feat: noise gate implementation

src/state/CallViewModel/localMember/Publisher.ts

@@ -7,6 +7,7 @@ Please see LICENSE in the repository root for full details.
 */
 import {
   ConnectionState as LivekitConnectionState,
+  LocalAudioTrack,
   type LocalTrackPublication,
   LocalVideoTrack,
   ParticipantEvent,
@@ -14,6 +15,7 @@ import {
   Track,
 } from "livekit-client";
 import {
+  combineLatest,
   map,
   NEVER,
   type Observable,
@@ -30,6 +32,17 @@ import {
   trackProcessorSync,
 } from "../../../livekit/TrackProcessorContext.tsx";
 import { getUrlParams } from "../../../UrlParams.ts";
+import {
+  noiseGateEnabled,
+  noiseGateThreshold,
+  noiseGateAttack,
+  noiseGateHold,
+  noiseGateRelease,
+} from "../../../settings/settings.ts";
+import {
+  type NoiseGateParams,
+  NoiseGateTransformer,
+} from "../../../livekit/NoiseGateTransformer.ts";
 import { observeTrackReference$ } from "../../observeTrackReference";
 import { type Connection } from "../remoteMembers/Connection.ts";
 import { ObservableScope } from "../../ObservableScope.ts";
@@ -73,6 +86,8 @@ export class Publisher {
 
     // Setup track processor syncing (blur)
     this.observeTrackProcessors(this.scope, room, trackerProcessorState$);
+    // Setup noise gate on the local microphone track
+    this.applyNoiseGate(this.scope, room);
     // Observe media device changes and update LiveKit active devices accordingly
     this.observeMediaDevices(this.scope, devices, controlledAudioDevices);
 
@@ -400,6 +415,80 @@ export class Publisher {
     });
   }
 
+  private applyNoiseGate(scope: ObservableScope, room: LivekitRoom): void {
+    // Observe the local microphone track
+    const audioTrack$ = scope.behavior(
+      observeTrackReference$(
+        room.localParticipant,
+        Track.Source.Microphone,
+      ).pipe(
+        map((ref) => {
+          const track = ref?.publication.track;
+          return track instanceof LocalAudioTrack ? track : null;
+        }),
+      ),
+      null,
+    );
+
+    let transformer: NoiseGateTransformer | null = null;
+    let audioCtx: AudioContext | null = null;
+
+    const currentParams = (): NoiseGateParams => ({
+      threshold: noiseGateThreshold.getValue(),
+      attackMs: noiseGateAttack.getValue(),
+      holdMs: noiseGateHold.getValue(),
+      releaseMs: noiseGateRelease.getValue(),
+    });
+
+    // Attach / detach processor when enabled state or the track changes.
+    combineLatest([audioTrack$, noiseGateEnabled.value$])
+      .pipe(scope.bind())
+      .subscribe(([audioTrack, enabled]) => {
+        if (!audioTrack) return;
+        if (enabled && !audioTrack.getProcessor()) {
+          const params = currentParams();
+          this.logger.info("[NoiseGate] attaching processor, params:", params);
+          transformer = new NoiseGateTransformer(params);
+          audioCtx = new AudioContext();
+          this.logger.info("[NoiseGate] AudioContext state before resume:", audioCtx.state);
+          // eslint-disable-next-line @typescript-eslint/no-explicit-any
+          (audioTrack as any).setAudioContext(audioCtx);
+          audioCtx.resume().then(() => {
+            this.logger.info("[NoiseGate] AudioContext state after resume:", audioCtx?.state);
+            return audioTrack
+              // eslint-disable-next-line @typescript-eslint/no-explicit-any
+              .setProcessor(transformer as any);
+          }).then(() => {
+            this.logger.info("[NoiseGate] setProcessor resolved");
+          }).catch((e: unknown) => {
+            this.logger.error("[NoiseGate] setProcessor failed", e);
+          });
+        } else if (!enabled && audioTrack.getProcessor()) {
+          this.logger.info("[NoiseGate] removing processor");
+          void audioTrack.stopProcessor();
+          void audioCtx?.close();
+          audioCtx = null;
+          transformer = null;
+          // eslint-disable-next-line @typescript-eslint/no-explicit-any
+          (audioTrack as any).setAudioContext(undefined);
+        } else {
+          this.logger.info("[NoiseGate] tick — enabled:", enabled, "hasProcessor:", !!audioTrack.getProcessor());
+        }
+      });
+
+    // Push param changes to the live worklet without recreating the processor.
+    combineLatest([
+      noiseGateThreshold.value$,
+      noiseGateAttack.value$,
+      noiseGateHold.value$,
+      noiseGateRelease.value$,
+    ])
+      .pipe(scope.bind())
+      .subscribe(([threshold, attackMs, holdMs, releaseMs]) => {
+        transformer?.updateParams({ threshold, attackMs, holdMs, releaseMs });
+      });
+  }
+
   private observeTrackProcessors(
     scope: ObservableScope,
     room: LivekitRoom,
@@ -416,4 +505,5 @@ export class Publisher {
     );
     trackProcessorSync(scope, track$, trackerProcessorState$);
   }
+
 }