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So which is the best format for PS

Discussion in 'Projectors, Screens & Video Processors' started by Clint C, Aug 27, 2003.

  1. Clint C

    Clint C
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    Hi all

    Can I assume that an NTSC DVD will give a better picture than PAL DVD? Or am I way off the mark? :confused:

    Clint.
     
  2. calscot

    calscot
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    Pal is higher resolution at 525lines to 480lines and so all things being equal, Pal will produce better pictures.

    Pal uses 50hz and so shows 24fps films at 25fps and in progressive just shows each frame twice. The film is speeded up by 4% which makes the pitch higher by 1 semitone which is not noticed by most people.

    NTSC uses 60Hz and therefore has to show 25fps by showing 1 frame for 3/60 of a second and the next for 2/60 of a second. This gives means the film runs at the right speed but obviously has a stutter which some people find unacceptable.

    NTSC does not have enough bandwidth to properly show 720 lines by 480 and therefore crops the sides of the picture.

    Pal was introduced later than NTSC and corrected chroma errors that NTSC displayed giving the moniker Never The Same Color.

    Pal is therefore the better format as long as you are not pitch perfect and very pedantic.

    Cheers,
    Cal.
     
  3. Dutch

    Dutch
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    Just to correct slightly, PAL is 576 visible lines, not 525.

    Steve
     
  4. Clint C

    Clint C
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    Thanks guys. :smashin:
     
  5. calscot

    calscot
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    Sorry, I must have been thinking about the total number of lines for NTSC instead of the viewable lines for PAL.

    Cheers,
    Cal.
     
  6. calscot

    calscot
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    One thing I didn't think of is that NTSC has fewer lines therefore lower bandwidth therefore less mpeg compression for the same amount of disc space.

    That could make it less blocky than Pal.

    Cheers,
    Cal.
     
  7. Easy2BCheesy

    Easy2BCheesy
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    Calscot - I'm not sure I agree.

    Correct me if I'm wrong, but NTSC DVD movies are encoded in 29.97fps interlaced regardless of content. 3:2 pulldown is used on that interlaced NTSC stream to bring it down to the 24fps progressive scan movie standard.

    So effectively we're comparing 29.97fps against 25fps - PAL might be outputting more resolution, but NTSC is making up for it by pumping out more frames.

    Am I right?
     
  8. calscot

    calscot
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    There are exactly 24fps in films anyway. Storing 30 frames only means duplication of 6 of the frames and a complete waste of disc space. You cannot put more information in than was there in the first place.

    I think you're saying that NTSC wastes disc space and so cannot use the spare space for lower compression making PAL the much better choice.

    Cheers,
    Cal.
     
  9. They

    They
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    NTSC territory DVDs for 24fps movies only encode 24fps at 720 x 480 4:2:0

    PAL territory DVDs for 24fps movies speed up to encode 25fps at 720 x 576 4:2:0

    The source bit rate difference is about 24Mb/s extra for PAL, that's around 25% more, but that doesn't necessarily relate directly/proportionally to the extra number of bits needed on the PAL DVD to equal the quality of the NTSC DVD in terms of compression. There are many factors in the source and nature of the MPEG2 codec that mean the difference in encoded bit rate is most likely much less than 25%.
     
  10. salacious

    salacious
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    When movies are put on NTSC DVDs the can be transfered at 24fps but with markers through the stream telling it to run at 29.97fps. You don't get the extra fields encoded through the image. This means that the NTSC and PAL version of the movie contain the exact same number of frames, the only difference is that the PAL version have a higher vertical resolution (as well as differences in the colour space converstion, I thought NTSC was 4:1:1 and PAL was 4:2:0). The video can also be either in interlaced or progressive mode. If the disc is properly encoded then it is really easy for a progressive scan DVD player to output the correct information but a lot of the time the markers are wrong.
     
  11. They

    They
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    The 4:1:1 and 4:2:0 differences are for DV not for DVD.

    As for encoding frames, there is a net bit rate of 10.08Mb/s NTSC has to encode 24fps at 720x480 in this space and PAL has to encode 25fps at 720x576 in the same space so there is an extra frame to fit in and extra vertical resolution.
     
  12. clancol

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    we get what your saying guys. but which gives the best picture?
    and is it worth waiting till movies come out on pal to get the extra lines
     
  13. Clint C

    Clint C
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    Thanks clancol, I think the technicalities have overtaken the original question... maybe if I made it clearer by asking this question. Assuming the source is capable of progressive scan - which region disk should we buy to get the best output?
     
  14. Easy2BCheesy

    Easy2BCheesy
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    I'm afraid there's no right answer, it will change on a case by case basis, depending on the MPEG2 encoding, and also on how much bandwidth is taken up with stuff like DTS and DD5.1 soundtracks.
     

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