Free online AAC to CAF converter

Some Apple audio applications and Core Audio workflows require a .caf file instead of an AAC stream or MPEG-4 audio file. Conversion is also useful when an editor needs uncompressed PCM in a CAF container, or when a project must retain AAC compression while using CAF metadata and file-structure support.

What the AAC format is

AAC (Advanced Audio Coding) is a lossy audio codec used by phones, music services, iTunes, media players, video applications, and portable devices. It normally produces smaller files than uncompressed PCM at a similar perceived quality.

A filename ending in .aac commonly contains an AAC stream in an ADTS layout without a general-purpose container. An .m4a file usually contains AAC inside an MPEG-4 container, while an MP4 file can contain AAC alongside video and other streams. Renaming one extension to another does not convert the file or change its internal structure.

What the CAF format is

CAF (Core Audio Format) is Apple’s flexible audio container, normally identified by .caf. It can hold uncompressed PCM as well as compressed codecs such as AAC, and it supports metadata, channel layouts, varied sample rates, and large or long recordings without some of the size and duration constraints associated with older WAV and AIFF conventions.

CAF is used mainly in macOS, iOS, and Apple-oriented audio workflows. A CAF file containing PCM is generally the better choice for editing, sampling, and DAW work. A CAF file containing AAC remains smaller, but it retains the limitations of lossy compression and may not be accepted by software that supports only PCM CAF.

How to convert AAC to CAF

Using 101convert

1. Open the AAC-to-CAF converter on 101convert.com.
2. Select the source file, such as recording.aac or an AAC-based .m4a file.
3. Choose CAF as the output format and start the conversion.
4. Download the resulting recording.caf and test it in the destination application.

This browser-based option requires no software installation. The resulting CAF codec depends on the converter’s output settings, so inspect the file or test it in the target program when codec compatibility matters.

Using FFmpeg

FFmpeg is suitable for local conversion, automation, and batch processing. To place AAC in a CAF container without another lossy encode, use:

ffmpeg -i recording.aac -c:a copy recording.caf

This copies the AAC stream and changes the container; it does not improve sound quality. To decode the AAC to uncompressed 16-bit PCM, use:

ffmpeg -i recording.aac -c:a pcm_s16le recording.caf

For 24-bit PCM, replace the codec with pcm_s24le. Add -ar 48000 to resample to 48 kHz; omit that option to retain the source sample rate. PCM output is larger, and decoding cannot restore information removed by the original AAC encode.

Using macOS afconvert

macOS includes afconvert, which can create a CAF file with little-endian signed 16-bit PCM:

afconvert -f caff -d LEI16 recording.aac recording.caf

Use afinfo recording.caf to inspect the container, codec, sample rate, channel count, and duration. This method is useful when the destination is a macOS audio application that expects PCM audio.

Quality and compatibility limitations

Container conversion with -c:a copy preserves the existing AAC data but does not increase its quality. Converting to PCM avoids further lossy encoding during later editing, but it creates a larger file and cannot recover detail already discarded by AAC compression.

CAF is a container rather than a single codec specification. An application that accepts the .caf extension may still reject compressed AAC inside CAF, while accepting PCM CAF. Choose PCM for audio editors, samplers, DAWs, and systems that require waveform data; choose copied AAC when compact storage is the priority.

Check the output before importing it with ffprobe recording.caf or, on macOS, afinfo recording.caf. Confirm the codec, sample rate, channel count, and duration, especially when converting an AAC-based .m4a file or a multi-channel recording.