private void OnDestroyVideoMixer(String sMediaId) {
   V2Log.d("OnDestroyVideoMixer-->" + sMediaId);
   for (WeakReference<VideoMixerRequestCallback> we : mCallbacks) {
     Object obj = we.get();
     if (obj != null) {
       VideoMixerRequestCallback cb = (VideoMixerRequestCallback) obj;
       cb.OnDestroyVideoMixerCallback(sMediaId);
     }
   }
 }
 private void OnDelVideoMixer(String sMediaId, long nDstUserId, String sDstDevId) {
   V2Log.d("OnDelVideoMixer-->" + sMediaId + "   " + nDstUserId + "   " + sDstDevId);
   for (WeakReference<VideoMixerRequestCallback> we : mCallbacks) {
     Object obj = we.get();
     if (obj != null) {
       VideoMixerRequestCallback cb = (VideoMixerRequestCallback) obj;
       cb.OnDelVideoMixerCallback(sMediaId, nDstUserId, sDstDevId);
     }
   }
 }
  private void OnCreateVideoMixer(String sMediaId, int layout, int width, int height) {
    V2Log.d(
        "OnCreateVideoMixer--> sMediaId :"
            + sMediaId
            + "   "
            + layout
            + "  "
            + width
            + "  "
            + height);

    for (WeakReference<VideoMixerRequestCallback> we : mCallbacks) {
      Object obj = we.get();
      if (obj != null) {
        VideoMixerRequestCallback cb = (VideoMixerRequestCallback) obj;
        cb.OnCreateVideoMixerCallback(sMediaId, layout, width, height);
      }
    }
  }