Y4M to OPUS Converter
Processing entirely on your device — large files may take a moment.
YUV4MPEG2 Raw Video and Opus Audio 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. Opus delivers the smallest files with the best quality for streaming and messaging.
This converter runs entirely in your browser using WebAssembly — your files never leave your device, nothing is uploaded, and there are no watermarks, sign-ups or queues. Drop in several files at once to convert them as a batch.
How Y4M compares to OPUS
| Y4M | OPUS | |
|---|---|---|
| Compatibility | ffmpeg, x264, vapoursynth | Software strong, hardware lagging |
| Best for | Filter-pipeline interchange | Calls, live streams, chat |
How to convert Y4M to OPUS
- 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 OPUS 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 OPUS format
Opus (IETF RFC 6716, 2012) is the codec that ended the argument: it merges Skype's CELT and Xiph's SILK into one royalty-free format that is simultaneously the best low-latency speech codec and a superb music codec. WebRTC calls, Discord, WhatsApp, WhatsApp calls, YouTube's low-bitrate streams and Zoom all run on it.
At 6 kbps it keeps speech intelligible; at 128 kbps it is transparent for music; latency can dip below 5 ms for live conversation. Its weakness is hardware: dedicated chips and some car/hi-fi devices still lack it, and standalone .opus files are less recognized than MP3 on random devices.
+ Strengths
- ✓Best quality-per-bit across speech and music
- ✓Ultra-low latency — built for live calls
- ✓Royalty-free IETF standard
! Limitations
- −Hardware support still incomplete
- −Not a mastering or archival format
Why convert Y4M to OPUS?
Think of it as moving your file to the container that fits the job. No compression whatsoever OPUS works differently: Best quality-per-bit across speech and music 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 OPUS 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 OPUS?
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.
Does converting Y4M to OPUS 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.
Will the audio track be kept?
Yes. The audio is carried over and re-encoded to the standard audio codec of OPUS, staying in sync with the video. If your Y4M file has multiple audio tracks, the first one is used.