Last week’s announcement from Harmonic that it had introduced an MPEG-4 H.264 AVC encoder that promises to reduce the bit rate required to deliver HD via IPTV to the range of 6Mb/s, raised an interesting question.
Will MPEG-4 H.264 encoders save the day for IPTV providers who decide to make their service offering via their existing copper infrastructures, or will such encoders not influence the battle with service providers offering fiber to the home (FTTH) and fiber to the premises (FTTP) in the long run?
HD Technology Update turned to Patrick Pfeffer, chief network architect at telecom engineering consulting firm Detecon, for some insight.
HD Technology Update: What is your feeling about the receptiveness of IPTV operators to include HD channels as part of their programming lineup?
Patrick Pfeffer: Adding HD programming is a must. There is no way around it. HD is in some cases a feature differentiator, but more often a requirement to attain feature parity with existing video incumbents, such as cable MSOs and DBS. The need for HD has forced the fiber-poor IPTV providers (long copper loop) to embrace the still young MPEG-4. HD was so important that IPTV providers are willing to spend more on the more expensive MPEG-4 STB.
HDTU: Will HDTV create a line of demarcation between IPTV deployments that rely on FTTH or FTTP versus those that rely on existing copper infrastructure? Or, will new efficiencies in MPEG-4 H.264 compression keep the latter competitive in terms of HD delivery?
PP: The improvements of MPEG-4 H.264 will lead to a bit rate reduction of about 20 percent in the next few years. There is a lot of room in the MPEG-4 standard to allow chipset vendors to introduce standard-compliant but proprietary algorithms to improve the bit rate. However, this bit rate improvement will happen at the same time as more and more HDTV sets are deployed within the home.
Today, one estimates that there is one HD set in the living room and two SD sets in the bedroom or kitchen. Non-fiber rich network providers serving their subscribers from the central office with ADSL2+ can offer a triple play with one HD, two SD, two VoIP and a few Mb/s for high-speed Internet. However, regardless of the progress of MPEG-4, I do not believe they will be able to serve more than one HD stream, which will become a requirement in a few years.
A last note, in many countries the regulations will forbid the IPTV provider from offering a network PVR. In that case, the PVR would need to be done locally on the STB. Concurrent recording and watching will mandate higher bit rate pipes. The prowess of MPEG-4 will not be sufficient.
HDTU: Can content owners (i.e. broadcasters) do anything to maintain the highest quality possible for their HD programs to be delivered via IPTV networks? Or, are they simply turning over their reputation — in terms of the quality of their HD pictures and sound — to telcos and IPTV system operators?
PP: A digital signal is carried unaltered from its source to its destination. As we often say, “garbage in, garbage out.” Special attention has to be given to the input of the IPTV video encoding and distribution chain. After that you can count on the IPTV providers to carry the bits with the greatest care, meaning no packet loss and minimal jitter. It is, after all, their core expertise.
It is extremely important that content owners for their SD and HD content deliver to the IPTV provider signals of the highest quality. High-quality ATSC is preferred to statistically muxed satellite feeds. While transcoding has improved dramatically, it is something I usually try to avoid for HD content. You don’t compromise HD quality because HD is about quality.
I am tempted to say that in general, an HD video signal is better carried over MPEG-4 than MPEG-2. At the same bit rate, MPEG-4 output will far outclass MPEG-2, and MPEG-4 has built in mechanisms to mitigate for decoder starvation that can result from a lossy signal. An MPEG-2 stream, when starved, will display those annoying green macro blocks on the screen. An MPEG-4 decoder will hide the lack of data to a level imperceptible to most eyes.
HDTU: Are there any unique opportunities HDTV opens to IPTV operators? For example, HD relies on a 16:9 aspect ratio. With more screen real estate than a 4:3 SD display, could that be used in any clever ways to take advantage of IPTV’s interactive capabilities?
PP: It is a good question. HD will allow more interactivity, but more because of its resolution than its real estate. I expect to see a better combination of video and text applications. I believe we will see an HD video browser. The interactivity is more a function of the HD set than of the HD stream.
HDTU: What sorts of added CAPEX demands will HD place on IPTV operators, if any? Will budgetary demands retard IPTV HD deployment?
PP: HD is more expensive than SD. And while the gap is shrinking, it will always exist. For HD content, an IPTV provider needs special satellite receivers, high frequency switches, the storage of HD VoD content requires more hard drives, the bandwidth must be higher and finally an MPEG-4 STB is needed. However, as I mentioned earlier, HD is not an option, it is a requirement. Today, the major problem with HD for IPTV providers is not the cost of MPEG-4 STBs but their availability in quantity and different flavors (hard drive with different sizes for example).
HDTU: Is there anything else you would like to add?
PP: HD is not the end of the road. In a few years, we will have super HD with better resolution and 60fps. With the rapid pace of today's market, not moving ahead with service improvements means falling behind competitively.
In summary, for IPTV providers, a winning product portfolio means HD, and HD means MPEG-4.
