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10.10.2006
Originally featured on BroadcastEngineering.com
Verification and compliance testing are critical to IPTV success

Last month at IBC2006 in Amsterdam, Pixelmetrix unveiled an IPTV test stream generator to assist in the process of evaluation, compliance testing and verification of networks, monitoring and equipment analysis.

Dubbed the DVStorIP-Gen, the product allows broadcasters using IPTV delivery to verify that a specific transmission actually occurred.

IPTV Update caught up with company president and CEO Danny Wilson after the convention to discuss the role and importance of IPTV transmission verification.

IPTV Update: IPTV is a new, emerging distribution avenue for content providers like broadcasters. As IPTV subscriptions grow, how important will it be for broadcasters to automate verification that content is actually delivered? What are some of the challenges of acquiring and maintaining a verification record?

Danny Wilson: IPTV really has the same three parts as cable, satellite and terrestrial TV delivery platforms: a headend to acquire and package content, a transport network and final delivery. In the case of IPTV, the final delivery is IP protocol, usually over xDSL or fiber.

So far, IPTV operators have been overly focused on the mechanics of the IP network. Why not? With their data background, they are familiar and comfortable with the technology, so they focus in their comfort zone. This has been at the expense of adequate attention to the first part of the system: the headend to acquire and package the content.

So, the challenge for effective monitoring for IPTV operators is to observe the full length of the transmission chain: from content acquisition, departure from the headend, to a point of observation as close to the viewer as possible. The last point will most practically be at the DSLAM.

Content providers, or “broadcasters” as you suggest in your question, all have the same question: Is their content being delivered appropriately over each of the different delivery mechanisms? The burden of proof could fall upon the content provider himself, or on the transmission operator as part of their Service Level Agreement obligations.

For a content provider to validate that content is properly delivered to an end point — whether cable or IPTV — the most effective way is to actually subscribe to the service. End-point monitoring devices can be affixed to those end points, and the content providers themselves can make judgment upon the level of quality.

If the obligation falls on the transmission operator, the same end-point monitoring equipment can be deployed, except that the transmission operator usually then has to create monthly service quality reports to the content provider.

IPTVU: Verifying terrestrial transmission is relatively simple. But doesn’t the fact that an IPTV system delivers content to specific IP addresses — potentially at any time of the day or night for a given program to each individual subscriber via VOD — make such verification monitoring difficult? How can that be accommodated?

DW: Actually, even today, the majority of content is “broadcast,” meaning the same content is delivered to every subscriber. Broadcast content delivery within an IPTV network employs the multicast capability of IP networks. When a set-top box “tunes” into a specific channel, it sends a JOIN request into the network. From there, each router in the network forwards only that traffic to the set-top box.

The most significant difference between IPTV and terrestrial broadcasting is that in terrestrial, all the “channels” are broadcast over the airwaves simultaneously. However, because the DSL network has limited bandwidth in the last mile, only one or two “channels” can be received at the STB at one time. This means the “tuning” is done in the network for IPTV as opposed to tuning directly in the STB or television set.

But despite that, the closer you can monitor to the end subscriber, the more accurate your measurement. Just as off-air monitoring of terrestrial networks can only allow you to deduce viewer perception, monitoring IPTV networks at the DSLAM level provides the same.

VOD validation is a more difficult issue. Each viewer can request a different program as well as have the ability to start, stop and fast-forward the video content. IPTV networks implement VOD over dedicated point-to-point unicast IP flows. Having many such unicast flows on an IP network increases overall network traffic because there is no common resource usage.

Again, monitoring VOD performance for all subscribers is a daunting task. Alternatively, an audit device at the DSLAM level can assist in evaluating VOD performance by scanning through available programs while measuring quality of experience parameters, such as channel change and/or video quality.

IPTVU: Could you discuss the importance of compliance testing and verification to the ultimate success of IPTV?

DW: In the early days of any technology deployment, lack of established standards limits interoperability of systems between different vendors. Such incompatibilities have been worked out in digital television through a standard toolkit of standards, such as ASI, MPEG-2 and so forth.

IPTV today also draws upon many established standards from the worlds of Internet, television and IT. However, it is collecting them together in a working set that causes problems.

IP networks are not designed for continuous delivery of real-time data. They are packet switched, and “your data” is mixed with other traffic. This could result in tremendous jitter in the network or perhaps data being discarded altogether. So, how to adequately dimension network capacity to avoid these problems is yet to be fully understood.

Contrast this with the decades of experience the phone industry has in “traffic engineering.” It has developed extensive statistical models to predict required network capacity, knowing that everyone will call home to mom on Christmas day.

So, while there are many standards, getting it all working together is a challenge. That is where adequate compliance and verification testing prior to deployment will help catch problems reducing the risk of expensive field upgrades.

IPTVU: How does the new DVStorIP-Gen address the need for compliance testing and verification of networks?

DW: DVStorIP-Gen can generate multiple video streams from its internal hard disk and replicate those video streams to hundreds of IP destinations. Furthermore, the product can introduce various errors and impairments into the IP flow, allowing you to understand how robust your service is when the network degrades.

Testing like this is difficult in real network situations. Even if you have access to a large headend of video sources, it is difficult — if not impossible — to introduce specific impairments into an operating IP network in a controlled manner.

In that way, DVStorIP-Gen provides an essential building block in a “captive network” — a safe environment to evaluate new equipment or trial various network technologies without risking your live broadcasts.

IPTVU: Is there anything else you would like to add?

DW: In many ways, IPTV is the same but different. The components of an IPTV network — content acquisition, packaging, transmission and delivery — are the same as cable and satellite platforms. The first part of that delivery chain is well understood by the broadcast industry, while the latter part of the chain is well understood by the telecom industry. Melding the two technologies, cultures and vocabularies together to create a profitable business is the real challenge!

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