在screcorder上设置videoOrientation时如何避免闪烁？

Question

我目前正在将screcorder库集成到iOS项目中，并且在screcorder上设置videoOrientation属性时遇到了一个问题。在短时间内预览视频似乎闪烁。

我理解这是由于screcorder设置了正确的方向。由于我不希望在更改设备方向时自动调整方向，因此每次按下录制按钮时都会在screcorder上设置方向。

我无法在viewDidLoad上设置方向，因为只能以横向方向录制视频。

- (IBAction)record:(id)sender
{
    if (!_orientationIsSet) {
        UIInterfaceOrientation interfaceOrientation = (UIInterfaceOrientation) [[UIDevice     currentDevice] orientation];
        switch(interfaceOrientation)
        {
        case UIDeviceOrientationPortrait:
            _recorder.videoOrientation = AVCaptureVideoOrientationLandscapeLeft;
            break;

        case UIDeviceOrientationPortraitUpsideDown:
            _recorder.videoOrientation = AVCaptureVideoOrientationLandscapeRight;
            break;

        case UIDeviceOrientationLandscapeLeft:
            _recorder.videoOrientation = AVCaptureVideoOrientationLandscapeRight;
            break;

        case UIDeviceOrientationLandscapeRight:
            _recorder.videoOrientation = AVCaptureVideoOrientationLandscapeLeft;
            break;

        default:
            break;
        };

        _orientationIsSet = YES;
    }

    [_recorder record];
}

感谢任何提示！