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H.264:
H.264, or MPEG-4 Version-10 / AVC, encoding algorithms differ from those of MPEG-2 in that they scale upward and downward more linear in bandwidth, with better quality at lower data-rates. MPEG-2 algorithms do not produce good quality video at much less than 3Mb/s on the low end. On the high end, MPEG-2’s quality-increase curve tends to flatten out much quicker than that of H.264. H.264 scales well (more linear) in both directions, producing acceptable quality SD video at data-rates in the 1-2Mb/s range and HDTV video at between 6-10Mb/s. At a given quality level, H.264 can save as much as 70-80% of the bandwidth required to distribute programming!
This new approach promises to help eliminate the bandwidth challenge and provide HDTV a long-needed distribution mechanism. Hidden in small back-wall booths at NAB, H.264 “technology demonstrations” were available to those that were persistent enough to find them.
Vendors such as Modulus, Envivio, and LSI Technology displayed impressive H.264 playback technology. Modulus showed very respectable 1080i HDTV video at 6.1Mb/s, with others also demonstrating similar quality at 7-10Mb/s! These vendors also showed impressive SD video at 1-2Mb/s!
Microsoft WM9
Microsoft’s Windows Media v9 was also demonstrated in several booths as an MPEG-2 / H.264 alternative. The SD and HDTV quality of WM9 was a close rival to H.264. WM9 uses very similar encoding algorithms to H.264 and produces similar quality video at a given data-rate. Tandberg demonstrated real-time WM9 HDTV encoding, but at an undisclosed price (read $ pricey).
The Future
Will H.264 and WM9 replace MPEG-2 as the compression flavor of choice for the broadcast
industry? It is not only likely, but probable!
Broadcasters
Broadcasters are scheduled to relinquish their analog frequency spectrum in 2007 in exchange for a tighter digital spectrum. This digital spectrum will limit data distribution to under 20Mb/s, adequate to transmit up to three decent-quality, MPEG-2-based, Digital TV (DTV) SD channels of video at 6Mb/s or one half-way decent HDTV signal. Implementation of one of the more efficient compression techniques described above would allow one excellent-quality HDTV signal and up to four excellent-quality DTV SD channels.
Minimal necessary changes to the broadcasting plant will make a move to new compression technologies less painful than anticipated. Current digital routing, switching and internal distribution can all remain relatively static. The new reduced data-rates will allow HDTV to be routed at under 50Mb/s, well within the range of most distribution gear today.
Digital Cable and Satellite Distribution
The number of channels that these “mail-men” of the industry can deliver is limited by the size of their data pipes. And, their data pipes (satellite transponder & terrestrial fiber/copper/router/switch components) are not quickly or inexpensively updated. The number of channels that can be delivered can have a direct impact on the number of subscribers and the revenue that they generate for their provider. If a provider can now provide 250+ SD channels and a half-dozen HDTV channels, one of these new compression solutions would allow 400+ SD channels and over 150 HDTV channels!
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