mac-avcapture: Prevent race condition in source init/deinit

(cherry picked from commit 4fd671e)

Author: jcm93

plugins/mac-avcapture/plugin-main.m

@@ -228,33 +228,36 @@ static void av_capture_destroy(void *av_capture)
     if (!capture) {
         return;
     }
+    /// It is possible that the source's serial queue is still creating this source, so perform destruction
+    /// synchronously on that queue to ensure the source is fully initialized before being destroyed.
+    dispatch_sync(capture.sessionQueue, ^{
+        OBSAVCaptureInfo *capture_info = capture.captureInfo;
 
-    OBSAVCaptureInfo *capture_info = capture.captureInfo;
-
-    [capture stopCaptureSession];
-    [capture.deviceInput.device unlockForConfiguration];
+        [capture stopCaptureSession];
+        [capture.deviceInput.device unlockForConfiguration];
 
-    if (capture_info->isFastPath) {
-        pthread_mutex_destroy(&capture_info->mutex);
-    }
+        if (capture_info->isFastPath) {
+            pthread_mutex_destroy(&capture_info->mutex);
+        }
 
-    if (capture_info->videoFrame) {
-        bfree(capture_info->videoFrame);
-        capture_info->videoFrame = NULL;
-    }
+        if (capture_info->videoFrame) {
+            bfree(capture_info->videoFrame);
+            capture_info->videoFrame = NULL;
+        }
 
-    if (capture_info->audioFrame) {
-        bfree(capture_info->audioFrame);
-        capture_info->audioFrame = NULL;
-    }
+        if (capture_info->audioFrame) {
+            bfree(capture_info->audioFrame);
+            capture_info->audioFrame = NULL;
+        }
 
-    if (capture_info->sampleBufferDescription) {
-        capture_info->sampleBufferDescription = NULL;
-    }
+        if (capture_info->sampleBufferDescription) {
+            capture_info->sampleBufferDescription = NULL;
+        }
 
-    bfree(capture_info);
+        bfree(capture_info);
 
-    CFBridgingRelease((__bridge CFTypeRef _Nullable)(capture));
+        CFBridgingRelease((__bridge CFTypeRef _Nullable)(capture));
+    });
 }
 
 #pragma mark - OBS Module API