DENVER
The National Academy of Television Arts and Sciences recently awarded a Technical and Engineering Emmy to DirecTV and Tandberg for their development and deployment of an MPEG-4 Advanced Video Coding (AVC) systems for HDTV.
To learn more about the technical breakthrough behind MPEG-4 AVC and its implications for the television industry, TV Technology spoke exclusively with Romulo Pontual, the chief technology officer and executive vice president for engineering at DirecTV, a News Corp. company.
TV TECHNOLOGY: Please describe what led up to DirecTV's development of MEPG-4 AVC.
Romulo PontualPONTUAL: We first asked ourselves how we could rebirth our activities to be a national leader in HD while preserving our existing services.
We saw by 2004 that the challenge was how to transition our satellite broadcasts from normal standard television to high definition. There was no technical standard for transmitting HD by satellite, and the nascent compression technology for HD still needed more testing before it was ready for commercial use.
After much research, we finally realized that we needed more satellite spectrum capacity and we needed new equipment to transmit in HD.
TV TECHNOLOGY: How did you go about doing that?
PONTUAL: We started three major projects. The first was to expand the satellite fleet to be able to handle our transition from SD to HD. The next project was to change our transmission system to make it compatible with the new satellites for HD. The last project was to introduce a new compression method suitable for HD.
TV TECHNOLOGY: Can you say more about the compression project? Is that where Tandberg became involved?
PONTUAL: Yes, we worked hand-in-hand with Tandberg as our compression supplier to develop and prove the technology we felt had the capacity to provide the quality we wanted. Together we decided that only MPEG-4 AVC could give us the compression rates and quality we wanted to obtain. Tandberg's competence in HD enabled us to jump-start our efforts.
TV TECHNOLOGY: Is your MPEG-4 Advanced Video Coding compliant with the H.264 block-oriented motion-compensation video compression codec developed by the ITU-T Video Coding Experts Group (VCEG)?
PONTUAL: We started with H.264, also called MPEG-4 Part 10, because we needed to reliably uplink content at high data rates. This was possible with MPEG-4 AVC, but its use had to deliver a high quality video and audio experience live in real time. And we needed a reliable device associated with it at the headend.
We did all this by introducing MPEG-4 AVC with satellite availability of HD at the same time as we introduced our new HD set-top boxes. We were able to create a new experience for consumers in record time. We see this Emmy as recognition of our ability to move from SD to HD so quickly and with such high quality.
TV TECHNOLOGY: Please describe the development process in more detail.
PONTUAL: Back in 2004, there were more MPEG-4 skeptics than believers in the ATSC community. MPEG-4 was more of a lab thing. It was not yet in place anywhere. We began working with MPEG-4 AVC to see what it could deliver.
Because time was short, we developed a video compression encoder with Tandberg at the same time as a silicon chipset for a new MPEG-4 set-top box was being developed with Broadcom. We worked with Dolby for the HD audio quality. This required strong team cooperation among the multiple suppliers working with DirecTV to make sure all the technologies worked together end-to-end.
We had to work out such details as signal synchronization at variable data rates, or how to verify audio quality from encoding to reception. It became a night and day project with lots of pizza dinners in the DirecTV labs.
As part of that process of developing MPEG-4 AVC, by the way, we also changed to DVB-S2.
TV TECHNOLOGY: DVB-S2 is the second generation of the satellite transmission standard for Digital Video Broadcasting in Europe, ratified by ETSI in 2005 and intended for use with H.264. However, DirecTV has never been fully DVB compliant since it adopted a rather early iteration of DVB-S, calling it DSS. Does this mean that DirecTV is now replacing DSS in favor of full compliance with DVB?
PONTUAL: We are changing to DVB-S2, the new European standard, to enhance transmission quality for HD because it operates at higher frequencies. DSS is limited to SD transmission, and it will be phased out when it's no longer needed for SD. There's no need to replace DSS for SD. As consumers move over to DVB-S2 for HD, they one day will no longer be interested in SD, and that's when we'll drop DSS.
TV TECHNOLOGY: Does this mean replacing all the older DSS dishes and set-top boxes?
PONTUAL: Yes, consumers will need to replace their dish because we've added new slots. There were three orbital positions for ATSC transmissions and now there are five. The new dishes can receive from all five slots at once. Any home that wants to receive HD needs to switch to the new dish.
TV TECHNOLOGY: What would say has been your biggest challenge in converting to HD?
PONTUAL: HD required a huge revamp of our program guide. The program guide today has thousands of entries for every local station in the United States. Every channel in the guide displays only the content that matters to that home consumer, yet the transmission itself carries graphics, program synopsis, actors' names, and other data that has to be kept current in real time. We had to rework the guide from an SD format to an HD format, and we had to make it compatible with MPEG-4 AVC.
TV TECHNOLOGY: Did this involve renegotiating your patent licensing with Gemstar/TV Guide?
PONTUAL: We license the Gemstar patents, but 100 percent of our program guide code was written by DirecTV, and this covers everything from the headend to the box, including all the scheduled programming and all the programming offered on-demand. We have 130 channels across the platform carrying HD content 24/7. The guide carries content specific to 91 local markets, and all this changes day by day while the overall volume of data grows month by month. It's a constantly moving target.
One unique feature in the guide is the "Game Search" function. If a game is being blocked out on a specific broadcast station in your area, how can you find out if any of the other 300 channels on DirecTV are carrying the game? With Game Search, the DVR in your box searches the entire guide to find a licensed source for the game, such as ESPN, and then offers that choice to you. We had to make sure that feature would work properly in the MPEG-4 version of the guide, and that took a lot of work.
TV TECHNOLOGY: What would you say are the implications for the industry of your achievement?
PONTUAL: Five years ago, it would have been impossible for any system operator to offer so many HD channels in the binary transmission mode of MPEG-2. Even 20 channels in HD would have been significant. Now we can offer more than 100 channels in HD, and one day every channel may be in HD. We're just beginning to get to the level that full HD service is possible.
DirecTV has established our leadership in HD due to a successful cooperative effort with other technology leaders like Tandberg. Nobody really trusted when this transition began that HD would gather the momentum it has today. Soon you will be able to get HD television anytime anywhere across a range of devices. We plan to be part of that.
