Y4M to CAF Converter
Processing entirely on your device — large files may take a moment.
YUV4MPEG2 Raw Video and Core Audio Format exist for different jobs: Y4M is uncompressed video with a text header — the interchange format of video-filter pipelines (avisynth/vapoursynth) and encoder test suites. Convert CAF files to WAV or MP3 for use outside the Apple ecosystem.
Because the whole conversion happens on your device, it is instant, unlimited and genuinely private — no accounts, no watermarks, no files on anyone's server. Multiple files are converted in one go.
How Y4M compares to CAF
| Y4M | CAF | |
|---|---|---|
| Structure | YUV4MPEG2 header + FRAME blocks | caff header + chunk table |
| Types / schema | Raw YUV frames | PCM/ALAC/AAC in CAF |
| Compatibility | ffmpeg, x264, vapoursynth | afconvert, Logic Pro, ffmpeg |
| Best for | Filter-pipeline interchange | Apple pro-audio workflows |
How to convert Y4M to CAF
- 1
Select your files
Select your Y4M video.
- 2
Convert instantly
The engine demuxes the container and encodes the audio track into your chosen format.
- 3
Download results
Download the CAF audio — the video track is simply dropped.
About the Y4M format
Y4M (YUV4MPEG2) is uncompressed video with a one-line text header: resolution, framerate and color space, then raw YUV frames. It is the lingua franca of video-filter pipelines — AviSynth, Vapoursynth and encoder test suites pass frames around as Y4M because there is nothing to misparse.
A Y4M of any real length is enormous (30MB per second of 1080p), so conversion to MP4/WEBM with H.264 or VP9 is always the destination — the value is in the zero-ambiguity input, not the format itself.
+ Strengths
- ✓Zero-ambiguity pixel format declaration
- ✓Standard between filter frameworks
- ✓Lossless by construction
! Limitations
- −No compression whatsoever
- −Color space variants (limited/full) trip decoders
- −Not natively playable in browsers
About the CAF format
CAF (Core Audio Format) is Apple's container for pro audio: 64-bit file offsets for recordings of any length, any codec as payload (PCM, ALAC, AAC), and time-stamped MIDI-style event chunks. Logic Pro exports it and macOS system sounds ship in it.
ffmpeg decodes the common PCM/ALAC payload variants, converting CAF to WAV or MP3 for use in any non-Apple DAW, player or web player.
+ Strengths
- ✓64-bit offsets — no size ceilings
- ✓Native to Logic Pro pipelines
- ✓Flexible codec payload
! Limitations
- −Apple-centric — rare outside macOS
- −Some CAF variants (UUID chunks) unsupported
- −Tag metadata Apple-specific
Why convert Y4M to CAF?
Think of it as moving your file to the container that fits the job. No compression whatsoever CAF works differently: 64-bit offsets — no size ceilings If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this Y4M to CAF converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for Y4M to CAF?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Will the audio track be kept?
Yes. The audio is carried over and re-encoded to the standard audio codec of CAF, staying in sync with the video. If your Y4M file has multiple audio tracks, the first one is used.
Does converting Y4M to CAF re-encode my video?
Yes. The video is decoded and re-encoded with the settings chosen by the quality slider, which is what allows the format and size to change. For an archival copy, keep higher quality; for sharing, lower quality gives a much smaller file.