Engineers in the midst of testing the distribution of digitally compressed broadcast signals advise post houses to caveat emptor if they’re thinking about investing in low-end equipment.

Right now, the post-production industry is on the periphery of the dvc standards testing pioneered by the international broadcasting and direct-to-home satellite service providers. But Carol Darling, chair of the Advanced Broadcasting Systems of Canada, says the post community should ‘exercise caution’ in purchasing new equipment which looks like a bargain, since it may ultimately undermine signal quality.

‘New equipment has to be tested knowing that new distribution channels will pass through two new links. The product will be posted, then pushed through a server, then sent through one or more distribution systems. With this number of processes, there’s a sense that if you degrade the signal at any point along the line, you affect the end result. Problems in your video input only get worse as you compress through the system,’ says Darling.

High-end equipment delivers a standard of product Darling calls ‘safe,’ but says at the low end, especially with the new non-linear edit suites and program servers, equipment should be pushed through comprehensive quality testing. ‘It’s important to have the quality in what comes out of the post process before you start feeding it through distribution systems.’

As part of its dvc testing processes, absoc is working on exactly how to test the effects of different compression rates and different kinds of compression on the quality of signal. ‘We haven’t yet blessed a test program to pursue tests specific to post-production, but there is a desire to look more closely at this area. They will have to go on in parallel with larger scale distribution tests since the reality is we’ll be living without a single standard for quite some time,’ says Darling.

The limited information available on how post-production standards fit into the new age of digital distribution through multiple-service providers is only part of the bigger picture of the direct-to-home satellite industry which is saddled with tech-related questions.

For the last several months, three direct-to-home satellite service providers have been knocking on broadcasters’ doors to lobby for their chosen dvc technology, all of which are different. ‘Chaos’ is an accurate descriptor for the direct-to-home satellite service industry that has marched ahead without a universal technical standard for dvc, says Don Braden, executive director of the Canadian Satellite Users Association.

It is a seemingly appropriate noun for the dth service providers themselves who are coping with delayed launches, lack of transponder space, and yet more government wrangling with a new round of crtc hearings beginning Oct. 30. But it’s perhaps a better word for the broadcasters who are caught in a kind of technical tug-of-war.

The crtc’s final call for dth applications last month yielded three major players venturing into the direct-to-home business in Canada: ExpressVu, owned by bce, WIC Western International Communications and Tee-Comm Electronics; Power DirecTv, the sister company of u.s-based DirecTv; and HomeStar, owned by a consortium of cable companies led by Shaw Communications.

ExpressVu’s tech of choice is TV/COM International; Power DirecTv, Thomson sa’s dds system used by its sister company DirecTv in the States; and HomeStar, General Instruments Digicipher. On the international scene, other major players include Scientific-Atlanta’s PowerVu system, used by much of the broadcasting industry in the u.s.

‘The manufacturers are trying to have their variations defined as the de facto standard in the marketplace, so you’ve got them linking up with dth providers to validate their technology. There’s that kind of marketing approach going on,’ says Braden.

According to Braden, not only is it not clear how adaptable each technology will be with an international standard once one is available, but the effects of multiple distribution streams on signal quality have yet to be established.

‘From the programmer’s point of view, the issue is: `If I’m going to send my signal through a number of different technologies, what happens to my signal at the end of the day?’ ‘ says Braden.

Matters are complicated further for Canadian broadcasters who are under considerable pressure from Telesat Canada to digitize quickly and clear space on its Anik E1 and Anik E2 satellites. Transponders are currently so packed that ExpressVu’s launch, once planned for September, is being held back until the eight units necessary to provide its service are available.

To date, about 20% of Canada’s broadcasters have converted to digital. By the end of the year, 70% to 80% of the broadcasters will have one or more of their signals digitized, says Paul Bush, director of the North American marketing and sales division for Telesat.

The 20% already beaming up digital consists largely of the new specialty services, which are under pressure both to access as many distribution systems as possible to increase ratings and to digitize their signals, which take one-quarter the space of analog transmissions, before having to pay Telesat full rental costs for transponder space. The specialties are paying $250,000 annual rent, about 25% of the regular fee until the end of the year, then 50% until April ’96 when they will pay 100%.

Some of the bigger broadcasters have put on the brakes, including the CTV Television Network and CanWest Global Communications, which are awaiting the results of further testing before making an investment.

To this end, the csua is beginning concatenation testing to pinpoint what happens to a digital signal which is processed through various digital processes and then compressed and distributed through what may be as many as three distribution systems.

‘There are all kinds of digital processes that happen to a program before it’s distributed. It goes through the editing and post-production processes, then into new server technologies. Broadcasters need to know what the limits of the technology are before they make long-term investments,’ says Darling.

Darling, who is vp engineering and operations at wtn by day, says the decision was made to go with Digicipher I, the preferred choice of the cable companies.

Some have been hesitant to go with Digicipher I because the decoder is guaranteed to be extinct when General Instruments comes out with Digicipher II technology and MPEG-2-compliant dvc standard, scheduled for release next March. But Darling says the short-term investment in a proven product that is used by the cable companies is worthwhile and is easily upgraded when the new product is available. ‘This is an interim solution only, but we have chosen a solution that will take us on an upgrade path.’

Darling says the decision to go with Digicipher was based in part on demand. ‘Everyone has different customers and my customers were expressing a preference for this technology.’

But she adds the digitized signal going out from wtn’s home base in Winnipeg is flawless. ‘I am really pleased. No resolution is lost in transferring to the cable head-ends. We’re getting a clean, crisp signal.’

Showcase is going with Digicipher II after having tested all three of the technologies selected by the Canadian distributors. The final decision was based on quality and with an eye to what will be a compatible system with other players when an open standard is mapped out, says Harvey Rogers, vp operations at Showcase.

Rogers was part of the ytv team when Digicipher I came on the market, adopted first by the Home Shopping Network, followed by ytv and then Vision tv. Having used Digicipher I, Rogers says he was comfortable with the quality of the signal and less so with the quality of compression on the competing systems. Given the time factor, the decision was made on what they felt was the best technology available right now, says Rogers. ‘One has to make decisions to clear transponder space.’

At Discovery Channel, all three systems continue to be evaluated and a choice will likely be made by the end of November. Discussions are continuing with the cable companies, and that’s a factor in making the decision as well as choosing a system which is available right away, says Ken Murphy, vp of production and administration at Discovery.

According to Murphy, each of the distributors has ‘a slightly different idea’ of what is available and affordable and in this race. A month of lead time for manufacturing or delivery will make all the difference, he says. ‘There’s a difference between a company to send its engineers up to a head-end in November versus driving through six-foot snowbanks a month later.’

Whatever technology the remaining broadcasters choose over the next three months, having three distributors using different technologies is building up to the question of who’s responsible for signal delivery, an issue the upcoming hearings will likely tackle.

In the final applications, service providers indicated that the financial responsibility of converting signals into three different streams should rest with the broadcasters. The cost of three decoders at $400,000 a piece is more than a million dollar investment, one the broadcasters are hesitant to make, to say the least.

‘No matter how many different service providers we have, we’ll provide the signal the same way we provide it to the cable operators. It is available from the main teleports, and what the distributors need to do to send it out is their business, providing quality standards are upheld,’ says Murphy.

While the crtc looks at the microcosmic issues, engineering and technical research groups in Canada and the u.s. are continuing research. For the past two years, absoc has been debating a common standard in sync with the Advanced Television Standards Committee and the Federal Communications Committee in the u.s., but the technology is new and a comprehensive plan is still being hammered out.

The Motion Picture Experts Group, an international consortium of engineers and technicians, has had the biggest influence to date on a digital transmission standard. What is available from the group so far, coined MPEG-2 technology, has been accepted by the industry as the international standard. But at this point, MPEG-2 is only a partial standard, lacking definitive standards for key components including service information tables and encryption and conditional access codes.

The idea behind MPEG-2 was to create an open standard for distribution technology. But since the equipment – including the hardware, DVB service information tables, Musicam and Dolby audio, and various approaches to encryption and conditional access technology – the u.s. industry is up and running, the battle is on for market share, and satellite service providers have forged ahead with manufacturing, creating the dog’s breakfast of technical standards on the market today.

The short-term tumult has left many feeling like all hope is lost for a common interoperable solution to implementing dvc. But according to Darling, the elements missing from the MPEG-2 standards may be ones that could facilitate an open system.

‘What is needed,’ she says, ‘are service information tables, really the recipe for how you find information in the systems. We may be able to duplicate or overlay the service information in the various distribution systems. All is not lost. We’re really in the early stages of product development.’