MPEG-4: DSL's HDTV Dilemma

The latest video compression standard to come out of the Motion Picture Experts Group has pretty much swept aside other rivals to become the clear choice for new IPTV deployments. MPEG-4 AVC (also known as MPEG-4 Part 10; and, because the standard was co-developed with the International Telecommunication Union (ITU) further known as H.264) is now widely supported by makers of chipsets, encoders, and set-top boxes. It already offers a 50 percent improvement in compression compared with the MPEG-2 standard it replaces, with further improvements expected. MPEG-4 AVC's compression prowess substantially reduces the bandwidth needed to offer IPTV services, leading the growing ranks of would-be IPTV providers to consider deploying services for many more customers.

It's clear that MPEG-4 will enable network operators to offer more robust video services across the board. But as the current issue of Light Reading Insider shows, even MPEG-4 may not be robust enough to solve long-term problems for certain types of service providers – specifically, those delivering video services over conventional DSL networks.

As the report details, the bandwidth limitations of many DSL networks can be compensated for with MPEG-4, but they can't be completely solved. The good news for DSL network operators is that with MPEG-4, they can deliver standard-definition IPTV services that can compete with video offerings from other types of service providers. The bad news, if you haven't guessed, is that the playing field tilts decidedly against DSL when high-definition TV enters the service equation. And it's clear that consumer demand for HDTV programming is growing significantly.

Vendors currently estimate that with MPEG-4 AVC, real-time SDTV can now be delivered to a sufficient level of quality using 2 Mbit/s to 3 Mbit/s of bandwidth. This is now clearly possible for many if not most DSL customers. But HDTV currently requires anywhere from 6 Mbit/s to 10 Mbit/s per channel, depending upon the fidelity of the video stream. Add in the requirement to deliver a high-speed Internet connection and voice service on the same line, and the bandwidth requirement goes up even more. Then tack on the need to deliver a second or even a third HDTV stream to accommodate simultaneous viewing or recording of other real-time content, and even robust DSL-based networks won't be able to keep up.

Light Reading Insider estimates that more than half of all U.S. homes still cannot get sufficient DSL bandwidth to receive a single HD channel plus concurrent broadband access at 5 Mbit/s. Even with further projected improvements in compression, it seems unlikely that MPEG-4 can make DSL video services competitive with or comparable to those delivered over FTTH, cable, or satellite networks as the market moves toward HDTV.

As one encoder vendor noted to Light Reading Insider, “Operators deploying fiber-to-the-home are looking pretty smart right now.” The long-term picture for copper-based DSL network operators is decidedly less clear.

The latest Insider takes a detailed look at the state of video compression in the IPTV industry. It discusses what MPEG-4 AVC is, and its impact so far on the delivery of IPTV services. It looks at the AVC/H.264 compliant products now on offer from leading encoder vendors. It reviews how the vendors can further improve compression rates, and explores the levels of improvement we might actually see. It then goes on to review what those improvements might mean for the supply of competitive IPTV services over DSL in the United States.

— Simon Sherrington, Analyst, Light Reading Insider

MPEG-4: DSL's HDTV Dilemma, a 23-page report, is available as part of an annual subscription (12 monthly issues) to Light Reading Insider, priced at $1,595. This report is available for $900. To subscribe, please visit: www.lightreading.com/insider.