BSkyB's standard definition broadcasts are in DVB-compliant MPEG-2, with the Sky Movies and Sky Box Office channels including optional Dolby Digital soundtracks for recent films, although these are only accessible with a Sky+ box. Sky+ HD material is broadcast using MPEG-4 and most of the HD material uses the DVB-S2 standard. Interactive services and 7-day EPG use the proprietary OpenTV system, with set-top boxes including modems for a return path. Sky News, amongst other channels, provides a pseudo-video on demand interactive service by broadcasting looping video streams.
What are BSkyB's standard definition broadcasts compliant with? Sky Movies and Sky Box office also include what optional soundtracks? What is Sky+ HD material broadcast using? What is the proprietary system that Sky+HD uses? What does most of the HD material use as a standard?