These new DIRECTV HD channels required an H20/HR20 or later model set top box  (STB) capable of supporting the  MPEG-4  standard for HD programming. These models also introduced HDMI support for HDTVs with an HDMI port.
The expansion of DIRECTV's HD offerings necessitated a set-top box that could decode high-definition content using the MPEG-4 standard, and also supported the latest digital audio technologies through HDMI connectivity.