The high-definition multimedia interface (HDMI) standard is the leading standard for the transmission of uncompressed video data within the home. Because of the technology used for HDMI and the associated high data rates, compliance tests require complex and cost-intensive T&M equipment. This paper describes an efficient alternative in the form of a sampling oscilloscope. It covers the fundamental principle behind electrical testing of HDMI sources such as those found in set-top boxes, Blue-ray players, cameras, PCs and smartphones. It additionally discusses the differences as compared to the conventional time-domain analysis methods.