by Peter J. Brown

Rapid changes are transforming the broadcast world. Caching; pull or on-demand services; automation; new displays and graphical user interfaces (GUIs) are having an impact on every link in the chain. the explosive growth in the demand for new Internet Protocol (IP)-based applications and content looms large as well.

The greater emphasis on encoder efficiency and performance is unmistakable. Digital encoding and video compression technologies are defining and having an impact on all the activities that go on around them, both upstream and downstream. The entire digital world may not be where it is today because of encoders alone, but all you have to do is pull the plug on one encoder and watch as the whole thing falls apart.

“Broadcasters and service providers in general have not even begun to see the complexity that they will see in five years. We have just begun, for example, to gauge the impact of what systems intelligence is bringing to the realm of encoding,” says John DeLay, director of DTV studio products in the broadcast communications division of Harris Corp. in Mason, OH.

Barry Hobbs, director of engineering and field support at Tandberg Television Inc. in Newport Beach, CA, highlights a few fundamental changes that are taking place with respect to the encoding platforms themselves.

“We have much more powerful chips to work with thanks to very large-scale integration (VLSI), and this has resulted in better motion estimation and much lower bit rate yields. With MPEG 2 encoder chips, which are much better, so too are both our own implementations and third-party implementations,” Hobbs says. “Whereas SDTV might require 8 Mbps today, a year from now pure efficiency gains will reduce that figure to 6.4 Mbps to 7.2 Mbps. This follows the trend of a 10 to 20 percent increase in encoding efficiency each year.”

Improvements or gains in encoding and video compression cannot be viewed in a vacuum. They must be seen as part of the overall network fabric, along with such things as modulation and multiplexing.

“The 8-PSK modulators are ready to go,” Hobbs says. “Tandberg has 16 QAM modulators in development, and testing of the 16 QAM modulation scheme has been scheduled with Eutelsat, to mention just one satellite operator that has 16 QAM in development. Of course, there are antenna gain and power issues, with operators always wanting to have more fade margin on hand with Ku-band.”

Hobbs indicates that a general rule is that 16 QAM will require 7- to 10-meter antennas. And with any switching of modulation, there is a corresponding swap out of receivers. Add it all up and you can see why Hobbs stresses that 16 QAM and 8-PSK is not for the weak at heart.

Encoders are software-driven machines, and the software today is incredible.

“We’re getting smarter about dealing with motion estimation in MPEG 2 and such things as scene change detection, where a complete change in signal information used to be mistaken for motion, along with special events such as fade to black,” says Marty Stein, senior marketing director at Motorola Broadband Communications Sector in San Diego (formerly General Instrument Corp.), which produces the Digicipher 2 line of encoders. “The emphasis today in terms of motion estimation is on enabling the encoder to look ahead 5 to 10 frames. This increases the bandwidth efficiency considerably. This is not to be confused with forward error correction (FEC), which protects the integrity of the already compressed stream.”

The DBS sector has its own set of requirements, and Milpitas, CA-based Divicom Inc. provides encoders to a number of DBS companies including DirecTV Inc., Echostar Communications Corp. and Expressvu Inc. in Canada. In early 2000, Harmonic Inc. in Sunnyvale, CA, is scheduled to complete its acquisition of Divicom.

“For the DBS market, it still comes down to video compression efficiency, and getting the most channels into the transponder as possible. Providing the ultimate video quality to the videophile is not the objective here. It is to deliver to the consumer the most service options possible, while maintaining an acceptable, consumer-level video quality,” says Matthew Goldman, Divicom’s director of engineering for advanced systems development.

Where Is The Digital Version Of Atis?

Mel Olinsky, executive director of affiliate services for CBS Newspath in New York City, indicates that Holon, Israel-based Tadiran Scopus Ltd.’s Codico E-1100 encoders and Codico IRD-2520s enable CBS Newspath to distribute content at 7.14 Mbps using 4:2:0 DVB compression. A high-speed file transfer beta test is underway now. In July 2000, Olinsky says CBS Newspath hopes to begin using a Scopus MCPC system for convention coverage. Olinsky adds that the 4:2:0 requires fewer overheads than 4:2:2 at 7 Mbps, and that this set- up is working fine.

On the digital satellite news gathering side, CBS Newspath has turned to San Diego-based Tiernan Communications’ TE-300s for a remarkably flexible SCPC-based contribution solution. The service is so affordable that affiliates are rolling out small digital trucks and even secondary DSNG vehicles. In addition, the time-consuming and expensive process of ordering turnarounds, which was a common practice for affiliates on C-band, has been eliminated as well, according to Olinsky.

“The price of a satellite feed for a five-minute live shot is under $25 today. We elect to do SCPC from multiple locations. Everyone is configured for MCPC, which will allow us to put up 15 channels on a carrier rather than eight. Going to MCPC is the next step,” Olinsky says. “At this time, for special event situations such as our recent election coverage in Iowa, we daisy chain the Tiernan encoders together at the remote site to create a kind of poor man’s MCPC.”

One of Olinsky’s biggest complaints about the steady migration to a digital Ku-band environment is the mysterious way in which the old reliable analog automated transponder identification system (ATIS) has suddenly vanished.

“They are able to pack so much information into the datastream, I do not know why they cannot slip in a code or digital tag which will allow us, back in the network operations center, to easily identify the digital carrier we are looking at. Manufacturers need to realize that from a transport management standpoint, this is more than a mere inconvenience for those of us who have to sort through dozens of digital feeds simultaneously,” Olinsky says.

CBS Newspath now has direct Ku-band access from the rooftop of its building in downtown Manhattan to Telstar 6 and GE 5. According to Olinsky, the old C-band satellite distribution network ceased operating last July 1. Previously, CBS Newspath put its outbound signals on a fiber feed to the Group W uplink facility in Stamford, CT.

“They live very well together. Because of all of the terrestrial interference here in New York, we could not uplink from this site previously using C-band. Now, we have installed a complete encoding solution from Tadiran Scopus. Miralite Communications was the systems integrator. With this new system, we are now able to reach all of our 200 affiliates here in the United States, as well as subscribers in Mexico, Central America and Canada right from our rooftop,” Olinsky says. “There are numerous advantages, including the fact that we can control the feed ourselves.”

Olinsky indicates that CBS Newspath could run as many as 15 channels on a single carrier per transponder, and that there are no problems to report with 54 MHz transponders split evenly between analog and digital Ku-band services. He has been somewhat surprised by how robust these digital carriers really are. However, transponder management issues are still a top priority for Olinsky, hence the ATIS-related concerns. He wants to see a more flexible, automated solution emerge to better manage, monitor and control the numerous digital feeds on a single transponder.

HDTV: The Next Step

HDTV encoders like Divicom’s Mediaview MV400, the Digicipher 2 HD and Tiernan Communications’ THE-1 are becoming increasingly popular as HDTV gradually begins to gain momentum. Still, there are no signs that HDTV is going through an explosive growth phase, not yet anyway. John J. Turner, president of Turner Engineering Inc. in Mountain Lakes, NJ, has assembled an ATM lab for HDTV testing purposes.

Turner Engineering’s HDTV credentials include broadcasting a Panasonic-sponsored jazz festival, live from Washington Square in New York last fall. This was a tricky simulcast that required an NTSC downconversion of the HDTV signal, so that it could be beamed over to the site where the IP streaming or Webcast version of the concert originated.

“I used a 54 MHz transponder on GE 5. Using QPSK, I placed the feed for the ATSC HD data on one side, and the analog NTSC on the other side to avoid mutual interference as well as protect GE customers on the adjacent transponders from any intermodulation distortion,” says Turner.

When asked to identify his favorite choice in the HD encoder category, Turner picks the Videostar HD Encoder from Lucent Digital Video.

“This encoder has exceptional flexibility with both hardware interfaces and operational features. Close behind it are Divicom and GI. These three units also provide the best video quality,” Turner says. “We are very impressed with the Sencore ATSC/DVB products for their user friendliness. Their real-time transport analyzer is designed for today’s NOC. Their stream station is used by PBS, for example. It offers a comprehensive set of software tools useful for stream management and studio file manipulation.”

Turner indicates that ATSC audio/video synch is a non-issue, and results from operator error. “There are plenty of experienced operators around, and plenty of adequate test and measurement tools around, too. So whenever you hear about HDTV-related problems, the first thing you look for is inexperienced operators, or a lack of adequate tools, or both,” Turner says.

He also believes the while an ATSC CBR transport stream “fits neatly into a 27/36/54 MHz satellite transponder spectrum plan,” there are contribution performance and interoperability problems which do not fit so neatly.

“Encoding to a nominal 45 Mbps transport stream provides better contribution performance and interoperability with terrestrial T3 TDM and ATM circuits, but this would require an entire 36 MHz transponder, assuming reasonable receiver dish size,” Turner says.

He is referring to the common practice of using a terrestrial backhaul for HDTV signals at a bit rate of 44.76 Mbps (DS-3). This is a contribution option that many sports programming providers in particular are exploring for their HDTV broadcasts. Perhaps the best-known example is ABC’s Monday Night Football, which began HDTV broadcasts during the last NFL season. ABC is using Tiernan Communications’ THE-1 HDTV encoders, along with TDR-6 decoders, and the TUI-10 protocol converters.

“In large part, the DS-3 option for contribution links for HDTV sports telecasts has been used because this is the predominate existing terrestrial transport infrastructure that exists for high-quality contribution of video/audio service,” says Richard Wolf, New York-based ABC Inc.’s vice president for telecommunications and distribution services for ABC broadcast and operations. “From a technical perspective, higher bandwidth channels are desired; however, existing telecommunications and broadcast plant infrastructure, and present transport cost models, continue to challenge the industry to find higher bandwidth solutions for high quality video transport.”

For Monday Night Football HDTV, ABC uses a mix of Tiernan encoders, decoders and protocol converters to backhaul the HDTV feed from the remote to ABC New York, where further content integration and processing occurs. Then, using the Tiernan hardware, and EF Data modulators and demodulators, distribution to the 32 HDTV-capable ABC affiliates takes place via a 36 MHz transponder on Telstar 4.

Lots Of Challenges,Lots Of Automation

Harris Corp.’s John DeLay emphasizes that on the front end, the challenge is to figure out the best way to effectively implement and manage transport. At the same time, on the back end the challenge is quite different, and the issue of verification is equally complex. And smack in the middle sits the software and hardware, which drives the automation and traffic control systems.

And where does Harris Corp. see lots of opportunities? Its $85 million acquisition of Palo Alto, CA-based Louth Automation, completed in January, is a strong indicator. Harris has recently provided end to end DVB and ATSC satellite distribution systems for MPEG 2 transport delivery for TV Azteca in Mexico and Taiwan-based TTV and CTS.

A gradual, yet steady increase in consumer demand for HDTV programming, the upcoming implementation of digital must-carry by DBS providers, and remarkable strides in IP encapsulation are among the recent developments that the team at Harris is watching closely, according to DeLay. In addition, the rollout of a whole new generation of digital hardware and set-top boxes, which combine 500+ MIPs of processing power with very intelligent software applications, is also of interest.

“The DBS operators are taking the off-air HD signals, backhauling them, and then delivering HD transport as part of their service. They are beginning to sell HD decode-equipped set-top boxes as well,” DeLay says. “We are also approaching the point with respect to the ATSC 19.3 Mbps stream where a very large bit rate is becoming available for non-HDTV purposes. We are no longer dealing with a matter of 4 or 4.5 Mbps out of the block of 19.3 Mbps, rather, we see 8 to 10 Mbps as what we have to work with. This is becoming a reality much faster than many people realize.”

DeLay depicts partnerships as absolutely essential to meeting the demands of the unfolding market as well. He points to the partnering of Harris and Lucent Technologies, which produced an encoding solution known as the Flexicoder, as an excellent example. In the professional receiver products sector, he sees another successful relationship materializing which involves Harris and Samsung.

“We and our partners are looking at potential solutions three to five years out. We are pursuing technologies which deal with both ends of the spectrum,” DeLay says.

Constant Quality Encoding

David Wheeler, marketing director for the media networks division of Scientific-Atlanta Inc. (S-A) in Norcross, GA, indicates that satellite operators like the flexibility of remotely installing Powervu Plus encoders. Once these encoders are installed on site at various cable programmers’ facilities, the operators can backhaul all the feeds, insert any opportunistic data, run the data along with the collocated and non-collocated digital signals through a single multiplexer (mux), and then uplink the final mix.

“In addition, because there is no feedback loop from the mux to the encoder, a Bitmizer statistical multiplexer (stat-mux) can operate with a variable bit rate (VBR) signal from a Powervu encoder located virtually anywhere,” Wheeler says.

And satellite operators are looking to go “condo” as well. “Rather than just providing space segment, they are exploring a condo system, which involves putting in muxes to aggregate resources and programming. This is ideal for delivering multiple program services to the cable headend,”

Wheeler emphasizes that while constant bit rate (CBR) encoding is still seen as a sound practice, VBR encoding solutions have become more widely accepted. What had to happen to make VBR reliable and stable? Temporal adaptation. Wheeler describes this as a process managed in the mux, involving time-shifting the peak bit rate demand from one channel to avoid the peak bit rate in another. This is possible because the peaks are very sharp, or very short in duration.

“The mux needed to be able to perform temporal adaptation to handle the occasional instances when the total instantaneous bit rate, which is the sum of all the VBR bit rates, exceeds the output bit rate of the multiplexer. The latter is always constant, because it is dictated by the bandwidth of the RF or terrestrial communications channel,” Wheeler says.

One result is that “constant quality encoding” has become an important feature, and it is offered in S-A’s Bitmizer statistical multiplexing solution. When an operator matches the MPEG 2 bit rate of the encoder to the most demanding period or scene in the programming, what results is a tremendous waste of bandwidth. The usual pattern involves bit rate peaks which are not only few and far between, but also the average bit rate would typically be 40 to 50 percent below the peak rate.

“Over at Time Warner’s AthenaTV uplink, for example, you can see the tremendous impact of VBR on network operations. Time Warner is using Powervu Plus to run 14 channels in 38 Mbps to their 256 QAM-equipped cable plants nationwide. Even as recently as two years ago, had Time Warner desired to transmit those same 14 channels, it would typically have required 56 Mbps,” Wheeler says.

“You can see why customers can get real excited over VBR. Bitmizer simply takes that a step further. The character of the Bitmizer is such that the encoder does much of the hard work–the VBR–while the Bitmizer efficiently combines the VBR streams together,” adds Wheeler. “And the bonus is that even with such a substantial bandwidth savings, we can still show a customer that at 38 Mbps, another 8 Mbps to 10 Mbps is available for IP data.”

With the open loop architecture of the Bitmizer, the mux does not control the Powervu encoder, so the encoder cannot get starved for bits when another encoder demands more bits. Bandwidth is allocated as demanded by the encoder.

“This is a characteristic of closed loop stat-mux systems situations, where one program causes impairments in another as a result of its claim on the limited resources of the multiplexer. This produces a kind of intermodulation distortion for which the industry has yet to find a name,” Wheeler says.

MPEG 4: The Work Goes On

Any discussion of bit rates eventually turns to the central issue of how low can bit rates go. There are very different assessments from different sources as to the status and role of MPEG 4. Although MPEG 4 is generally perceived as the object-oriented low bit rate cousin of MPEG 2, it is no longer an evolving standard, according to Rob Koenen, project manager in the multimedia technology group at KPN Research in Leidschendam, the Netherlands. Koenen chairs the requirements group at the Moving Pictures Experts Group (MPEG).

“MPEG 4 is still evolving, but not at the frantic pace of a year or two ago. Ongoing work addresses such things as very high quality MPEG 4 for studio use, fine grain scalability, and some systems issues for advanced interactivity. We will see advanced TV services using MPEG 4 as content providers add more powerful and interactive TV content to the mix. Adding MPEG 4 to MPEG 2 is a major focus of activity in many companies, and it has already been demonstrated here in the Netherlands as part of a larger interactive content initiative,” Koenen says.

“MPEG has moved on to MPEG 7, which is really not a coding standard, but rather an attempt to improve the overall management of content through the structured use of audio- visual descriptors and meta-data,” Koenen adds. “Beyond that, MPEG 21 is unfolding slowly, and this should identify and accelerate the development of a new way to universally access multimedia content, regardless of how that multimedia content arrives on your TV screen, or whatever access devices you choose to use.”

Koenen indicates that the MPEG 4 Industry Forum (M4IF) is about to be announced, with companies such as Philips Electronics, Intel, Apple, AT&T, Motorola, Samsung, and Sony expressing an interest in participating. One of the main issues which the M4IF plans to address is the licensing of MPEG 4 technology, according to Koenen, who sees the lack of licensing pools as, “unnecessarily holding back the adoption of MPEG 4 technology.”

Koenen points to Microsoft Corp. as a good example of a company that is already deploying an MPEG 4-based solution in its Mediaplayer. Other companies pursuing MPEG 4-based software and services include Iselin, NJ-based E-vue, which is a Sarnoff Corp. spinoff, and San Diego-based Packetvideo, which is now focusing on mobile and wireless applications.

“MPEG 4 is widely misunderstood. It has been designed for IP-based multimedia applications, and it is not a replacement for MPEG 2, particularly in the area of broadcast- quality video delivery. It is much more software object-based. Stream contents (objects) are composed in the receiver/decoder, and not in the encoder, as is the case with MPEG 2. This flexibility and IP application ‘friendliness’ lends itself more easily to new services such as enhanced and interactive television,” says Divicom’s Goldman.

Goldman describes MPEG 4 as a, “difficult implementation with today’s state of technology.” He agrees with KPN’s Koenen that considerable resources are being devoted to R&D regarding how to support MPEG 4-based applications on a practical transport such as MPEG 2, and how to carry MPEG 4’s object-based content. In the meantime, issues surrounding multimedia applications and IP content for enhanced and interactive TV services are being addressed both by the release of a specification by the Advanced Television Enhancement Forum (ATVEF), and the emerging ATSC DTV Application Software Environment (DASE). With the release of an ATVEF specification, ATVEF-related activities are now shifting to the ATV Forum (ATVF).

Tandberg NDS’s Hobbs believes that MPEG 4 has a place in future coding strategies, and Ovadia Cohen, vice president of marketing for Tadiran Scopus agrees, saying that it has a bright future. However, Cohen reports that, “from a broadcast point of view, this is not something that customers are asking for.

“We have not received any inquiries yet. And concerning the integration of MPEG 4 and MPEG 2 into a single bitstream, we have not faced that either,” Cohen says.

What Customers Want

Tadiran Scopus is encountering two distinct types of customers, according to Cohen.

“The sophisticated customer knows exactly what features they want in a comprehensive system, which include such things as the capability to precisely monitor and control the bitstream, along with all the tools necessary to evaluate picture quality. And then there are the customers that do not even pretend to understand the technology, but know that they need a digital compression system either for satellite, cable, MMDS or off-air broadcasting,” Cohen says.

And what exactly are the sophisticated customers seeking? Cohen describes the list of features as including analog to digital processing at a high level, which includes the capability to deal with jerky or poor signal sources using advanced filtering techniques, dynamic noise reduction and advanced frame synchronization. Besides bit rate and resolution controls, more flexibility with respect to the group of pictures (GOP) structure is also on the list, and specifically the capability to manipulate the length of the GOP so as to better control picture quality at lower bit rates, or to control delays between transmit and receive sites. Some customers are exploring an advanced processing environment for variable and constant bit rate encoding which incorporates vertical interval testing signals (VITS) and vertical interval time code (VITC) for clocking.

“At the network operations level, they want to be able to run the monitoring and control as a subsystem with specific control procedures at the product level. Along with A/V routing and redundancy at the mux, controlling redundancy at the source is important as well, so that in the worst case scenario, if an encoder fails all the information keeps going out to the multiplexer,” Cohen says.

Cergy, France-based Thomson Broadcast Systems, a subsidiary of Thomson-CSF, provides complete broadcast solutions including encoder chip-sets, and offers turnkey systems. According to Bernard Valdenaire, senior marketing manager, Thomson Broadcast Systems guarantees that its customers will receive at least two real-time software upgrades per year. This customer list includes DirecTV’s Galaxy Latin America (GLA), France Telecom (Globecast), Television Per Satellite (TPS) in France, Hong Kong-based TVB, and German DTH providers, ZDF and ARD.

“In general, our customers need more integrated solutions in terms of both video compression software and encoding hardware,” says Valdenaire. “We offer up to 12 encoders in a single box, and more and more multiplexer inputs. It is not unusual to see as many as 16 programs per transponder, using the total throughput up to 38 Mbps.”

“What the customer needs to do first is present us with their set-top box strategy, and then they need to identity their conditional access (CA) vendor. With our emphasis on open architecture, we can interact with all the CA platforms, such as Canal Plus’s Media Guard, France Telecom’s Viaccess, Nagravision, Mindport’s Irdeto, and Telenor’s Conax. After that, we can focus on the global digital architecture, including professional equipment,” adds Valdenaire.

The dual path encoding feature of Thomson Broadcast System’s new DBE-4130 Super-Encoder means better quality at lower bit rates, according to Valdenaire. As for other new encoders, the DBE-4120 contribution encoder includes a built-in ATM interface for telecom applications, while the new DBE-4110 DSNG encoder emphasizes reduced transit time for low-delay transmissions, which is ideal for live remote broadcasts. All these products are based on a proprietary chip set.

Valdenaire sees a number of start-up broadcasters that are leaving their future options open. In other words, they know that once they develop a compelling mix of content, they can move quickly and efficiently into a new market with Thomson Broadcast Systems serving as the integrator.

“With IP-MPEG 2 gateway solutions, these companies can now enter the Internet sector rapidly with a mix of interactive video services that include everything from their own enhanced content to interactive shop-at-home programming, and video game downloads,” says Valdenaire.

Convergence: Sooner Or Later

So, have we entered a new encoding environment? Not exactly, but the door is opening to what is a great win-win situation for everyone involved. As fees drop, at the same time the total number of inbound and outbound streams is increasing, a trend prompted by organizations such as Intelsat, which is now transitioning its global occasional use TV service (OUTV) to digital.

At HBO TWE L.P. in New York City, Bob Zitter, senior vice president for technology operations, believes that the encoding technology has evolved beyond, or “moved past the brute force phase.” Now, he sees the fine-tuning mechanism shifting into high gear as increasingly competitive encoder vendors push the chips, and the algorithms, to even higher levels of performance. At the same time, vendors are offering such features as providing the operator the capability to set channel preferences such that the encoder automatically adjusts its bit assignment scheme to correspond with a programmable hierarchy of channels, selected by the operator.

HBO uses Motorola’s Digicipher 2 SDTV and HDTV encoders at its own uplink facility on Long Island, as well as in its Latin American and Asian operations. As mentioned earlier, parent company Time Warner recently launched its AthenaTV uplink facility using Scientific-Atlanta’s Powervu Plus solution, which is also used by HBO in Central Europe.

Zitter looks forward to another quantum leap forward for digital compression well before the end of this decade.

“Right now, we compress everything in real time as it is happening. This whole dynamic is going to change sooner than we think, with everything or almost everything being pre- compressed and sitting on servers somewhere,” Zitter says.

Dick Tauber, CNN’s vice president for satellites and circuits in Atlanta, serves as chairman of the ITU’s Inter-union Satellite Operations Group (ISOG). Tauber credits the ISOG’s Advanced Technology Operations Group (ATOG), under the leadership of TV New Zealand’s Carl Rossiter, for making steady progress in a number of important areas. With the latest round of MPEG 2/DVB interoperability testing at Intelsat completed as of late 1999, Tauber would like to see several things move along as well, besides further gains in interoperability.

“We don’t have to have interoperability for every encoding or decoding parameter. What is necessary is a set of known and agreed-to specifications that manufacturers, service providers, and end-customers can agree to. That has now been done. With this, you will not have to worry every time your feed takes a double hop. Having low bit rate flyaways, similiar to VSATs, which can generate broadcast quality video in real-time would be a welcome addition. Full-blown video is touching the VSAT side of the market now, and sooner or later we will see some sort of convergence,” Tauber says.

“Nobody is making MPEG over IP, while IP over MPEG is available. Broadcasters would like to see this happen as well, so that MPEG can go wherever an IP carrier exists. It is a contribution issue,” he adds.

MPEG over IP? As you can see, readers are left here with quite a bit to ponder, knowing all the time that the number of channels transmitted via satellite just continues to grow and grow.

As Via Satellite’s senior multimedia writer, Peter J. Brown tracks the satellite industry’s Internet and multimedia applications. He lives on Mount Desert Island, ME.

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