feat: add manual codec selection (VP9/H.264) to stream settings

VP9 is default — better quality per bit with H.264 SIMULCAST backup
for Safari. H.264 option available for zero-CPU hardware encoding.
Codec choice is independent of gaming/text mode, which still controls
contentHint and degradationPreference.

packages/web/src/components/voice/ScreenShareSettingsPopover.tsx

@@ -20,6 +20,11 @@ const MODES: { value: ScreenShareConfig['mode']; label: string }[] = [
   { value: 'text', label: 'Text' },
 ];
 
+const CODECS: { value: ScreenShareConfig['codec']; label: string; desc: string }[] = [
+  { value: 'vp9', label: 'VP9', desc: 'Less bandwidth, more CPU' },
+  { value: 'h264', label: 'H.264', desc: 'Less CPU, more bandwidth' },
+];
+
 function formatBitrate(bps: number): string {
   return `${(bps / 1_000_000).toFixed(bps % 1_000_000 === 0 ? 0 : 1)} Mbps`;
 }
@@ -178,6 +183,27 @@ export function ScreenShareSettingsPopover({ open, onClose, anchorRef }: ScreenS
           </div>
         </div>
 
+        {/* Codec */}
+        <div>
+          <div className="text-[11px] text-txt-tertiary font-semibold uppercase tracking-wider mb-1.5">
+            Codec
+          </div>
+          <div className="flex gap-1.5">
+            {CODECS.map((c) => (
+              <button
+                key={c.value}
+                onClick={() => setConfig({ codec: c.value })}
+                className={`${pillBase} flex-1 flex flex-col items-center gap-0.5 !py-1.5 ${config.codec === c.value ? pillSelected : pillUnselected}`}
+              >
+                <span>{c.label}</span>
+                <span className={`text-[9px] font-normal ${config.codec === c.value ? 'text-white/70' : 'text-txt-tertiary'}`}>
+                  {c.desc}
+                </span>
+              </button>
+            ))}
+          </div>
+        </div>
+
         {/* Bitrate Override */}
         <div>
           <div className="flex items-center justify-between mb-1.5">

packages/web/src/stores/voiceStore.ts

@@ -10,6 +10,7 @@ export interface ScreenShareConfig {
   height: number | 'native';
   fps: number;
   mode: 'gaming' | 'text';
+  codec: 'vp9' | 'h264';
   customBitrateKbps: number | null;
   shareAudio: boolean;
 }
@@ -145,7 +146,7 @@ export const useVoiceStore = create<VoiceState>()(
       inputDeviceId: 'default',
       outputDeviceId: 'default',
       focusedParticipantId: null,
-      screenShareConfig: { height: 720, fps: 60, mode: 'gaming', customBitrateKbps: null, shareAudio: !isElectron() },
+      screenShareConfig: { height: 720, fps: 60, mode: 'gaming', codec: 'vp9', customBitrateKbps: null, shareAudio: !isElectron() },
       participantVolumes: new Map(),
       setParticipantVolume: (userId, volume) => {
         set((state) => {

packages/web/src/utils/screenShare.ts

@@ -131,33 +131,33 @@ export function buildScreenShareOptions(config: ScreenShareConfig): ScreenShareB
   const bps = clampedKbps * 1000;
   const minBps = Math.round(bps * 0.25);
 
-  // Gaming mode: H.264 primary (hardware NVENC/QSV encoding, zero CPU impact on games)
+  // VP9: better quality per bit, software-encoded (CPU). Best for text/static content.
-  // Text mode: VP9 primary (better compression for sharp text) with H.264 backup for Safari
+  // H.264: hardware-encoded via NVENC/QSV/VCE (zero CPU). Universal browser support.
-  const isGaming = mode === 'gaming';
+  // When VP9 is primary, H.264 SIMULCAST backup handles Safari/incompatible viewers.
+  // When H.264 is primary, no backup needed — universally supported.
+  const useVp9 = config.codec !== 'h264';
 
   return {
     capture: { width: captureWidth, height: captureHeight, frameRate: fps },
     publish: {
-      videoCodec: isGaming ? 'h264' : 'vp9',
+      videoCodec: useVp9 ? 'vp9' : 'h264',
       videoEncoding: { maxBitrate: bps, maxFramerate: fps },
       simulcast: false,
-      // H.264 is universally supported — no backup needed for gaming mode.
+      ...(useVp9 ? {
-      // VP9 needs H.264 backup for Safari/incompatible viewers.
-      ...(isGaming ? {} : {
         backupCodec: {
           codec: 'h264' as const,
           encoding: { maxBitrate: bps, maxFramerate: fps },
         },
         backupCodecPolicy: BackupCodecPolicy.SIMULCAST,
-      }),
+      } : {}),
     },
     overdrive: {
       maxBitrate: bps,
       maxFramerate: fps,
       minBitrate: minBps,
-      degradationPreference: isGaming ? 'balanced' : 'maintain-resolution',
+      degradationPreference: mode === 'text' ? 'maintain-resolution' : 'balanced',
     },
-    contentHint: isGaming ? 'motion' : 'detail',
+    contentHint: mode === 'text' ? 'detail' : 'motion',
   };
 }