Video decode test. Claimed, then measured.
Whether 4K AV1 or HEVC plays smoothly depends on the decoder the browser gets. This test asks the browser, codec by codec at 1080p and 4K, 30 and 60 fps, whether it offers a hardware decoder, a software one or none, and what its media stack says about smooth and power-efficient playback. Then it encodes a short clip on this page and times how fast each codec decodes it, so the answer is a frame rate, not a flag.
One check · Under a minute
Asks for: Nothing. It runs in its own window and nothing leaves this page.
In short
Video decode test: the answer first
A video decode test asks the browser which decoder it would use for AV1, HEVC, VP9 and H.264, and then times one. This one reads what WebCodecs and Media Capabilities claim at 1080p and 4K, encodes a short clip on the page, and decodes it as fast as it will go, so the answer for each codec is frames per second against the video's own rate.
Reading your result
- Hardware decoder offered
- The browser has a decoder on the graphics chip for that codec and size. The measured rate is usually far above the video's frame rate.
- Software decoder only
- The processor decodes it. Read the measured rate: at 1080p it often keeps up; at 4K 60 it may not, and that is the stutter you see.
- Not measured
- The browser could not encode a clip in that codec, so there was nothing to time. The claims above still say what it would do with one.
What it measures
Measured here, not assumed.
- What WebCodecs claims
- VideoDecoder.isConfigSupported for AV1, HEVC, VP9 and H.264 at four sizes, asked once preferring hardware and once preferring software. In Chrome and Edge, supported when preferring hardware means a hardware decoder is offered.
- What the media stack claims
- MediaCapabilities.decodingInfo: supported, smooth and power efficient, as the browser states them. Smooth and power efficient can be optimistic until the browser has played that kind of video, and power efficient does not promise hardware.
- Measured decode speed
- A 90-frame clip drawn on a canvas and encoded with VideoEncoder in each codec the browser can encode, then decoded as fast as the decoder goes, three times, preferring hardware and then software. The figure is frames per second, the median of the runs.
- Against 30 and 60 fps
- The measured rate over the video's frame rate. Our starting line: 1.5 times the frame rate or more keeps ahead with room to spare; between 1 and 1.5 keeps up with little to spare; under 1 falls behind.
If it fails
The usual failures, and what fixes each.
- No hardware decoder offered for anything
- Hardware acceleration is off or the graphics driver is blocked. The hardware acceleration test shows which, with the switch for your browser. Then install the latest graphics driver.
- HEVC not supported on Windows
- Chrome and Edge use the system's HEVC decoder. Install Microsoft's HEVC Video Extensions from the Microsoft Store, turn hardware acceleration on, restart the browser and check again.
- AV1 only in software
- AV1 hardware decoding needs a recent graphics chip. On an older one the processor decodes AV1, which the measured speed shows keeping up or not at each size. On Windows, install the AV1 Video Extension; on an older laptop, a setting or extension that prefers H.264 or VP9 on video sites helps.
- A laptop with two graphics chips
- In Windows Settings, System, Display, Graphics, set the browser to the chip you want, then restart the browser.
Where a browser stops
What it cannot tell you.
- Which chip decoded the video. The browser does not say, beyond offering a hardware decoder or not.
- The operating system's own player. A native player can use a different decoder path, so a codec missing here may still play there.
- DRM. Whether a streaming service will send 4K depends on its protection level, which this test does not ask about.
- A codec the browser cannot encode. The clip is made on this page; where the browser has no encoder for a codec, its decode speed is not measured, and the claims still are.
- The processor's share of the work. The test times the decoder; it does not measure how busy the processor was meanwhile.
Privacy
Nothing leaves this page.
The camera and microphone are read on this page and stopped as soon as they have been measured. The clip you can play back lives in the browser's memory and is discarded when you leave. The location check discards the position. The internet test sends random bytes to this site and nothing else. The result is stored nowhere unless you ask for it by email, and then only the fact that an email was sent is kept.
Questions
Video decode test, answered
- How do I check if my browser supports AV1 hardware decoding?
- Run the test above. The AV1 rows say whether the browser offers a hardware decoder at 1080p and 4K, and the measured speed shows whether it keeps up at 30 and 60 fps.
- Does Chrome support HEVC?
- On many systems, yes: Chrome and Edge decode HEVC through the system's decoder where the system and graphics chip offer one. On Windows that can need Microsoft's HEVC Video Extensions. This test shows what your browser says on your machine.
- Why does 4K video stutter when the codec is supported?
- Supported can mean a software decoder. If the measured 4K rate is near or below the video's frame rate, the processor is decoding it and cannot keep up. Turn on hardware acceleration and update the driver, or pick a codec the browser decodes in hardware.
- Is anything downloaded or uploaded?
- No. The test clip is drawn and encoded on this page, and nothing leaves it.
- Why does the browser say supported but power efficient no?
- Media Capabilities expects that format to be decoded in software, or has no playback statistics yet. Power efficient is the browser's expectation, not a test of the chip.
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