CONVERT
Y4M → OPUS
Fast, secure Y4M to OPUS conversion. No registration required.
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Here is the short version — Y4M is a video container, so playback depends on the codec inside as well as the wrapper itself. Hence the need for OPUS. Strip a Y4M down to just its OPUS audio track for playback on devices that cannot (or should not) show video. This is how most audiobook and podcast workflows start — take a Y4M master, emit a OPUS distribution copy, discard the picture track. Keep in mind Y4M is a video container, so playback depends on the codec inside as well as the wrapper itself. And remember that Opus is the modern low-latency royalty-free codec used in VoIP, streaming, and WebRTC.
YUV4MPEG2
Source formatYUV4MPEG2 (Y4M) is a simple uncompressed video format that stores raw YUV pixel data with a minimal header. It is widely used as an intermediate format for video processing and quality benchmarking where no compression artifacts are acceptable.
Opus Audio
Target formatOpus is a versatile, open-source audio codec optimized for both speech and music at very low bitrates. It is the standard for WebRTC voice calls and excels at real-time communication.
Why convert Y4M to OPUS
OPUS is the lingua franca of audio: car stereos, Bluetooth speakers, voice assistants and music apps all expect it. A Y4M cannot be uploaded to most of those ecosystems, but the OPUS you extract today will play anywhere tomorrow.
HOW TO CONVERT
Y4M → OPUS
Start the job
Upload your Y4M; the pipeline auto-detects the audio codec and the best extraction strategy.
Demux to OPUS
FFmpeg pulls the audio track out of the Y4M container and writes a clean OPUS.
Save the result
Click download. The video track never leaves our processing container unmodified — we only returned the audio you asked for.
Common Use Cases
Radio and broadcast
Broadcast automation systems ingest OPUS natively. Hand them a Y4M and they will re-extract anyway — do it upstream with better settings.
Voice assistant training
Custom voice models want clean OPUS audio. Y4M must be demuxed first; doing it here gives you control over bitrate.
Language learning loops
Learners loop short OPUS clips for shadowing. Y4M files make that awkward because the video player pauses too.
Archival audio libraries
Long-term archives store OPUS separately from video masters. Extract once, keep the Y4M as the pristine original.
Y4M vs OPUS — Strengths and limitations
What each format does best, and where it falls short.
Y4M Strengths
- Uncompressed raw YUV — codec benchmark truth.
- Dead-simple header.
- Universal codec development support.
Limitations
- Enormous file sizes.
- Development-only — not for consumption.
- No metadata beyond basic stream params.
OPUS Strengths
- Best-in-class quality across the entire bitrate range.
- Royalty-free and patent-free.
- Ultra-low latency — suitable for live voice and music.
- Handles speech and music equally well — no need to switch codecs.
- Mandatory codec in WebRTC, so supported in every browser by design.
Limitations
- Very low hardware decoder adoption — software-only on most phones.
- Older platforms (legacy Windows apps, old cars) may not play .opus files.
- Container semantics confusing — Opus lives inside Ogg, WebM, or MP4.
Y4M vs OPUS — Technical specifications
Side-by-side comparison of the technical details.
| Specification | Y4M | OPUS |
|---|---|---|
| MIME type | video/x-yuv4mpeg2 | audio/opus |
| Extension | .y4m | — |
| Pixel format | YUV 4:2:0, 4:2:2, 4:4:4 | — |
| Header | ASCII single line | — |
| Extensions | — | .opus, .ogg (container) |
| Standard | — | RFC 6716 (2012) |
| Sample rates | — | 8, 12, 16, 24, 48 kHz |
| Latency | — | 5-60 ms (configurable) |
Y4M vs OPUS — Typical file sizes
Approximate file sizes for common scenarios.
Y4M
- 10 sec 1080p Y4M ~600 MB
- 1 min 4K Y4M ~14 GB
OPUS
- Voice call (24 kbps) 180 KB/min
- Podcast (48 kbps) 21 MB/hour
- Music (128 kbps) ~1 MB/min
- High-fidelity music (160 kbps) ~1.2 MB/min
Quality & Compatibility
Metadata such as track title, artist and chapter markers survive when the Y4M carries them in a form the OPUS supports. If the source Y4M lacks tagging, the OPUS will be untagged — that is not a conversion bug, it is simply the source data.
Tips for Best Results
- For spoken-word content (podcasts, lectures), 64-96 kbps is indistinguishable from higher rates and saves storage dramatically.
- For music, do not drop the OPUS bitrate below the audio bitrate of the source Y4M, otherwise you introduce a second lossy stage.
- Record your extraction settings once and reuse them — consistent bitrate and sample rate across an archive makes downstream tooling happier.
Frequently Asked Questions
Frequently Asked Questions
Yes. The free tier accepts files up to 100 MB without registration, email capture or watermarks. Paid plans raise the size cap, enable batch conversions and provide a REST API for automation, but nothing on the free tier is quality-limited — the output is exactly the same as on any paid plan.
Only if the audio codec inside Y4M is not directly writable into the OPUS container. When codecs match we stream-copy, producing a bit-exact OPUS. When they differ, we re-encode at a high-quality default, so the perceptual loss is tiny for anything other than lossless-to-lossless mismatches.
Uploads run over HTTPS, files are processed in isolated containers, and both the source Y4M and the OPUS output are auto-deleted within two hours. No account is required, file contents are never logged, and KaijuConverter does not use uploads for AI training. The paid plan adds a signable data-processing agreement for regulated workflows.
No. The full Y4M lands in our processing container, we demux the audio locally and then the container is destroyed. The video bytes never leave KaijuConverter infrastructure and auto-delete within two hours along with the original file.
Most files finish in well under a minute. Small images and documents are typically ready in a few seconds; large video or audio files scale roughly with duration. Upload speed from your network is usually the dominant factor, not server time.
Yes. The Advanced options let you set start and end times in HH:MM:SS, so you can extract a single chapter, a specific quote or a clean sample instead of the full duration of the Y4M.
Related comparisons
See these formats side by side to understand which fits your use case best.
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Read guideSecure & Private Conversion
Your files are encrypted during transfer, processed in isolated containers, and automatically deleted within 60 minutes. We never read, share, or store your data.