The evolution toward more advanced video compression codecs is creating new opportunities and challenges for content providers. The transition from MPEG-2 to MPEG-4 has helped to shrink the bandwidth required for SD and HD programming, but the transition requires new capital expenditures and business challenges.
A new standard is being developed for High Efficiency Video Coding (HEVC), or H.265, which promises to deliver 30 percent to 50 percent more efficiency than the H.264 standard. Dave Kummer, CTO, EchoStar, says that the first HEVC equipment is expected to rollout next year.
“H.265 will allow EchoStar to efficiently deliver 4K and better 3-D services to customers, and perhaps use it in green-field operations to significantly reduce bandwidth requirements,” says Kummer.
The transition towards HEVC could take five to seven years if the economy is slow, but may come faster if terrestrial TV broadcasters adopt it. Richard Doherty, a research director at technical analysis firm Envisioneering Group, says, “The real key part of this is what the broadcasters may do with H.265, since they are currently stuck with MPEG-2 for broadcast TV. If they go to H.265 for the next generation of over-the-air broadcasts, that would change things more dramatically. If they make the decision in 2014, that will have a huge effect on satellite and cable adoption.”
The MPEG-2 compression standard has matured significantly since it was first established in 1996. Better encoders have helped to reduce the bandwidth required from 8 Mbps to as little as 2 Mbps. At the same time, the cost of the encoders has dropped significantly. The decoders are also being built into standard digital TVs, which has helped to further reduce the costs.
“99 percent of all Americans will get TV in MPEG-2 between now and Christmas,” says Doherty. In the United States, all digital TV is MPEG-2 based, except for a few ATSC mobile DTV channels being delivered in MPEG-4.”
The Dawn of MPEG-4
MPEG-4 (H.264) content distributors are seeing a 40 percent to 50 percent gain in bandwidth, allowing almost a doubling of channels. However, this gain decreases for some of the live sportscasts that have to be at a higher quality rate or for other content when there is a contract clause.
MPEG-4 makes the most sense for DTH operators like Dish and DirecTV as it allows an operator to transmit more content over limited satellite bandwidth. Doherty notes, “In North America, we see Dish embrace MPEG-4 more than DirecTV, which still has a lot of MPEG-2.”
DTH operators are upgrading consumers when a hard disk drive used for PVRs fails. Doherty explains, “When you have a PVR box that fails that is a good time to upgrade. EchoStar has been doing it for four years, and DirecTV for about three years.”
However, this can lead to bandwidth inefficiencies when the DTH operator has to maintain parallel MPEG-4 and MPEG-2 broadcasts. Doherty said some channels are duplicated. For example while some of the newer HBO channels are only sent in MPEG-4, some of the older channels like HBO East and HBO West are still simulcast in both MPEG-4 and MPEG-2. Doherty explains, “My understanding is they still have millions of MPEG-2 only receivers out there.”
Kummer says EchoStar has already moved to MPEG-4 for all its HD services, and has taken the pain of replacing customer HD MPEG-2 set-top boxes in the field to allow them to move to MPEG-4. “We were fortunate that we made the switch to MPEG-4 as soon as possible to reduce the cost of field replacement,” he says. “In fact, we are certainly the largest MPEG-4 service provider in the world (remember, we have Eastern Arc all MPEG-4, as well as Western Arc at MPEG-4 for HD). The bandwidth benefits have certainly been well worth it in the long run.”
For over-the-air broadcast, some U.S. operators are testing out MPEG-4 for distributing smaller format video for mobile devices using only 10 percent to 20 percent of the bandwidth of a conventional MPEG-2 signal. Only three cities in the United States currently have a substantial lineup of MPEG-4 over-the-air broadcast channels including Washington, D.C., Chicago and Seattle. A few others cities including New York and Dallas are testing the services on one channel. These signals can be decoded using a pocket receiver produced by RCA, Samsung or Hauppauge Computer Works.
Vendors are also working on various approaches to squeeze even more bandwidth. Benoît Fouchard, chief strategy officer at Ateme, says, “On the compression efficiency front, our latest generation of hardware encoders now implements all the tools of MPEG-4, even some that were perceived redundant in the earlier days of MPEG-4, such as PAFF versus MBAFF. These are two techniques to switch between interlaced mode and progressive encoding. And we found that by combining the two, we get even more efficiency than by using just MBAFF.”
Ateme is also working on better visual models for quality that are perceived by the human brain as opposed to machine measurements. For instance, they have developed algorithms to analyze the content and identify areas of interest where the human eye will naturally focus so that it can then allocate more bits to code that area perfectly, possibly at the expense of a meaningless background.
Other techniques, like Ateme’s Smartrate, focus on optimizing video quality over multiple channels. “To deliver good and constant quality on a single channel, the encoder is making decisions on how to allocate the available bandwidth across multiple pictures, and across macroblocks and line within a picture,” Fouchard explains. “What the Smartrate does is that it extends that optimization across multiple video channels. So when one channel needs less bandwidth (for example, because it is a fixed camera with little motion), that bandwidth is made available to enhance another channel on the same pool. The whole pool bandwidth (typically a full transponder) is constant, but individual channels consume more or less bandwidth over time depending on their complexity.”
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