Clipper wrote:
The disadvantage is that the horizontal resolution is essentially cut in half, and the video is often filtered to avoid flicker (interfield twitter) and other artifacts.
It may help to understand the difference by considering how the source images are captured. A film camera captures full frames in intervals that are 1/24th of a second long, whereas a video camera alternately scans fields of odd and even lines in 1/60th of a second intervals, resulting in interlaced frames that are 1/30th of a second long. (Unlike projected film, where the entire frame is shown in an instant, many progressive-scan displays trace a series of lines from top to bottom, but the end result is about the same.)
DVD is specifically designed to be displayed on interlaced-scan displays, which represent 99.9 percent of the more than one billion TVs worldwide. However, most DVD content comes from film, which is inherently progressive. To make film content work in interlaced form, the video from each film frame is split into two video fields —240 lines in one field, and 240 lines in the other— and encoded as separate fields in the MPEG-2 stream. A complication is that film runs at 24 frames per second, whereas TV runs at 30 frames (60 fields) per second for NTSC, or 25 frames (50 fields) per second for PAL and SECAM. For PAL/SECAM display, the simple solution is to show the film frames at 25 per second, which is a 4 percent speed increase, and to speed up the audio to match. For NTSC display, the solution is to spread 24 frames across 60 fields by alternating the display of the first film frame for 2 video fields and the next film frame for 3 video fields. This is called 2-3 pulldown. The sequence works as shown below, where A through D represent film frames; A1, A2, B1, and so on represent the separation of each film frame into two video fields; and 1 through 5 represent the final video frames."
Clipper that went over my head... as far as my knowledge goes, I have not seen anywhere (esp the MPEG-2 standards, yeah being part of my research work), that DVDs are meant to be displayed on "interlaced displays".
You have made an understatement that "filtering" is done to reduce the "twitter" . Infact that is what is done in the "Auto-select / Force-Bob method" of PowerDVD and you can see the effect. Believe me De-interlacing is an anathema for image processing engineers and what is done today, is not an optimal solution. However that should be used for material that have been previously recorded in a video mode (e.g. TV shows, concerts etc. ) and not films !
I have posted some links from the Charlie Chaplin DVD's ( yeah ur Fav hollywood companies), which reveal blurring effects due to conversion from a PAL master to NTSC.
What Rana's and Dragun's point is that if a film is telecined in PAL then it should be encoded in PAL (as you have pointed out). However that is not the case.
I think you may have been short-handed by DEI... else I am surprised how can u ignore from your posting abt a dvd like
Kaho Na Pyar Hai...(another Rakesh Roshan Film and I love that transfer.. absolutely flawless.. comparable to any Hollywood dvd !)
When I can get such stuff, why should I settle for anything less ? Unfortunately it is ppl who have the "indian-dvds-what-else-can-you-expect" attitude, is the reason for such a state we have now.
Ppl want dvds, no matter what the situation is, and as a result quality suffers !
DEI/BEI was/is the only company that actually focusses on quality. I hope AYNGARAN can be another such company. YashRaj..no way... they also believe in the cost-cutting-attitude that has plauged all non DEI-dvds (DEI also cuts-cost... If you notice, no motre inlay cards
).. whish is whY I openly advocate pirating all Non-DEI / BEI dvds... or even copying them. I dont think its worth copying a DVD that is priced at 7 or 8 bucks anyways !..