Jiahao Deng

I have solved this problem by myself.The reason why it crashed is I removed `PixelBufferSource` when the `GLESVideoMixer` was mixing. So I modified function 'GLESVideoMixer:unregisterSource' . ```objc GLESVideoMixer::unregisterSource(std::shared_ptr source) {...

I am so excited to find that you also want to remove a watermark. To do this, I add the belowing function at `VCSimpleSession.mm ` ``` -(void) removePixelBufferSource { m_videoMixer->unregisterSource(m_pixelBufferSource);...

I'm so sorry I have no idea how to do it now, maybe I would implement it in a later version.

因为我是通过`mask`属性去做这个效果的，为了方便我就把箭头做在里面。至于会裁剪这个问题，只要本来的view提前预留空间就好了😅如果你有更好的解决方法，也欢迎交流一下🤝