Although CEC is provided for the control of the HDMI devices, its implementation and operation is not that simple. It is common that HDMI sink users experience the HDMI source is not controllable through a single remote controller as expected, and vice versa. This is because many HDMI sources and sinks do not support CEC, including a few very well-known HDMI source devices and thus there is no simple way to control both the HDMI source and sink devices at once. There are also a number of HDMI devices supporting CEC, but require complicated steps to enable the feature in the equipment. Not as common are some devices that implement vendor-specific codes preventing HDMI source and sink devices from communicating.