Extract Audio from AVI to CAF — Free Online Tool
Extract audio from AVI video files and save it as a CAF (Core Audio Format) file using PCM 16-bit lossless audio — Apple's professional container designed for high-fidelity audio workflows. This tool is ideal for pulling clean, uncompressed audio from legacy AVI recordings directly into macOS and iOS-compatible pipelines.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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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 commonly store audio encoded with MP3 (libmp3lame) alongside video. During this conversion, FFmpeg discards the video stream entirely and re-encodes the audio into PCM 16-bit little-endian (pcm_s16le) — a lossless, uncompressed format — and wraps it inside Apple's CAF container. If your AVI's audio is already lossy MP3, re-encoding to PCM does not recover lost quality, but it does produce a fully uncompressed representation of what was stored, with no further lossy degradation. CAF's architecture supports files larger than 4GB (unlike WAV/AIFF), making it a robust choice for long audio extractions.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, which is running here as a WebAssembly (FFmpeg.wasm) build entirely inside your browser — no data is sent to a server. |
-i input.avi
|
Specifies the input AVI file. FFmpeg reads the AVI container and identifies its internal streams — typically a video stream (commonly H.264 or MJPEG) and one or more audio streams (commonly MP3). |
-vn
|
Disables all video output, telling FFmpeg to completely ignore and discard the video stream from the AVI. Since the goal is audio-only extraction into CAF, the video data is dropped and not written to the output file. |
-c:a pcm_s16le
|
Sets the output audio codec to PCM signed 16-bit little-endian — uncompressed, lossless audio. This is the default audio codec for CAF in Apple's ecosystem and produces CD-quality audio suitable for archival, editing, or use in macOS/iOS audio tools. |
-b:a 128k
|
Specifies an audio bitrate of 128 kilobits per second. For pcm_s16le this flag has no practical effect since PCM is uncompressed and its bitrate is fixed by sample rate and bit depth rather than a configurable parameter — but it would apply if you switched the audio codec to a lossy option like AAC. |
output.caf
|
Defines the output file as a CAF (Core Audio Format) container. FFmpeg infers the CAF format from the '.caf' extension and writes the extracted, uncompressed PCM audio into this Apple-native container, which supports large file sizes beyond the 4GB limit of WAV or AIFF. |
Common Use Cases
- Extracting the audio track from an old AVI home video or camcorder recording to archive it in a lossless format compatible with macOS audio tools like Logic Pro or GarageBand
- Pulling the audio from an AVI lecture or conference recording for transcription using Apple's speech recognition APIs, which favor CAF input
- Converting AVI game capture footage audio into CAF for use as uncompressed sound effects or voice-over stems in an iOS or macOS game project
- Extracting narration or dialogue from legacy AVI training videos to re-edit and repurpose in Final Cut Pro or other Apple-ecosystem post-production tools
- Archiving audio from AVI broadcast or surveillance recordings in CAF's lossless PCM format to comply with institutional digital preservation standards on Apple infrastructure
- Stripping audio from an AVI music video or live performance file to get a clean, uncompressed audio track for further mixing or mastering in a macOS DAW
Frequently Asked Questions
It depends on what audio codec is inside your AVI file. If the AVI contains MP3 audio (the most common case with libmp3lame-encoded AVIs), the audio was already lossy when it was recorded — converting it to PCM in CAF doesn't introduce any new quality loss, but it also can't restore what was lost in the original MP3 encoding. If your AVI happened to contain AAC or PCM audio, the result in CAF will be an equally faithful representation. The CAF/pcm_s16le output itself is lossless and adds no further compression artifacts.
CAF (Core Audio Format) is Apple's modern successor to both WAV and AIFF, specifically designed to remove their limitations. Unlike WAV and AIFF, CAF has no 4GB file size limit, which matters when extracting long or high-sample-rate audio from large AVI files. CAF with pcm_s16le is natively supported across macOS and iOS, making it the most interoperable lossless choice for Apple-ecosystem workflows without the legacy constraints of the older formats.
CAF is primarily an Apple format and is not natively supported by Windows Media Player or most Linux audio players out of the box. However, tools like VLC, FFmpeg, and some professional DAWs (Reaper, Audacity with plugins) can open CAF files on any platform. If you need broad cross-platform compatibility, you'd be better served extracting to WAV or FLAC instead. CAF is best suited for workflows that stay within macOS, iOS, or professional Apple audio software.
By default, FFmpeg selects the first audio stream it finds in the AVI file, which is typically the primary or only audio track. AVI does support multiple audio tracks, but CAF does not — so only one stream can be written to the output. If your AVI has multiple audio tracks and you need a specific one, you can modify the FFmpeg command by adding '-map 0:a:1' (for the second audio track, zero-indexed) before the output filename to select it explicitly.
The default command uses pcm_s16le, which is uncompressed and has no meaningful bitrate setting — the '-b:a 128k' flag is effectively ignored for PCM. If you want a different codec inside the CAF container, you can replace '-c:a pcm_s16le' with alternatives like '-c:a pcm_s24le' for 24-bit depth, '-c:a flac' for lossless compressed audio (smaller file), or '-c:a aac' followed by '-b:a 256k' for lossy but compact output. CAF supports all of these codecs natively.
Yes. On macOS or Linux, you can use a shell loop to batch process files: 'for f in *.avi; do ffmpeg -i "$f" -vn -c:a pcm_s16le "${f%.avi}.caf"; done'. On Windows Command Prompt, use: 'for %f in (*.avi) do ffmpeg -i "%f" -vn -c:a pcm_s16le "%~nf.caf"'. This is especially useful for archiving a folder of legacy AVI recordings — the browser-based tool is great for single files under 1GB, but the command-line approach handles bulk jobs and larger files with no restrictions.
Technical Notes
AVI files most commonly encode audio using MP3 (via libmp3lame), though some AVIs carry AAC or even PCM audio depending on their origin. This conversion pipeline uses '-vn' to strip all video data, then re-encodes the audio stream to pcm_s16le — 16-bit signed PCM at little-endian byte order — inside the CAF container. PCM 16-bit at standard sample rates (44.1kHz or 48kHz) is CD-quality lossless audio, giving CAF outputs excellent fidelity for archival use. One notable limitation: AVI's audio stream metadata (track titles, embedded tags) is minimal by design and largely not preserved in the CAF output, since AVI metadata handling is non-standardized. Additionally, AVI files sometimes contain VBR MP3 audio with slightly misaligned timing headers; FFmpeg handles this gracefully during extraction, but if you notice sync drift in the output, adding '-fflags +genpts' to the command can help. The '-b:a 128k' flag in the default command has no effect when the target codec is pcm_s16le (PCM is uncompressed and bitrate is determined solely by sample rate and bit depth), but it would take effect if you switched to a codec like AAC or libopus. CAF has no practical file size ceiling, so extracting audio from very long AVI recordings — hours of surveillance or archival footage — is fully supported without file splitting.