
chrisribe at gmail
Feb 29, 2008, 11:40 AM
Post #39 of 51
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Re: Hauppauge HD PVR (A bit more info for those starved for it)
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> > > I look forward to the day when more broadcasters actually use higher > > bitrates... Here, only CW and NBC use such a high bitrate. > > > > Mike > > Doesn't CBS broadcast in 1080i too? I thought only Fox and ABC used 720p? > Bitrate, not resolution. For example, here at WCJB-TV in sunny Gainesville, Florida, we use our 19.2 Mbits to broadcast 2 program streams. One is ABC, which is broadcast at 720p , and one is the CW, which is broadcast in a 480i format. Before these signals leave the building, they are joined together in a muxer - a fancy computer that takes one HD-SDI video signal, one SDI video signal, and puts out a single SMPTE 310 signal, which is a fancy name for baseband ATSC, I believe. Anyhow, the muxer tries to squeeze as much video quality into the 19.2 Mbits as it can, and it dynamically reapportions bandwidth between the 2 program streams. When all is said and done, the CW usually ends up with about 5 Mbits and ABC gets about 12.5 Mbits. I honestly do not know what happens to the other 1,700,000 bits per second. The end result is that the CW looks quite good, an ABC does not. Our neighbors at WUFT, the University of Florida PBS station, do things a little differently. They have 3 program streams, one which is usually 1080i and two standard def. The give their HD channel about 14 Mbit and squeeze their SD channels into about 2 Mbit apiece. The half-wits at WOGX (FOX out of Ocala) use their 19.2 Mbits to broadcast an HD and an SD version of the *same thing*. I'm sure the many people stuck with an SDTV and a digital tuner that doesn't downscale appreciate this. -chris -- TV/IT Engineer WCJB-TV Gainesville, FL (352) 416 0648 cribe [at] wcjb
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