avoids re-encoding what it keeps where the format allows it.