A High Definition Multimedia Interface (HDMI) cable carries high speed encoded data, which are transmitted differentially over data channels, along with a clock. A Mobile High-Definition Link (MHL) cable carries high speed data which are multiplexed to achieve smaller connectors with fewer pins. A MHL-to-HDMI cable is proposed, which includes an embedded MHL to HDMI adapter device for demultiplexing the received MHL-formatted signal and outputting an HDMI-formatted signal. The embedded circuit is powered by a combination of power sources, the power being harvested from the high-speed HDMI signals themselves, including a startup circuit harvesting power from a low speed HDMI signal when power from the high-speed HDMI signals is not available.