chore: made mixer initialization lazy

Author: greenfrvr

ios/RCTWebRTC/Utils/AudioDeviceModule/AudioDeviceModule.swift

@@ -181,7 +181,7 @@ import WebRTC
 
     /// Delegate that receives synchronous input graph configuration callbacks.
     /// Used by `ScreenShareAudioMixer` to modify the engine graph during mixing.
-    @objc public weak var audioGraphDelegate: AudioGraphConfigurationDelegate?
+    @objc public var audioGraphDelegate: AudioGraphConfigurationDelegate?
 
     /// Cached input context from the last `configureInputFromSource` callback.
     /// These allow `startMixing` to configure the graph immediately when the

ios/RCTWebRTC/WebRTCModule.m

@@ -86,12 +86,6 @@ - (instancetype)init {
         RCTLogInfo(@"Using video encoder factory: %@", NSStringFromClass([encoderFactory class]));
         RCTLogInfo(@"Using video decoder factory: %@", NSStringFromClass([decoderFactory class]));
 
-        // Always create the screen share audio mixer eagerly.
-        // It stays dormant (isMixing=false) until startMixing is called.
-        // It will be wired as audioGraphDelegate on the ADM after factory creation.
-        ScreenShareAudioMixer *mixer = [[ScreenShareAudioMixer alloc] init];
-        options.screenShareAudioMixer = mixer;
-
         if (audioProcessingModule != nil) {
             if (audioDevice != nil) {
                 NSLog(@"Both audioProcessingModule and audioDevice are provided, but only one can be used. Ignoring audioDevice.");
@@ -122,10 +116,6 @@ - (instancetype)init {
         _audioDeviceModule = [[AudioDeviceModule alloc] initWithSource:_peerConnectionFactory.audioDeviceModule
                                                       delegateObserver:_rtcAudioDeviceModuleObserver];
 
-        // Wire the mixer as the audio graph delegate so it receives
-        // onConfigureInputFromSource callbacks to modify the engine graph.
-        _audioDeviceModule.audioGraphDelegate = mixer;
-
         _peerConnections = [NSMutableDictionary new];
         _localStreams = [NSMutableDictionary new];
         _localTracks = [NSMutableDictionary new];

ios/RCTWebRTC/WebRTCModuleOptions.h

@@ -4,9 +4,6 @@
 @class InAppScreenCapturer;
 NS_ASSUME_NONNULL_BEGIN
 
-// Forward declare the Swift class — the actual import happens in the .m file.
-@class ScreenShareAudioMixer;
-
 @interface WebRTCModuleOptions : NSObject
 
 @property(nonatomic, strong, nullable) id<RTCVideoDecoderFactory> videoDecoderFactory;
@@ -25,10 +22,6 @@ NS_ASSUME_NONNULL_BEGIN
 /// When YES, in-app screen capture will route .audioApp buffers to the audio mixer.
 @property(nonatomic, assign) BOOL includeScreenShareAudio;
 
-/// The screen share audio mixer instance. Created eagerly during WebRTCModule
-/// init and retained for the lifetime of the module (never cleared).
-@property(nonatomic, strong, nullable) ScreenShareAudioMixer *screenShareAudioMixer;
-
 /// Weak reference to the current in-app screen capturer, set during
 /// `createScreenCaptureVideoTrack` when in-app mode is used.
 @property(nonatomic, weak, nullable) InAppScreenCapturer *activeInAppScreenCapturer;