Convert AVI to CAF — Free Online Tool
Extract and convert audio from AVI video files into Apple's Core Audio Format (CAF), outputting uncompressed PCM audio at 16-bit depth. CAF's architecture removes the 4GB file size ceiling of older formats, making it ideal for long-form audio extraction from AVI sources in Apple-native workflows.
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FFmpeg Command
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Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
AVI files store interleaved audio and video streams in Microsoft's legacy RIFF-based container. This conversion discards the video stream entirely and extracts only the audio, which is then transcoded into 16-bit signed little-endian PCM (pcm_s16le) and wrapped in Apple's CAF container. Unlike a remux, this is a full audio transcode — the original AVI audio (commonly MP3 via libmp3lame or AAC) is decoded to raw PCM and re-encoded as uncompressed linear PCM. The result is a lossless representation of the audio content at CD-quality resolution, stored in a container designed for Apple's CoreAudio framework. No video data is written to the output file.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool. In the browser-based version of this tool, FFmpeg runs locally via WebAssembly (FFmpeg.wasm) — your AVI file never leaves your device. |
-i input.avi
|
Specifies the input AVI file. FFmpeg parses the RIFF/AVI container to identify and demux the interleaved audio and video streams contained within it. |
-c:a pcm_s16le
|
Sets the audio codec for the output to 16-bit signed little-endian PCM. This fully decodes the compressed audio from the AVI (typically MP3) into uncompressed linear PCM, which is the default and most compatible uncompressed format for CAF files in Apple's CoreAudio stack. |
-b:a 128k
|
Specifies a 128 kbps audio bitrate target. This flag has no practical effect when the codec is pcm_s16le because uncompressed PCM's bitrate is fixed by sample rate and bit depth, not a configurable target — it is included here for consistency with the tool's interface but can be safely omitted for PCM output. |
output.caf
|
Defines the output filename and tells FFmpeg to wrap the decoded PCM audio in Apple's Core Audio Format container. The .caf extension triggers FFmpeg's CAF muxer, which writes the file in a structure natively understood by macOS, iOS, and iPadOS audio frameworks. |
Common Use Cases
- Importing dialogue or soundtrack audio from legacy AVI footage into Logic Pro or GarageBand, which natively consume CAF files without requiring format conversion inside the DAW
- Extracting uncompressed audio from AVI archival recordings for mastering workflows on macOS, where CAF's large file support prevents truncation of hour-long recordings
- Preparing audio assets from AVI game cutscene files for use in Apple platform apps or games via AudioToolbox, which treats CAF as a first-class citizen
- Converting AVI-packaged field recordings from older video cameras into CAF for use in Final Cut Pro audio roles or as reference tracks in a ProTools session on macOS
- Stripping audio from AVI surveillance or dashcam footage to produce an uncompressed CAF file for forensic audio analysis tools running on Apple hardware
- Decoding the compressed MP3 audio track common in legacy AVI files to uncompressed PCM inside CAF, eliminating generation loss before further audio editing or processing
Frequently Asked Questions
It depends on the audio codec inside your AVI file. If the AVI contains MP3 or AAC audio (the most common cases), those compressed streams are fully decoded and then stored as uncompressed 16-bit PCM in the CAF output. The decode-to-PCM step itself introduces no additional loss, but you cannot recover information that was already discarded by the original lossy compression. If your goal is a pristine lossless copy, the PCM output in CAF is as faithful to the decoded signal as possible.
AVI files most commonly store audio as MP3, which achieves roughly a 10:1 compression ratio over uncompressed audio. The CAF output uses pcm_s16le, which is completely uncompressed linear PCM — the same raw format used on audio CDs. A one-hour AVI with a 128 kbps MP3 audio track might have roughly 56 MB of audio data, whereas the equivalent uncompressed 16-bit stereo PCM in CAF would be around 600 MB. This is expected and is the cost of working with uncompressed audio.
Yes. CAF with PCM audio is fully supported by Apple's CoreAudio and AVFoundation frameworks across iOS, iPadOS, and macOS. However, PCM audio files can be very large, which may be a concern for mobile distribution. If storage size matters, you could modify the FFmpeg command to use the AAC codec instead (replacing pcm_s16le with aac) while keeping the CAF container, which Apple devices also support natively.
No. CAF does not support multiple audio tracks within a single file, and by default FFmpeg maps only the first audio stream from the AVI source. If your AVI contains multiple audio tracks (such as multiple language dubs, which some AVI files support), only the first track will be extracted. You would need to run separate FFmpeg commands with explicit stream mapping (using -map 0:a:1, etc.) to extract each track individually into its own CAF file.
The -b:a 128k flag in this command is technically present but has no effect on pcm_s16le output, since uncompressed PCM has a fixed bitrate determined by sample rate and bit depth rather than a configurable bitrate target. To use a compressed codec, replace -c:a pcm_s16le with -c:a aac and the -b:a 128k flag will then control the AAC encoder's target bitrate. For example: ffmpeg -i input.avi -c:a aac -b:a 192k output.caf produces a smaller compressed CAF file.
Yes. On macOS or Linux you can use a shell loop: for f in *.avi; do ffmpeg -i "$f" -c:a pcm_s16le "${f%.avi}.caf"; done. On Windows Command Prompt: for %f in (*.avi) do ffmpeg -i "%f" -c:a pcm_s16le "%~nf.caf". This processes each AVI in the current directory and creates a matching CAF file, which is especially useful when dealing with large batches that exceed the 1 GB browser limit.
Technical Notes
AVI's RIFF-based structure caps individual chunk sizes at 4 GB and stores audio interleaved with video frames, which necessitates full container parsing and demuxing before the audio stream can be extracted. The audio codec inside AVI files varies widely — libmp3lame (MP3) is overwhelmingly common in legacy files, but some AVI files carry AAC or PCM audio. Regardless of source codec, this command fully decodes the compressed audio and re-encodes it as pcm_s16le, which is 16-bit signed little-endian linear PCM at the source file's native sample rate (typically 44100 Hz or 48000 Hz). CAF was specifically designed by Apple to solve the 4 GB file size limitation of AIFF and WAV, making it well-suited for very long audio extractions. Note that CAF is essentially Apple-proprietary: it is not natively supported by most Windows or Linux media players, so CAF output is best treated as a production-stage format within an Apple ecosystem workflow rather than a distribution format. Subtitles and chapter markers from the AVI (rarely present, as AVI has no native subtitle support) are not carried over. The -b:a 128k flag has no functional effect on PCM output and can be omitted when running this command locally.