Hyper Shinchan wrote:
How does the analog to digital transfer differ? How does it influence the quality of the transfer and especially why should it cause problems with sources that are already digital?
NTSC is an acronym for the National Television System Committee, and certain standards have been set by them so that all televised video is compatible to all of the devices used to play those videos.
Nowadays, the only standards that really matter anymore is the size of the video and the pull-down frame-rate of the video, which changes when converting 24 fps film into video for VHS, television, or DVD. NTSC has the video's size at 720 x 480 at all times. The difference between wide screen (16:9) and academy size (full frame, or 4:3) is merely the length of the pixels, but it's still the same amount of pixels (720 x 480), bit in wide screen, each pixel (short for "picture element", a carry over from film prints and not referring to the little light bulbs on your computer screen) is stretched into a 16:9 aspect ratio (16 across by 9 units down) rather than shaped into a 4:3 aspect ratio (4 units wide by 3 units down). An NTSC formatted DVD really means that the size of the video is 720 picture elements across by 420 picture elements down, with the aspect ratio of those picture elements differing depending on shape of the picture you want.
The frame-rate changes with NTSC as well. Usually, stuff shot specifically for NTSC runs at 29.97 fps. This is why most television shows are shot at that frame-rate. But film is still shot in 24.0 fps. So NTSC will use the 3:2 pulldown to change the frame rate to 23.976 fps to help compensate. This results in adding about 7 seconds to a 2-hour film, which nobody every really notices.
There's also color encoding requirements and all of that stuff.
There's another method of formatting not used in the States called PAL, which has the video size of 720 x 576 picture elements. This give greater vertical resolution, and I believe the aspect ratios of the picture elements are also adjusted to something different that 4:3 or 16:9 shapes, but since the PAL system is only used in South America, I never really got around to learning the ins and outs of that system.
And since NTSC is a national thing accepted by most other countries, that means of you're watch a TV show or playing a DVD built for the broadcast technology you're using, it's encoded to the parameters set by the National Television System Committee.
All that to say that Blu-ray isn't formatted in NTSC, which gives more precise displays of picture elements and frame rate. High definition broadcast technology is much different than standard broadcast technology, but also comply to other standards, probably set by the formatting the films themselves are made in. I think some TV shows have also begun recording in non NTSC formatting, and have switched to using film standards within terms of frame-rate and picture elements and compensating by using the 3:2 pulldown for some syndicated television broadcasts.