Barb Roeder /
08.01.2005 12:00 PM
TV BROADCASTING ON THE INTERNET


TV stations are increasingly looking at the Internet as their second channel. Image created by Robin Metheny, art director.


Encoding

Technology for Internet delivery of audio and video channels has evolved, allowing broadcasters to create a full range of content 24/7 and cater to niche markets worldwide. In addition to the infrastructure needed for encoding and delivery, a large-scale effort to deliver content to a diverse audience will require automation, content management strategies and methods for tracking usage. The key is to cater to an audience that looks for personalization in all aspects of its viewing experience, including interactivity, viewer controls and the ability to schedule a convenient viewing time and location.

Most Internet television stations will offer their content in multiple formats and multiple bit rates to reach the widest audience. Today's delivery formats include Windows Media, Real, Flash Video, Quicktime and MPEG-4. In general, a format consists of its own set of codecs, a proprietary player and specialized server technology to achieve optimum delivery. Many computers support more than one format, but users often have their preferred player. PDAs and video phones are often designed around one format. Supporting multiple formats creates complexity in the production of Internet television channels, but automated encoding systems and application service providers with experience in delivery and management can ease the burden on a station's resources.



Figure 1. Signal acquisition, encoding and delivery system for an Internet television station. Click here to see an enlarged diagram.



The basic infrastructure for ingesting content for Internet delivery is shown in Figure 1. Signal conditioning should include color correction, time-base correction, noise reduction, and audio EQ and normalization. These will smooth out inconsistencies, making the encoding process easier. Your goal for input to the encoder should be to achieve the highest possibly quality, using signals routed via SDI or in a component analog format. DV is a possibility, though keep in mind that its limited color bandwidth may introduce artifacts in high-motion scenes, complex computer-generated graphics or blue-screening.

Encoding parameters will include frame size, frame rate and bit rate and often require some tradeoffs in terms of quality and efficiency for delivery. While it's possible to deliver television-quality signals, at least in the eyes of the viewer, it may not be practical or desirable. For many codecs, a full-screen video image (640 × 480) still requires between 700Kb/s and 1Mb/s to achieve decent quality. While this is possible in a large corporate environment, delivering this level of bandwidth will not be appreciated by the IT departments and may be blocked by firewall technology. In addition, consider the viewer at home or on the road who has access to DSL or a cable modem broadband network, which generally maxes out at 768Kb/s.

The broadband market is growing steadily, but network inconsistencies still necessitate a scaled approach. Streams that contain multiple bit rates, known as MBRs, can be encoded- in both Windows Media and Real. Therefore, a server can negotiate the best bit rate to deliver across any given network, as requested by the receiving client computer or device. Most MBR streams work most effectively if the bit rates are grouped for certain types of connections, for instance a 100Kb/s, 200Kb/s and 300Kb/s stream for broadband delivery or a 24Kb/s, 32Kb/s and 40Kb/s stream for dial-up and new wireless devices. Other formats offer only a static negotiation of bandwidth between server and client. Therefore, separate files need to be created for each bit rate, adding a good deal of complexity to the production and management of your content.

Because today's systems are capable of real-time encoding to multiple formats, you can deliver any programming destined for broadcast on the Internet as well. Unlike a broadcast, however, you can encode and store video-on-demand files so your audience can choose their own playlists.

Delivery

Always keep in mind the audience you want to reach. Some will have limited time and want their content in short clips. Others may be on mobile devices with limited viewing screens, so additional interactive elements are not as useful to them. In order to develop a cost-effective business model, interstitial advertising should be considered, but may need to be designed for specific markets and devices during production.



Each encoding workstation at X-Factor Communications has a mini audio mixer to fine tune audio before it goes to the encoders.
Once encoded, the streams must be pushed out to a delivery network. A broadcaster can maintain its own servers, or it can rely on a content distribution network (CDN) to reach the broadest audience in the most effective manner. Maintaining server farms is not for the faint of heart, but if your audience is small (below 1000 simultaneous viewers), it is possible to co-locate your own server at any ISP hosting center. Delivering 1000 streams is easily achievable using a dedicated media server for any format, but will also require up to 300Mb/s of constant network bandwidth, the equivalent of more than 20 T1 connections.

CDNs have the advantage of sophisticated technology for load balancing and edge caching, so the end user's viewing experience is more likely to be free of buffering and interruptions due to traffic congestion over the Internet. Many CDNs offer all of the common formats, but be aware of added costs for delivering any that might require proprietary servers.

On the viewer side, you can enhance the user's experience by customizing a Web interface that takes advantage of the content you want to deliver and offers viewers a different experience than just watching a television program. Customized player interfaces can be developed for any format. And by segmenting a browser page, other relevant materials can be offered to the viewer as well. For instance, links to related news stories and background material relevant to the content or advertising can be embedded alongside the video window.

Organizing

Managing such a large-scale operation will require some type of content publishing platform that can track all of the clips stored on your servers, metadata associated with those clips and any other relevant materials you are offering your viewers. Key words can be associated with any piece of content, whether it is a video or audio clip, images or text, so users can search for information to gain a better understanding of the message you are delivering. Coordinating this effort requires a hefty Web development team, or you can use applications that have been developed by vendors in the streaming media sector, including some CDN providers.

With the growing broadband market and the maturing technology for encoding and delivery, putting a television station on the Internet is viable now more than ever. Some of the production steps will come naturally to broadcasters and can be accomplished within the existing studio infrastructure. But some steps may be better left to outside vendors specializing in network delivery and complex Web development tools.




Barb Roeder is a consultant and president of BarbWired (www.barb-wired.net. ).



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