Convert CAF to MP3

What a CAF file is

Apple introduced the Core Audio Format in 2005 as a flexible container for its own software. Unlike WAV and AIFF, CAF was designed without a 4 GB size ceiling, and it can hold many kinds of sound: uncompressed PCM, AAC, Apple Lossless and more. You'll meet it in:

• recordings and loops from GarageBand and Logic Pro, including Apple Loops,
• iPhone and iPad apps that record or export sound,
• some sound effects and alert sounds made for Apple devices.

On a Mac it plays everywhere. On Windows few programs open it, which is why the usual move is to convert it into something every program understands. The extension is .caf whatever is inside, so the file list in Octoolo is the quickest way to see what you actually have.

Apple Loops also carry tempo and key information that GarageBand and Logic use to fit them into a song. That is Apple-specific data: the MP3 keeps the sound, not those markers, so a converted loop plays at the tempo it was recorded at.

Settings for loops, takes and recordings

A CAF of uncompressed or Apple Lossless sound becomes a 320 kbps MP3 on As it is or High, the most an MP3 holds. That's right for music: loops, instrument takes, a finished song. A spoken recording from an iPhone app is fine at Small: 128 kbps, or 64 for mono. Loops are short, so even at 320 kbps a folder of hundreds stays small: a four-second loop is about 160 KB.

If the CAF already holds AAC, As it is reuses its bit rate, so the MP3 doesn't balloon. Sample rates up to 48 kHz and the channel layout stay as they were; a 96 kHz recording is written at 48 kHz, since MP3 stops there.

Planning to keep producing on Windows? Convert loops to WAV instead, which every music app imports and which loses nothing; the WAV converter page has the settings.

Moving GarageBand or Logic work to Windows

Octoolo converts the audio files themselves, not projects. A GarageBand or Logic project's arrangement, effects and mix stay in that app, so the simplest route is to export a finished mix or the individual tracks from the Mac app first, then convert those files on the PC. If the app lets you export straight to MP3 or WAV, that saves a step; CAF is usually what you end up with when the files come out of a project folder instead.

Once they are MP3s, Octoolo's Audio Editor can lay them out on its four tracks, trim and mix them, and export the result; see the audio joiner for putting several takes in a row. If you'll keep editing, convert to WAV rather than MP3, so each round of changes costs nothing, and make the MP3 only at the very end.

Other Apple sound files

CAF is one of several Apple formats you may find on a Windows PC. M4A files (AAC or Apple Lossless) are covered on M4A to MP3, uncompressed AIFF on AIFF to MP3, and audiobooks on M4B to MP3. They all go into the same converter, so a mixed folder of CAF, AIFF and M4A files can become MP3s in one batch, each at the setting that suits what is inside it.

If the folder also holds video files from the same project, they come along too, since a dropped folder brings in sound and video alike; a video's sound simply becomes an MP3 as well, or you can take it out of the list first.