Advanced Imaging


Image Processing

Updated: July 8th, 2008 05:26 PM CDT

Migrating to Advanced Video Coding: What's the Plan?

via NewsEdge Corporation

It's no secret that something better than MPEG-2 video compression is emerging. In fact, there are two video coding methods that are better. Both AVC (also known as MPEG-4 Part 10) and VC-1 are better. They can provide the same picture quality as MPEG-2 in about half the bandwidth. So a TV broadcaster, instead of using a full 6 MHz channel to carry an HDTV program, could use that channel to carry both an HDTV program and a bunch of SDTV programs. It's technically feasible. But neither broadcasters nor cable operators nor TV manufacturers have figured out how to get to AVC or VC-1 from where we are today.

Broadcasters have staked their claim to an approach that retains the same data rate (19 megabits per second), in their six-megahertz channel, but uses a kind of time division multiplexing to interleave signals using MPEG-2 coding with signals that can use advanced coding. This approach allows "legacy" receivers to ignore the signals with the advanced coding. But it eats into a broadcaster's payload capacity.

Broadcast satellite operators have plans to use advanced coding in the near future, and have actually selected AVC as the one they plan to use. They have a more urgent need to migrate to advanced coding because otherwise they would not have the capacity to carry all the HDTV programming?both satellite services and local broadcasters?that is expected in the next few years.

For the most part, existing consumer electronics hardware can't decode AVC or VC-1. So that means new hardware must be introduced. There are currently about 18 million DBS subscribers, so a lot of new set-top boxes will be needed. But DirecTV and EchoStar can manage their rollouts on a region-by-region basis because of new spot-beam satellite technology. And they can use rebates and tie-ins in the same way that cellular operators do: a free set-top box if you sign up for a two-year subscription.

Cable operators don't feel the same pressure to increase their network capacity by moving to advanced coding. But that could change. If it does, advanced coding can be deployed system by system, using new set-top boxes to do the decoding. But as cable-ready ("plug and play") digital TV receivers are deployed more widely, the cable industry's ability to introduce new technology like advanced coding becomes more constrained.

1 2 3 next

Subscribe to our RSS Feeds