There are distinct advantages to sending program enhancements using a digital broadcast (Transport B) instead of the Internet (Transport A). However, implementing Transport B is a challenging task. Today, there is no good way to get enhancement data from a network through a television station master control in synchronization with a program. There are three methods, with various drawbacks. The "embedded enhancements" method holds promise. SERVES Future ATVEF Transport B DTV Receivers METHOD 1 - BYPASS Unlike the commercial networks, PBS distributes both standard definition and HDTV programming via satellite to it's member stations in the ATSC format suitable for DTV broadcast. This allows stations to go on the air without initially purchasing a DTV MPEG encoding system. This also makes it possible for stations to carry enhanced television content delivered from PBS by simply connecting their satellite decoder to their transmitter input, "bypassing" any local encoding equipment. Severe limitations prevent this from being a long-term solution. INGREDIENTS - Satellite Decoder - DTV transmitter INSTRUCTIONS - Connect decoder to transmitter, either permanently, or just during enhanced programming. STATION DIAGRAM ADVANTAGES - Simple - Low Cost DISADVANTAGES - Stations must carry the channel package delivered by PBS, without any local customization. - Station logos, interstititals and FCC-required identification cannot be inserted. - The PSIP channel numbering will be 80 or 81 as inserted at PBS, no matter what the actual station channel. - DTV stations with encoders who are carried on digital cable will have their cable service disrupted if the PID structure of the MPEG stream is not identical between PBS and the local station. (Digital cable receivers do not use the PSIP information transmitted by stations.) METHOD 2 - STATION SYNCHRONIZATION It is conceptually possible to require every station broadcasting Transport B enhancements to install and operate data-insertion equipment identical to that being used today for the national feed. But the practical implications of this approach are daunting. (See Recipes:TV Dinners:ATVEF B for more detail.) INGREDIENTS - Complete DTV encoding/multiplexing/PSIP system. - ATSC/ATVEF-B Enhancement Data Server Triveni Digital - Skyscraper INSTRUCTIONS - Dynamically configure encoders and multiplexor to reserve bandwidth for a particular show's enhancements, ideally under traffic/automation control. - Load each show's enhancement content from the national producer into data server, in advance of each show, ideally under traffic/automation control. - Generate data enhancements at the proper time, ideally under automation control. - Repeat this procedure every time a show is aired, perhaps years into the future. STATION DIAGRAM ADVANTAGES - No change required in network or station video infrastructure. - Allows last minute changes to the enhancement content- long after the video editing is complete. - Also accommodates local enhancements. - Enhancements can be transmitted before the program or commercial actually begins. DISADVANTAGES - A complex system is required at all stations. - High implementation and operating cost would prevent adoption at many stations. - Potentially low reliability given many points of failure in various software systems. - Enhancements are not easily browsed by station and network personnel. METHOD 3 - EMBEDDED ENHANCEMENTS The majority of standard-definition serial digital video equipment has the ability to carry 300,000 bps of data within the vertical ancillary (VANC) data. HDTV serial digital equipment has even more capacity. Potentially, this data could be used to carry enhancement data throughout network and station infrastructures. INGREDIENTS - VANC Embedder (not yet available) at the producer. - SDI Equipment Supporting VANC (DVCPro, BetaCam SX, Pinnacle Servers, GVG Servers, etc.) - VANC De-Embedder (not yet available) just prior to each encoder input, at the station. - MPEG encoder with statistical multiplexing supporting enhancement data (not yet available). INSTRUCTIONS - Insert enhancement data at the national producer or network. - No action required at the station. STATION DIAGRAM ADVANTAGES - Simple station operation. Potentially totally automatic. - Low cost (presuming station SDI infrastructure is available.) - Potential for moderate cost browsing equipment for station viewing of enhancements. DISADVANTAGES - Data rate limited to 300,000 bps for standard definition. (This might be an advantage for transmission bandwidth management.) - Two simple but required devices are not yet available. Revised Tuesday, 07-Aug-2001 12:38:11 CDT - j © 2000 - 2003 Local Enhancement Collaborative & .