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Originally Posted by nuttyinnyc 
Thanks John, A little bit too technical but very satisfying as an answer. But in human terms you are just saying HD channels just broadcast on a better speed then their sister SD channel which in turn gives us the better signal even for the SD shows on a HD channel. Am I right?

Thanks John, A little bit too technical but very satisfying as an answer. But in human terms you are just saying HD channels just broadcast on a better speed then their sister SD channel which in turn gives us the better signal even for the SD shows on a HD channel. Am I right?
Exactly. The upconversions to 1080i or 720p require that higher bit rate.
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Also your response brought out another question. You said "Stations usually upconvert their 1080i/720p sourced from 480i SD with high-quality pro hardware."
Are shows that are broadcast in HD not filmed in HD(like the night time network schedule)? Is everything we see upconverted? Or are you saying that everything that is SD on a HD channel is upconverted to look better even though it is not a true HD program? Just trying to make sure I am reading right, thanks again John
Also your response brought out another question. You said "Stations usually upconvert their 1080i/720p sourced from 480i SD with high-quality pro hardware."
Are shows that are broadcast in HD not filmed in HD(like the night time network schedule)? Is everything we see upconverted? Or are you saying that everything that is SD on a HD channel is upconverted to look better even though it is not a true HD program? Just trying to make sure I am reading right, thanks again John
When the original source is 480i, usually programs appear 4:3 on HD channels after upconversion to 1080i or 720p. There are tricky exceptions. Watched a nature show from WNET HD last night about a lake system near Croatia. It originally was 480i 16:9, and after upconversion the remarkably crisp images fooled me during an earlier viewing into thinking it was true 1080i. But upconversion to 1080i from 480i can't provide details to make all images look like true 1080i. So shots of distant forests at the end of this PBS nature show revealed how fuzzy finer details were, distinguishing between SD and true 1080i.
Shows such as NBC's Leno are recorded (tape/disks) and broadcast at 1080/60i (true HD). They're crisper (as well as live 1080i or 720p) because there's no intervening conversions from film. Also, filming captures images at 24 frames per second (fps) and some programming is taped at 24PsF (segmented frame), emulating filming. Motion with 24 fps capture (1/48-sec exposure/frame) is blurred more than with documentaries/travelogues, live TV, Leno, etc. captured at 60 'snapshots' (540-line half-frames) per second for 1080/60i. Elaborated on some of this in a Blu-ray forum post . -- John






















