BUILDING HD FACILITIES

How to build an HD broadcast facility
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At the BBC Broadcast Centre in London, TSL installed a dedicated HD playout system for Red Bee.

The arrival of HDTV is the most significant revolution to hit the broadcast industry since the change from black-and-white to color pictures. This transition in picture quality affects the whole broadcast chain, as well as every network worldwide, changing the viewing experience of many television genres for good.

Last year, analyst Screen Digest predicted that by 2010, 100 HD channels would be available in Europe with more than 11 million households equipped to watch television in HD. The analyst also reported that on a global basis, by the end of 2010, the number of HD-ready households would reach 174 million or 22 percent of TV households. The figure translates to 59 percent in the United States, 66 percent in Japan and 30 percent in western Europe.

With this in mind, it may seem an obvious choice for broadcasters to jump on the HD train now. However, before the station accountant will even consider loosening his grip on the purse strings, a broadcaster must understand the answers to many questions, including:

  • What implications does HD have for the average broadcaster?
  • Is the technology readily available?
  • What are the technical challenges?
  • Does the cost warrant making the transition now?
  • Does geography play a part?

HD-ready is a phrase that has recently become commonplace at broadcast trade shows. In broad terms, this means products and infrastructure that are essentially SD, with HD capabilities built-in.

Few stations are upgrading from SDI to full HD. Instead, most are building hybrid facilities where the cabling, routing and infrastructure are HD-capable even if the acquisition or transmission output is not. When building a hybrid facility, broadcasters need to take into account several factors across the broadcast chain to ensure a smooth migration at a later date when market or financial trends dictate.

Monitoring and QC

A broadcaster's smooth, day-to-day operation relies on monitoring and quality control. When making the transition to HD, it is important for broadcasters to have a dual-standard monitoring system that can upscale SD pictures.

Broadcasters need to ensure that they can monitor the technical artifacts for both SD and HD, which can add extra costs to some of the equipment. Most manufacturers now include identified options to monitor SD and HD.

Video servers

These require playout ports that are agile, meaning they can play out both SD and HD material. Broadcasters must take into account that there are some specific automation and video server combinations that don't handle certain types of HD. Therefore, when they switch to HD, there may be progressive and interlaced material, which affects the way the automation system counts frames.

Capture and storage

One of the hardest tasks in the HD domain involves capturing video and storing it cleanly, and it is an area of diminishing return. A broadcaster can spend a lot of money on only a small improvement because the material has to be compressed at a much higher speed. The compression has to be significantly better, so broadcasters have a harder job in a shorter time frame.

File-based storage

A major factor in the HD revolution is file-based storage, and it brings about a new set of challenges for server manufacturers. The larger size of uncompressed HD, 2K and 4K files brings fresh challenges of how to store cost-effectively. Costs have, however, continued to fall as the technology development rate has increased. An SD storage system for 1000 hours of material 10 years ago cost the same as an HD system for 1000 hours does today.

Broadcasters also have to decide on other factors, such as how many mezzanine levels they keep and whether they should compress down to Avid DN×HD or Panasonic DVCPRO HD interims and then compresses further for transmission. This means that they might end up keeping at least three copies.

Physical size

File size isn't the only problem when considering storage; physical size is also a factor. Before HD, systems would easily fit into a rack. However, the latest HD servers and appliances are often based on the next-generation 1RU generic IT servers, which are more than 1m deep. This makes them difficult to physically handle, mount and cable into the rack.

Environmental issues of higher power consumption in a smaller space mean more powerful air-conditioning to deal with the extra heating. These IT servers also produce a high level of ambient noise.

Installation

During the systems integration of an HD system, broadcasters must pay attention to the actual physical installation itself and be aware that HD is less resilient to poorly connected cables. Equally, the dressing of and bends in cables needs to be more carefully monitored to ensure that there is no loss of signal, which can be caused by the higher frequencies involved in HD.

Cost implications

Two or three years ago, HD products could be four times the cost of equivalent SD ones. Typically, these related to items where the SD had high production and the HD replacement was noticeably more limited.

Nowadays, manufacturers have recognized that there is little point in making two versions. As a result, the manufacturing costs for some HD products are not significantly greater. Manufacturers have embraced HD as the way to go, which has driven the manufacturing costs down. Manufacturers have also designed the products to be heavily software-based. For example, many routing systems are now agnostic and accept SD or HD.

Cameras and VTRs hold a significant premium because they have to do a much better job in the HD format. With camera optics, broadcasters hit diminishing returns because they are striving for a high level of quality. Monitoring can also be quite expensive for full HD, but most monitoring now is downscaled and shared across a multiviewer so the difference in cost is negligible.

Geography

Two decades ago, following the political changes in Central and Eastern Europe, countries with traditionally only a national broadcaster saw their markets open up, and private TV stations began to appear. At that time, funds were limited, and most of these new broadcasters opted for the cost-effective technology at that time: analog PAL.

Now, the technology needs to be replaced. SDI is available, but it is getting toward the end of its life, making HD the next step. Therefore, many of these broadcasters are missing a whole generation of technology by going straight to HD.

Romania's ProTV is a good example. The network upgraded from an analog system to an HD channel. Similarly, there are parts of the Middle East where private stations are coming straight in with HD offerings.

For these new broadcasters, it would be surprising if they chose not to build in HD, as they can often launch their service via satellite. This reduces transmission costs to the home compared to traditional terrestrial methods. However, there still has to be a good economic model in place, as well as quality reasons, when making the transition to HD.

Several years ago, when the rest of the world went digital multichannel, Australia decided not to because its five main broadcasters wanted to retain the monopoly. Instead, the government put pressure on those broadcasters to invest in HD, and they went straight from analog to HD.

This was at a point when HD equipment cost 10 times more than it does today, and there were no HD receivers available. The Australian manufacturers produced some HD receivers with a significant price tag, which made them unattainable to average Australian viewers. Because of this and other economic reasons, the broadcasters were forced to produce only SD programs, putting them through an upconverter and transmitting them as HD.

Despite the many new stations launching in HD, there are still plenty of new SD channels being added on satellite, cable and DTT using serial digital and 16:9. SDTV pictures are still perfectly acceptable, though there are certain genres where HD stands out.

In the United States, for example, Time Warner installed 1000 HD set-top boxes in North Carolina for the 2007 Super Bowl. U.S. consumer electronics retailer Circuit City conducted a survey that found that 48 percent of U.S. citizens would prefer to watch the Super Bowl on an HDTV, compared with 26 percent who would rather attend the Super Bowl and cheer from the stands.

Adding audio to the mix

Other than picture quality, what does HD offer? For the consumer, the acquisition of an HD system often warrants an improved audio system, such as Dolby Digital 5.1 surround. Adding this enhanced audio infrastructure brings another level of complexity in the systems integration for HD, and not all broadcasters have solved the pitfalls that exist.

In an HD application, broadcasters carry the original sound plus 5.1 surround, usually on a second AES signal using Dolby E. Additional processing can noticeably increase the costs of the system, specifically around a presentation mixer where the picture may require compensating frame delays to enable the decoding and recoding of Dolby E to retain lip sync. However, this still doesn't always prevent the perennial issue of lip sync errors occurring at the end of the transmission chain.

Constant and careful monitoring of multichannel audio is required. This presents practical challenges in control room designs that usually focus on monitoring multiple sources of video, with stereo audio only.

More challenges for HD

Broadcasters' production requirements have changed, and bandwidth is now a consideration. Most broadcasters want more channels, and squeezing an HD picture in the given space while maintaining the picture quality is not easy. If a broadcaster has HD with digital surround sound, the last thing it wants to do is compromise that quality. Consumers that have paid an enhanced subscription for their HD service don't want to be shortchanged because too many channels have been added, resulting in picture quality similar to SD.

Many European countries that have had television for a long time, such as the UK, simply don't have enough space on the terrestrial spectrum to easily squeeze in HD signals. This will require the authorities to free up more bandwidth. The only other way to do this quickly and relatively cheaply is by satellite. As a result, countries with a satellite distribution system will find it easier and cheaper to transition to HD.

As mentioned before, in many Central and Eastern European countries, the regulations are now more relaxed. This allows more private broadcasters in, so there is more spectrum space. As a result, there is a business model for these new broadcasters to launch pay-per-view- or subscription-based services via satellite.

The driving force: consumers

The main push for HD — other than the availability of technology — is large-screen displays and the viewer experience that comes with both sports and movies. TV viewing of fast-action sports is already vastly improved by HD and will continue to be as the production techniques for each sport develop.

The market is highly competitive, with handheld devices and the Internet challenging broadcasters. The arrival of HD DVD will up the stakes further. Like black-and-white television, SD will one day be a thing of nostalgia, as HD becomes the standard.

David Phillips is CEO of TSL.