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Real WebCodecs Encode/Decode

Bandwidth & Resolution Simulator

Your webcam can look great on a local loop and still fall apart on a congested call. This runs your live feed through your browser's actual video encoder and decoder at a chosen bitrate — real codec artifacts, not a fake blur filter — so you can see what you'll actually look like before you lock in a resolution.

Presets

Simulated Connection

Preview

Source vs. Encoded

Raw Source
After Encode → Decode

Readout

Codec Stats

Click "Start Simulator" and choose a connection preset above.

  • Codec In Use:—
  • Target Bitrate:—
  • Achieved Bitrate:—
  • Encoded Resolution:—
  • Round-Trip Latency (encode+decode):—
  • Frames Encoded / Dropped:—

Notes

Why this is a real encode, not a blur filter

The obvious way to fake this would be to apply a blur and call it "low bandwidth." That would be misleading, because bandwidth starvation does not look like blur. It looks like blocking, banding, smeared motion, and colour bleeding — artefacts specific to how video codecs discard information when they run out of bits.

So this tool runs your live feed through your browser's actual video encoder and decoder via the WebCodecs API at the bitrate you select, then shows you the decoded result. The artefacts you see are produced by the same class of codec a video call uses. Where a preset also lowers the resolution, the frame is genuinely downscaled before encoding rather than merely being displayed smaller.

Reading the result

Blocking in flat areasVisible squares across a wall or forehead mean the encoder has run out of bits for smooth gradients — the first thing to degrade.
Smearing when you moveMotion is expensive to encode. If you look fine still but smear when you gesture, your bitrate is marginal rather than adequate.
Loss of fine detail firstHair, patterned clothing, and text on a shirt dissolve before large shapes do. A busy background consumes bits your face would otherwise get.
Colour bleedingColour is usually stored at lower resolution than brightness, so it degrades sooner — often visible around lips and clothing edges.

What this can and cannot tell you

This shows how your image survives a given bitrate. It is not a speed test and does not measure your connection — a separate concern, and one your ISP or a dedicated speed test answers better. Nor does it replicate any specific platform's encoder settings, which are proprietary and change without notice.

What it is genuinely good for is a decision you actually control: whether to simplify a busy background, sit closer, or accept a lower resolution in exchange for a steadier picture. If your image holds together at 800 kbps, a hotel connection will not embarrass you. If it collapses below 4 Mbps, that is worth knowing before an important call rather than during one.

Benchmark Reference

The Six Preset Tiers

BitrateResolutionFrame rateRoughly equivalent to
10 Mbps1080p30 fpsStrong home broadband.
4 Mbps720p30 fpsComfortable typical broadband.
1.5 Mbps720p24 fpsAdequate mobile hotspot / weaker Wi-Fi.
800 kbps480p20 fpsHotel or congested public Wi-Fi.
300 kbps360p15 fpsPoor mobile connection.
120 kbps240p12 fpsVery constrained, worst realistic case.

These are this tool's own real encoder presets — click any one to see your own image at that exact bitrate.

Step-by-Step

How to Run the Test

  1. Click "Start" and allow camera access when prompted.
  2. Pick a preset or drag the bitrate slider to any custom value.
  3. Watch the decoded result — this is a genuine encode/decode round-trip, not a blur filter.
  4. Move and gesture normally to see how motion specifically affects each bitrate tier.

Common Questions

Frequently Asked Questions

How much bandwidth do I need for a video call?
Roughly 1.5Mbps carries 720p and 3Mbps carries 1080p on most platforms, but stability matters more than the peak figure. Use the presets here to see what your own image looks like at each level.
Why does my video look pixelated on calls?
Your connection is running out of bits for the resolution being sent. Blocking in flat areas and smearing during movement are the classic signs, and both are reproduced here at whatever bitrate you choose.
Is this a webcam speed test?
No. It does not measure your connection. It shows how your image survives a given bitrate, which is the part you can actually act on by simplifying your background or lowering resolution.
What resolution should I use on a poor connection?
A steady 720p almost always beats an unstable 1080p, both for you and for everyone watching. Test both here and pick the one that still looks acceptable at your realistic bitrate.
Does this replicate Zoom or Teams exactly?
Not exactly — each platform's encoder settings are proprietary and change without notice. This uses your browser's real video encoder via the WebCodecs API, producing the same class of artifacts any codec produces under bandwidth pressure, which is a reliable general guide even if not a pixel-perfect match to any one platform.