by Derek Kerton

The Paradox Of HDTV Capacity

Usually, being a first mover is an advantage, but in the satellite, digital cable, and Over The Air (OTA) broadcast TV world, having digital compression at the network core is impeding Satellite and Cable's move to HDTV. I'm linking this post to one Mike wrote on Cablevision's Voom HDTV satellite service, because the idea behind Voom was to focus on HD content, and beat out Dish and DirecTV, who would offer less HD. Why is it that these very modern, all-digital, 'space-age' companies are not offering all HDTV? It's because of network capacity. Classic analog broadcast TV uses about five times the bandwidth of HDTV, and only delivers a fraction of the image resolution. So an OTA broadcaster can upgrade to HDTV, and actually reduce the bandwidth that they use. However, to keep costs down, satellite providers were always looking for ways to increase the system capacity of their networks, so years ago they got smart and took the analog TV signals, compressed them to MPEG2 digital signals, and then send them to your set-top box, which decodes the MPEG2 back into your old analog TV. But now when TV programs upgrade from low def analog to HD digital, the satellite guys have a problem - they were already gaining the compression benefits of digital, and had already filled their capacity with many, many channels of digitally compressed low def. They don't have the capacity to increase the resolution of those channels to HD. This is why digital cable, DirecTV, and Dish all have only a few select channels available in HD. They will need to launch additional satellites, and build the core capacity needed before they can provide a full range of HDTV programming. Meanwhile, OTA broadcasts, by virtue of being wasteful and out-dated, suffer none of these problems, and thus to leap into the future and get HDTV, many people are going back to the future by installing rabbit ears and rooftop antennae to pick up OTA HDTV signals.

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  • identicon
    Anonymous Coward, 23 Dec 2004 @ 10:04am


    Cable takes a different route and reencodes the HDTV signal at much lower bitrate. I was watching The Matrix: Revolutions on Comcast and the MPEG encoding was breaking to pieces on any scene with high contrast changes (almost all of the fight in zion). It was so bad I had to switch back to the non HD version and watch the rest in standard. It no longer surprises me to have an HD signal show MPEG artifacts quite often during the programming.

    reply to this | link to this | view in chronology ]

  • identicon
    ted, 23 Dec 2004 @ 10:04am


    couldn't agree with your more

    reply to this | link to this | view in chronology ]

  • agree, but im still confused about MPEG2 digital signals

    reply to this | link to this | view in chronology ]

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