The RØDECaster Video will only accept 1080p signals – it does not have 4k support.
As long as your video device can output a 1920x1080 video feed, the RØDECaster Video will accept it – this covers the vast majority of 4K video sources.
The RØDECaster Video outputs up to 1080p60 video (for both recording and live streaming).
For more information about the RØDECaster Video, please see our RØDECaster Video User Guide.