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| The gap in visual difference between film and video has narrowed considerably in the past two years. In the past the best way to describe the difference to a client was: “One looks like Primetime, and the other looks like a Soap Opera.” Now, with the advent of HD, video can begin to look more like film than ever. Which format you use depends on several factors including the target audience, the expected shelf life of the project and of course, the budget. All Broadcast TV stations are required to move to a pure HD signal by 2009, and the move is presenting challenges for the Stations as well as Producers.
Compression / HDTV Update Today’s broadcast compression technology is based on MPEG-2 algorithms. Satellite and digital cable distribution of TV signals are almost entirely based on MPEG-2 compression. These algorithms require between 3Mb/s and 8Mb/s of data to create decent-looking Standard-Definition (SD) video images. At 3Mb/s, MPEG-2 images are only fair quality. At 5Mb/s, MPEG-2 video is quite good. This data-rate is used for most satellite and cable broadcasts. An 8Mb/s data-rate is generally reserved for high-motion or high-end broadcast, such as sports or The Discovery Channel. Satellite distribution of video has become a leading conduit over the last ten years. Data is reflected over these satellites via components known as transponders. Most satellite transponders are capable of transmitting up to 45Mb/s of data. This translates to nine (9) SD video channels broadcast at 5Mb/s on each transponder. Each satellite has several transponders. However, most transponders run at full capacity and digital cable has similar bandwidth limitations. HDTV’s Distribution Challenge: Furthermore, today’s consumer cannot visit their local Blockbuster Video outlet and rent an HDTV DVD, either. The amount of data required to display 90-minutes of quality HDTV video well exceeds the 4.7GBs available via current DVD technology. Sixty-minutes of 10MB/s SD video consumes virtually all available storage on a DVD. Consequently, most commercial DVDs drop the bandwidth back to 6-8Mb/s to allow up to 2-hours of video to be encoded on a DVD. Plus, most consumer DVD players cap out at 8MB/s playback. Sony has been working on a new recordable disc technology called “Blue Laser”, which promises to allow up to 27GB to be stored on media similar to DVD. Blue Laser has been under development for the last several years and was referenced in more than one NAB booth. However, the author was unable to find any working demonstrations other than in Sony’s booth with their HDX disc-powered camcorder. When Blue Laser becomes a reality, new DVD players may be created to take advantage of the new technology. |