When recording video, how to set transformation (portrait, landscape, etc.) for video?

Should I use AVCaptureConnection's videoOri开发者_开发知识库entation property, or set the transform property of the videoWriterInput, or something else?

Seems like AVCaptureConnection's videoOrientation property sets the orientation as it's recording, while the transform property of the videoWriterInput will set a flag for the playback transform.