About AT&T U-verse
U-verse TV is delivered via IPTV from the head-end to the consumer's Total Home DVR or standard set-top box. U-verse uses H.264 (MPEG-4 AVC) encoding which compresses video more efficiently than the traditional MPEG-2 codec. Broadcast channels are distributed via IP multicast, allowing a single stream (channel) to be sent to any number of recipients. The system is also designed for individual unicasts for video on demand, central time shifting, start-over services and other programs desired by only one home at that particular time. The set-top box does not have a conventional tuner, but is an IP multicast client which requests the stream desired. In the IP multicast model, only the streams the customer uses are sent. The customer's connection need not have the capacity to carry all available channels simultaneously.