Keeping It Pretty

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A picture is worth a thousand words, and these days, a clearer picture may be worth millions in subscriber revenue for cable operators.

With increased comparison to all-digital satellite competitors – and with DVDs and HDTV sets upping the clear-picture ante — the quality of cable's video picture has now come into sharper focus.

Cable operators and programmers face multiple challenges in making sure digital service delivers the video goods, particularly as they delve into premium-picture HDTV service.

Analog factor

Right from the start, cable operators face a more daunting task than their all-digital satellite foes, because much of their video spectrum is devoted to analog signals. So while customers may think all of the video they see via the digital set-top box is digital, the reality is that much of it is not.

Differences in resolution aside, analog signals don't have the built-in error-protection features of the newer digital technology, so they are far more prone to interference.

"If you look at the analog services, they have no such protection," said Paul Hearty, owner of technology assessment firm Technology Assessors Inc. and chairman of the Society of Cable & Telecommunications Engineer's digital-video subcommittee. "So anything that is floating around the plant and anything that is consequential to the analog transmission will show up in the signals."

Thanks to upgrades, plants have become more modern, which has helped alleviate the situation. But the ultimate solution is likely to reduce or eliminate the analog plant altogether.

"The cable operator's next step is in decreasing the analog and increasing the digital deliveries," Hearty said. "I don't think it would be economical for them to do further plant upgrades to improve analog performance, because they are probably pretty well close to peak."

Encoding tech

Indeed, going all-digital does make the cable picture clearer for video transmission, according to Bill Wall, Scientific-Atlanta Inc.'s technical director of subscriber networks.

"Digital is much more immune to issues with the plant or issues with the satellite link, so once you have got a reasonable level coming in, you are going to get very good pictures coming out, depending on how good the encoding was," he said. "And then you are really dependent on the encoding rather than the plant or anything else."

Video does depend on the original content, and it's a matter of garbage in, garbage out. If the original content contains errors, those mistakes will be magnified when the signal is processed through the encoder.

"To extent that we get content in that might be a little noisy or have other problems, we do use noise reduction in our transmission process to try to take out the noise and impairment that doesn't compress well and degrades the video. So we clean it up before we broadcast it," said Starz Encore Group LLC vice president of technology John Beyler. "We have a quality-control department that reviews all of the movies we get in.

"If they don't look good, and they don't meet our criteria we get another copy of them and try to only start out with only high-quality content, but we do do noise reduction before we transmit the movies to clean things up a little bit."

Encoding technology may also provide more help to programmers over time, Scientific-Atlanta's Wall said.

"I think we are continuing to see improvements in encoders, particularly in the pre-processing of the material that goes in to eliminate noise and try to get as clean of a picture as you can going into the encoder," he said.

The big squeeze

Hand-in-hand with encoding comes compression, or the amount the original video is squeezed for transmission during the encoding process.

While DVD, digital satellite and digital cable all use the same Moving Picture Experts Group-2 compression format for video, the cable operator's final decision on how much to compress material has an impact.

"I think the allocation of bandwidth by a distributor will be something that we discuss with our distributors more than we ever have before, because our customers are trying to successfully provide more and more services from them to the consumer in more and more little slices of bandwidth," said Bryan Burns, vice president of strategic business planning and development for ESPN Networks.

"Both sides of that situation, if you will — all the way to the consumer, I guess — clearly are being more mindful of how those bits and bytes are used, what they are used for and how they are used."

Sometimes those decisions produce less-than-ideal images, according to Hearty.

"There is no question that whether you are looking at the direct-to-home operator or the cable operator, there are cases where the pictures are too aggressively compressed," Hearty said. "Everybody knows that, and that's sort of a fact of life."

All in the picture

These issues have become more critical with the advent of HDTV, in which picture quality is the premium cablers are trying to sell. Thus far, when it comes to HD signals, the decision has been to err to the side of caution.

"I think the HD side of it is easy," said Cox Communications Inc. vice president of multimedia technology John Hildebrand. "We're looking at HD saying we're not going to do anything to degrade that picture at all. That's a digital picture that goes all the way to the set-top box, and you come out of the set-top box right into the HDTV."

That is also what the Comcast Media Center — which provides originates the signals of 97 video providers — has advised its network clients.

"What we see and what we've made recommendations to our clients is that they should not compromise on the HD signals," said CMC senior vice president and chief operating officer Gary Traver.

"What we're saying is, because of the issues regarding quality — because of the customer perception being raised from DVDs, and because of just the nature that HD is going to work — the real value is in starting out at high quality and maintaining that.

"And if you think that DBS is going to be bandwidth-constrained over the next couple of years, the best thing to do is to set the bar high and make them live up to what you've got."

That's especially true when it comes to statistical multiplexing, a common practice whereby two or more signals are fit onto the same 6-MHz channel.

Though stat muxing is a necessity for bandwidth conservation, in the HD world the balance might skew more toward less efficiency to maintain better video quality.

"Some of our customers have come back and said they want to shape or slice or combine, and we do have some concerns about that," Burns said. "The more slicing and dicing and shaping that is considered for our signal, the more we squirm a little bit, because in the HD world, when the consumer is buying this product more than ever before for picture clarity, if the signal is modified, then we get a little concerned about that.

Because ultimately the consumer experience will not be what he or she thought he or she was going to get, and the consumer will not be pleased with us or our distributors — and that's not good for either of us."

The consensus among today's HD players: Two is company, three is a crowd.

"With the standard MPEG-2 today, it's been our feedback that the best that you can do is running 2 HDs in a single 40-Megabit, 256 QAM channel," Traver said. "Putting three in that space is a little tough, particularly when you start talking about video material and not film material, and if some of the material contains sporting events."

Uniformly needed

As consumers become more aware of relative picture quality, it will also become more important to produce a consistent picture from network to network, said Broadcom Corp. vice president and chief scientist Rich Prodan.

"I think also maintaining uniformity is going to be pretty important, because if you get a direct feed from [Home Box Office] and they do a very good job, and then your local encoding is wanting, then people are going to see a difference," he said. "That's going to be a problem, too. We are going to have to have uniformity of the product."

In the end, picture-quality issues must be addressed as programmers and cable operators continue down the road to digital and HD.

"Look, we are all learning all together in this thing," Burns said. "This is not a negative thing, it's just that we are all learning how to do this."

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