Multicasting—the transmission of multiple programs on the same DTV channel—is widely accepted and practiced in the United States. However, until last week that apparently was not the case in Mexico, where Group Salinas, which includes member company TV Azteca, received confirmation that the operation of its Hi-TV service is legal and legitimate.
Hi-TV is a free service consisting of multiple DTV channels, including general entertainment, movies, sports and children's programming. There is no charge for the service, which is available via over-the-air broadcast without contracts. According to an article in TV Latina, "Group decision supports COFETEL Salinas in Mexico", viewers must purchase equipment that will allow them to see the additional programming.
None of the articles I saw mentioned why special equipment was needed. I find it unlikely that existing DTV receivers in Mexico would not support multicast, as they are based on the ATSC standard. The only reason I can see a special receiver or other equipment would be needed would be if the programs were not being transmitted in MPEG-2 format. Using a more efficient compression technology such as AVC/H.264/MPEG-4 would make sense for a station group attempting to deliver many programs streams in limited bandwidth.
