Datacasting At WRAL - TvTechnology

Datacasting At WRAL

Technological changes are perceived in many quarters of the broadcast industry much the same way that the change in current flow is perceived in an inductor--with marked opposition.
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Technological changes are perceived in many quarters of the broadcast industry much the same way that the change in current flow is perceived in an inductor÷with marked opposition. The advent of digital television has had its share of resistance, despite the fact that many of the enhancements it brings with it could help raise the bottom line of most any station's bank account and deliver some rather nice dividends to its investors. In stark contrast, this resistance to the unfamiliar is nearly non-existent at WRAL-TV/DT in Raleigh, NC. As Capitol Broadcasting's flagship station, it has led the way in implementing cutting-edge digital technology in its plant. One example of this is the station's development of datacasting capabilities. Under the direction of Sam Matheny, vice president and general manager of DTVPlus (a subsidiary of Capitol Broadcasting) Capitol Broadcasting has built an operational datacasting facility it calls "TotalCast," which is broadcast via WRAL-DT. Following WRAL's lead and assembling the same bits and pieces, nearly any DTV station can also deploy datacasting, in addition to its regular television programming, be it HD, SD, or even multicasting. Currently, TotalCast includes video-on-demand (VOD) from WRAL-TV/DT news, a custom news "microsite" from WRAL.com, computer games, short films, software, and other local programming. Received content may be stored on an end user's computer hard disk, where it is available for nearly instant access. WRAL-DT isn't in datacasting for the fun of it; it expects to get a very healthy return on its investment over the next few years as the business model settles into place.



The steps to implementing datacasting are fairly straight-forward. First, you need digital content that is desirable to consumers. This can be your station's locally produced programming streamed out on a server. Care must be taken to ensure that whatever you make available is free of copyright issues or has been cleared for this kind of distribution. This, or other servers, can be used to distribute movies, educational material, or other types of information that can be revenue-producing either on a subscription or per-view basis. In addition to a VOD server, WRAL-DT makes its Web server, Internet sources, and what it calls Client "X" Content÷sort of a catch-all for digital material not covered in the VOD, Web or Internet sources÷available.

According to Matheny, the WRAL.com microsite and VOD products are wonderful extensions of the WRAL brand. "This is our core product and enables us to better serve our markets by providing access to on-demand news and information through our digital signal. It is a constantly updated broadband wireless cache."

Looking toward the future, Matheny added, "The short films and games are a good way for us to build subscription or PPV services, while our tools channel is a software distribution model." He concluded, "Right now these are really focused on introducing people to the idea that DTV can deliver such services."

An important aspect of any datacasting system expected to generate revenue is control. Content Control Administration (CCA) is exceedingly important and is the repository for any subscriber list and its subscriber management system (SMS). It is also where the system keeps track and grants permission or Conditional Access (CA), to access the various types of material that will be offered on the system and generates the information that keeps track of who gets billed for what. With the rampant paranoia over copyright protection and intellectual property rights issues, this level of control is absolutely essential. Although SMS and CA are not currently in use at WRAL-DT, they will no doubt be activated once all the systems are tried, tested, and ready for those kinds of services.

All digital source material and the CA are combined or multiplexed together in the Modular Content Producer (MCP). The output of the MCP is sent to a Triveni Digital Data Hub bandwidth allocation and content encoding device. The Triveni Digital platform arranges the incoming bit stream into its most efficient format.

There are three types of bit rates. Simply put, variable bit rate (VBR) sends the material out using whatever bandwidth is required, at any given moment. Constant bit rate (CBR) keeps the amount of data constant by stuffing blank bits to fill-in when there is not enough from the originating source, thereby keeping the required bandwidth constant. Statistical multiplexing incorporates the best of both VBR and CBR by re-arranging the bits so they are sent out as a constant stream, holding excessive bits over a pre-determined level to fill in when there is less, thereby maintaining a constant level and bandwidth.

The output of the Triveni Digital platform is in an Internet Protocol (IP) format. This IP stream is then fed into the Thales Broadcast & Multimedia Opal IP Encapsulator. The Encapsulator serves as a gateway where the IP format is encapsulated into an MPEG-2 stream so that it is compatible with the other parts of the broadcast stream. Once the DTVPlus MPEG-2 bit stream is in a fixed bandwidth configuration and has gone through the Opal IP Encapsulator, it is ready to be combined with the remainder of WRAL-DT's bit stream (audio, video, PSIP, etc.), which is done in a DiviCom multiplexer. The output of the DiviCom multiplexer is the 19.4 Mbps that is fed to the WRAL-DT digital transmitter.

It is anyone's guess when DTV sets will include a computer-like device that will accommodate the functions of the PCI card that is a required part of the gear necessary to receive the datacasting portion of WRAL-DT's signal. In the interim, it is necessary to have a proprietary accessDTV PCI card to avail oneself of these special datacasting services.

Not just any computer will work; it must be a Pentium II (or higher) desktop PC with a VGA monitor. AccessDTV says that these kinds of monitors have the capability of being DTV-ready and HDTV-ready display devices. Despite the fact that TV viewing on PCs has never really taken off, the company believes that because of the greater than 65 percent penetration in U.S. homes with over fifty million Pentium II or later model PCs, there is a good chance for acceptance.

The PCI card has both a VHF and UHF F-type connector for over-the-air (RF) reception. Presumably this would work with a cable input, were it available. With all the concerns over 8-VSB reception, it is important to note that the PCI card has the latest generation NxtWave chip, which addresses multipath issues, followed by a TeraLogic demuxer.

In addition to the direct hardwire output to the computer where the PCI card is installed, there are also three other connectors, an RCA phonojack, an S-video jack, and a D-9 connector. These outputs deliver baseband video (digital SD/HD) as well as offering several audio options; AC3 (Dolby 5.1 channels of audio) or a stereo output. The DTV pictures and sound can be viewed and listened to on both the computer and on a DTV monitor.

Since TotalCast was launched less than six months ago, there is still no established track record that can be referred to that shows it as either a smashing success or failure. Being slow out of the gate, however, doesn't necessarily mean it won't end up a winner. Only time will tell, and if or once the public accepts the marriage of computers and digital television÷who knows÷maybe we'll be calling Matheny the Columbus of datacasting.