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Additionally use browser effective connection type in determining start bitrate - #2149
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…rt bitrate Chromium's navigator.connection.effectiveType catches links with low bandwidth but low latency, which set up quickly and so slip past the connection setup time ramp. The camera x-google-start-bitrate cap is now the lower of the setup time cap and: - 300 kbps for slow-2g and 2g - 500 kbps for 3g - the 1 Mbps ceiling for 4g, and for browsers without the API Screen share stays uncapped. The API's rtt is not used: it lags behind network changes, and the setup time already reflects latency.
changt
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lukasIO and
xianshijing-lk
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October 13, 2026 22:48
🦋 Changeset detectedLatest commit: 5eb9d8a The changes in this PR will be included in the next version bump. This PR includes changesets to release 1 package
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Oct 14, 2026
| */ | ||
| function connectionEffectiveTypeStartBitrateCap(): number { | ||
| // `navigator.connection` is missing from the DOM typings, being Chromium only. | ||
| const connection = (globalThis.navigator as { connection?: { effectiveType?: string } }) |
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fix: do not read globalThis here. The supported browsers (Chrome 64, Firefox 58, Safari 11.1) have no globalThis, and the build adds no polyfill. Use a typeof navigator guard, as the rest of the file does.
| function connectionEffectiveTypeStartBitrateCap(): number { | ||
| // `navigator.connection` is missing from the DOM typings, being Chromium only. | ||
| const connection = (globalThis.navigator as { connection?: { effectiveType?: string } }) | ||
| ?.connection; |
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suggestion: replace the cast with a declared NetworkInformation type, or a package that provides it.
globalThis is missing from supported browsers older than Chrome 71, Firefox 65 and Safari 12.1, and the build does not polyfill it, so reading globalThis.navigator threw a ReferenceError while building the first camera offer on those browsers. Check typeof navigator instead, and type the API with a local NetworkInformation interface in place of the inline cast.
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Builds on #2146, which scales the camera
x-google-start-bitratecap by connection setup time.Problem
Connection setup time grows with round-trip time and loss, so it misses links with low bandwidth but low latency. Those set up quickly and still get the 1 Mbps seed, which overshoots their uplink. In the browser, Chromium's Network Information API reports an effective connection type (
navigator.connection.effectiveType) that does flag such links as3gor slower.Change
The camera cap is now the lower of the setup time cap and a cap from the effective connection type:
effectiveTypeslow-2g,2g3g4g, or no API (Firefox, Safari)connectionEffectiveTypeStartBitrateCap(), applied in one place incomputeTrackStartBitrate.rttis not used. It lags behind network changes, and setup time already reflects latency. Setup time stays the primary signal because every platform has it.Testing
PCTransport.test.ts: caps for each effective type, no cap for4gor withoutnavigator.connection, the lower of the two caps applies, 90% of a target below the cap, and screen share uncapped.npx vitest run src: 920 passed, 1 skipped.