04.08.2008 08:20 AM
Standards will help IPTV deliver the service level that customers expect

At 2008 NAB Show next week, Rich Chernock, chief technical officer of Triveni Digital, will discuss efforts in the IPTV industry to develop standards to assure that viewers receive the quality of service commonly expected by pay-TV subscribers.

Chernock will present “The Role of IPTV Standards in Achieving Quality of Service” April 16.

IPTV Update caught up with Chernock to get a preview of what he intends to discuss.

IPTV Update: You will be addressing the 2008 NAB Show to discuss IPTV, particularly the role of standards in assuring quality of service and an acceptable consumer experience. How would you assess where standards stand at this early stage of IPTV development and rollout?

Rich Chernock: I’d say in the IPTV world, the standards are pretty much at the early stages. IPTV is a relatively new technology as compared to digital terrestrial broadcast or digital cable. The standards there and recommended practices are much more mature.

ATIS has been doing some pretty good work on developing standards. They’ve defined many things, and there is more work to be done. But I think they can draw upon what has been learned in the other domains to get a pretty good jump start.

IPTV Update: How would you compare IPTV standards that are under development to DVB, ATSC and SCTE standards used for cable and terrestrial broadcast?

Richard Chernock: DVB has had recommended practices out for the longest amount of time. They did some very good work in producing ETR 101-290. ATSC was able to draw upon that, and add some more consideration, to produce A/78, which is a recommended practice for bitstream verification. DVB basically categorized a number of things that needed to be looked at in the digital transmission bit stream and added the notion of priority levels that certain types of errors are more important than other types of errors.

The work in ATSC added the notion of error severity — that everything isn’t black and white. There are certain errors that are not quite conformant to standards where viewers will never notice the difference, and there are other errors that are serious enough that you need to immediately get out of your chair and go fix it because nobody can watch your broadcast. SCTE built upon that and made it more appropriate in the cable world.

I believe the IPTV domain has the opportunity basically to pick and choose what’s been done in other domains, make it appropriate for their environment and come up with a very nice set of recommended practices or standards.

IPTV Update: Is that approach ATIS is taking?

Rich Chernock: I don’t know for sure because I’ve just recently gotten involved with the quality issues of IPTV at ATIS. But I have recommended that approach to some people there.

IPTV Update: Where do the efforts of ATIS task forces in developing IPTV standards stand in terms of designing metrics that can help IPTV operators assure QoS?

Rich Chernock: There have been a number of metric collections defined. What’s been completed so far is an overall framework, a set of metrics for linear broadcast — essentially scheduled television— and a set of metrics for public services. What they are currently working on is quality of experience models for linear broadcast, other metrics for broadcast advertising and video on demand.

So they are going very heavily down the metrics route, which is a good first step. You have to understand what kinds of things need to be looked at and where. The next step would be to figure out how to make some sense out of the metrics you’ve defined. One of the issues that arises in any of these monitoring systems is that the transport itself is so complex that it is almost guaranteed that something will be wrong at any time.

If one just lists the parameters that need to be measured and their possible bounds, you’d have information overload for the operators. When you have an environment where something is always wrong and the errors are constantly displayed, people tend not to see error signals. So going to the next step of categorizing and filtering, I think, would be an important thing.

IPTV Update: How would you assess IPTV operators have been getting along so far without these standards?

Rich Chernock: It’s been sort of ad hoc. There’s quite a variation in knowledge level out there. In many cases, we have people coming from the network domains and voice and data domains, and they are learning that video is a very different type of beast than voice and data. It has different characteristics, different things that are important. So they are basically in the learning stages to a large degree.

The big difference is that things that can impair video are very different from things that impair data and voice. Video has characteristics that a frame of data — or a picture — needs to be presented approximately every thirtieth of a second. If the data isn’t available at the time it needs to be presented, there’s no way to get it.

With data, you can always use a request to get more data sent to the path that’s been lost. In the case of video, if something is lost, it’s lost. There is no recovery from a loss, so a lot of the characteristics and things are important are quite a bit different from voice and data.

IPTV Update: Could you provide a little more insight into your presentation?

Rich Chernock: My presentation first off will give a view of where standards and recommended practices stand within ATIS, which is really one of the major standardization bodies for IPTV. I’ll provide an overview of their committees, how they operate, and a high-level overview of IPTV in general.

Then I’ll talk more about a practical view — what matters most to a customer and what needs to be done to ensure that the end product of the IPTV system actually provides the right quality.

What kinds of things need to be paid attention to first to determine that you do have a quality product, and second when problems exist, what you can do to isolate and localize them and figure out which equipment needs to be repaired.

I’m going to provide some insight on how you can get your arms around this thing and reduce the complexity of monitoring a complex setup into simple concepts that can be applied very easily.

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