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fix: switch backup codec to VP8@30fps, dim H.264 pill with warning

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- Backup codec changed from H.264 (OpenH264, slow) to VP8 (libvpx,
  fast) — same encoder family as VP9, lower dual-encode overhead
- Backup capped at 30fps with proportional bitrate to keep CPU
  overhead low during SIMULCAST dual-encoding
- H.264 pill visually dimmed with amber warning when selected
This commit is contained in:
Jannis Braun
2026-03-24 01:14:47 +01:00
parent a54dd9084a
commit e53d3bcb98
2 changed files with 17 additions and 9 deletions
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packages/web/src/utils/screenShare.ts
+11 -7
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@@ -27,7 +27,7 @@ export interface ScreenShareBuildResult {
videoCodec: 'vp9' | 'h264';
videoEncoding: { maxBitrate: number; maxFramerate: number };
simulcast: false;
backupCodec?: { codec: 'h264'; encoding: { maxBitrate: number; maxFramerate: number } };
backupCodec?: { codec: 'vp8' | 'h264'; encoding: { maxBitrate: number; maxFramerate: number } };
backupCodecPolicy?: BackupCodecPolicy;
};
overdrive: OverdriveOptions;
@@ -131,12 +131,16 @@ export function buildScreenShareOptions(config: ScreenShareConfig): ScreenShareB
const bps = clampedKbps * 1000;
const minBps = Math.round(bps * 0.25);
// VP9: better quality per bit, software-encoded (CPU). Best for text/static content.
// H.264: hardware-encoded via NVENC/QSV/VCE (zero CPU). Universal browser support.
// When VP9 is primary, H.264 SIMULCAST backup handles Safari/incompatible viewers.
// When H.264 is primary, no backup needed — universally supported.
// VP9: better quality per bit via libvpx (software, CPU).
// H.264: OpenH264 software encoder in Electron/Chrome (NOT hardware NVENC).
// When VP9 is primary, VP8 SIMULCAST backup (also libvpx, lightweight) handles
// incompatible viewers (Safari). Backup capped at 30fps to minimize dual-encode overhead.
const useVp9 = config.codec !== 'h264';
// Backup encoding: cap at 30fps and proportional bitrate to keep CPU overhead low
const backupFps = Math.min(fps, 30);
const backupBps = Math.round(bps * (backupFps / fps));
return {
capture: { width: captureWidth, height: captureHeight, frameRate: fps },
publish: {
@@ -145,8 +149,8 @@ export function buildScreenShareOptions(config: ScreenShareConfig): ScreenShareB
simulcast: false,
...(useVp9 ? {
backupCodec: {
codec: 'h264' as const,
encoding: { maxBitrate: bps, maxFramerate: fps },
codec: 'vp8' as const,
encoding: { maxBitrate: backupBps, maxFramerate: backupFps },
},
backupCodecPolicy: BackupCodecPolicy.SIMULCAST,
} : {}),