Align screen-share simulcast default lower layer#1089
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Pull request overview
Aligns Flutter screen-share simulcast/preset defaults with other LiveKit SDKs (JS/Swift/Android): a single low layer derived from the top layer (preserving fps and priorities), and updated preset bitrates for screenShareH720FPS5 and screenShareH1080FPS30.
Changes:
- Rewrote
_computeDefaultScreenShareSimulcastParamsto produce one lower layer at scale 2, inheriting the top layer's framerate and RTP/network priorities, with bitrate = top/scale². - Bumped
screenShareH720FPS5from 400 kbps→800 kbps andscreenShareH1080FPS30from 4 Mbps→5 Mbps. - Added unit tests for the new defaults and a
.changes/entry.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| lib/src/utils.dart | Simplifies default screen-share simulcast to a single half-scale layer that inherits fps and bitrate/network priorities from the original encoding. |
| lib/src/types/video_parameters.dart | Updates two screen-share preset bitrates to match cross-SDK values. |
| test/utils_test.dart | Adds tests verifying preset bitrates and the default low-layer derivation behavior. |
| .changes/align-screenshare-simulcast-defaults | Adds patch changelog entry. |
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cloudwebrtc
approved these changes
May 19, 2026
hiroshihorie
changed the title
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Summary
Align Flutter's generated default lower screen-share simulcast layer with the common SDK behavior.
This updates the default generated lower layer to:
max(150kbps, topLayerBitrate / 4)Also aligns the
screenShareH720FPS5andscreenShareH1080FPS30preset bitrates with the common SDK values.Notes
This does not add the JS-only screen-share presets such as
h360fps15,h720fps30, ororiginal; that broader preset parity work should be handled separately.Tests
dart format --set-exit-if-changed lib/src/types/video_parameters.dart lib/src/utils.dart test/utils_test.dartflutter test test/utils_test.dartflutter analyze --no-pub lib/src/types/video_parameters.dart lib/src/utils.dart test/utils_test.dart