FormatDrop
Audio Format

CAF

Core Audio Format

CAF (Core Audio Format) is Apple's professional audio container format designed to overcome the 4 GB file size limit of WAV and AIFF while providing flexible codec support. CAF is used by iOS and macOS for long voice recordings, audio development work, and applications that need to store large audio files. CAF files appear as voice recordings from certain iOS apps, outputs from Core Audio framework applications, and in some game audio pipelines targeting Apple platforms.

What is CAF?

CAF is a chunk-based container format that stores audio data alongside extensive metadata: sample rate, channel layout, edit count, marker positions, and user-defined chunks. Unlike WAV and AIFF which use 32-bit file offsets (limiting size to 4 GB), CAF uses 64-bit offsets — enabling files of essentially unlimited size. CAF supports multiple codecs stored in the same container: uncompressed PCM (like WAV), ALAC (Apple Lossless), AAC, MP3, IMA ADPCM, and Apple's proprietary ima4 format used in games. The format is defined by Apple's Core Audio SDK and is natively readable by macOS and iOS without any additional libraries.

CAF pros and cons

Advantages

  • No 4 GB size limit — handles multi-hour recordings without fragmentation
  • Multiple codec support in one container (PCM, ALAC, AAC, MP3)
  • Rich metadata support (markers, regions, loop points)
  • Native macOS and iOS support — no codec installation required on Apple platforms
  • Preserves sample-accurate timestamps for multi-take recording sessions

Limitations

  • Apple-only — no native support on Windows, Linux, or Android
  • Pro Tools and most Windows DAWs don't open CAF natively
  • Not supported in web browsers
  • Rarely needed outside Apple development and iOS app contexts
  • Limited documentation compared to WAV or AIFF

When should you convert CAF files?

Convert CAF to AIFF or WAV for cross-platform audio work and DAW compatibility — most audio tools accept AIFF/WAV but not CAF. Convert to FLAC for compressed lossless storage accessible everywhere. Convert to AAC or MP3 for sharing and streaming. On Mac, afconvert handles CAF natively: `afconvert -f AIFF -d I24LE input.caf output.aiff`.

Convert CAF files

AUDIO-CONVERTER→

All FormatDrop conversions run entirely in your browser — no file upload, no server processing. Your files stay on your device.

CAF FAQ

How do I open a CAF file on Windows or Linux?
VLC plays CAF files on Windows and Linux via software decode. Audacity opens CAF files on all platforms if compiled with Core Audio support — the pre-built version may require a plug-in. Alternatively, use FFmpeg to convert first: `ffmpeg -i input.caf output.wav`, then open the WAV in any audio software. On Windows without VLC or FFmpeg, CAF files are generally not playable natively.
Why does iOS Voice Memos save as CAF?
iOS Voice Memos uses CAF because it can record indefinitely without hitting the 4 GB limit that would truncate a WAV file. A 4-hour stereo recording at 44.1 kHz/16-bit is ~5 GB — safely stored in CAF. When you share a Voice Memo via AirDrop or email, iOS automatically converts it to M4A (AAC) for compatibility. The internal CAF format is transparent to users.
What codec is inside a CAF file?
It depends on the recording application. iOS Voice Memos stores audio as AAC in a CAF container (not uncompressed PCM). Core Audio framework recordings default to uncompressed PCM (like a WAV inside a CAF). Game audio CAF files often use IMA ADPCM or Apple's ima4 codec for fast decoding on older hardware. Check with FFprobe: `ffprobe input.caf` to see the codec inside. If it's uncompressed PCM, conversion to WAV or AIFF is lossless.

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