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Where in the replay chain do you lose the differences between PAL and NTSC?

Discussion in 'Projectors, Screens & Video Processors' started by Welwynnick, Aug 24, 2005.

  1. Welwynnick

    Welwynnick
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    I’ve been thinking about importing a 1080p DLP RPTV from the US. The price/performance is very attractive, but every man and his dog is quick to point out all the downsides to doing this, so I don't want to go all over that again. Being able to plug in a DVHS player would be nice, but I’d like a bit more future proofing than that. The fundamental obstacle seems to be that US TVs are NTSC only. I had always assumed that using a scaler would not be the solution, but I’m questioning that now.

    I’ve shied away from properly understanding TV ever since my university lecturer brushed off colour TV: “Oh that’s all very clever, very complicated. We don’t have time to go into that.” And that was an electronics degree! But now I am wondering what the fundamental processes that TV really performs are:

    1. Capture a moving picture at 50Hz
    2. Scan the picture into 576 interlaced lines (RGB video)
    3. Convert RGB video into component (luminance + red complement + blue complement)
    4. Convert component into luma + chroma
    5. Encode luma, chroma and audio into composite
    6. Modulate composite onto RF

    Yes, I know it’s much more complicated than that, but I’m just trying to account for the differences between NTSC and PAL that affect us. The important thing seems to be that each one of those processes are different for the different standards. However, when videophiles take, say RGB from a STB or DVD and process them with a scaler, they are hopefully left with the original very basic RGBHV video signal that is processed back to the native resolution and frame rate of the display.

    That display, whether it happens to be a TV or not, is acting as a monitor. Doesn’t a monitor take video at a low enough level for there to be no more differences between the original video standards? So, as long as I use it as a monitor (which I would anyway), can I use a US TV in the UK?

    Nick
     
  2. pjskel

    pjskel
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    If you do plan on bringing a US TV into the UK, you ARE going to need some sort of conversion device (scaler/processor being the optimum obviously) to convert 50 Hz signals into 60 Hz, which is all the display is likely to understand or cope with.
    Also, SD PAL transmissions will need to be either converted to NTSC for the TV to handle, or upscaled to 720/1080 @ 60 Hz. Personally, I don't see the point, esp with the weight meaning it'll cost a shedload on shipping, and what do you do in the case of a non-working unit on day one or day 364? Send it back for repair?
    To me, somethings are just not worth the hassle of importing, nor the cost - savings aside (if any), and you'd be better to remain patient a little longer, as 1080p products are coming soon enough. But, it's your call and your money.

    Parts 5 and 6 of your post I don't follow - surely composite is deconstructed to its base elements, and RF is the input which Composite rides on - the RF part is removed leaving composite to be deconstructed.
     
  3. Welwynnick

    Welwynnick
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    The numbering of the processes was meant to represent the broadcast, which is simply turned on it's head for receiving.

    I know all about the downsides - lord knows there are enough of them - they have been covered to death in the DLP forum. But no-one there seemed to fully understand scalers. I hoped someone here might know if the video output from a scaler had lost all of it's original PAL/NTSC characteristics.
     
  4. pjskel

    pjskel
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    I'm having to guess here, but seeing as the images have been processed to the new output modes of 720 or 1080, then the only remnant left of PAL/NTSC is going to be the frequency it refreshes at - 50/60 Hz respectively.
    Otherwise, we'd still be no better off.
    But, I'm curious, what defining characteristics do you consider PAL/NTSC to have, that you think MIGHT be carried over once scaled?
     
  5. Welwynnick

    Welwynnick
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    Colour coding.
     
  6. gizlaroc

    gizlaroc
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    One problem is the 50 to 60Hz conversion.

    Set your dvd player to NTSC and play a PAL film, see the judder? that is what you will get with anything pal. Complete waste of time.

    How much would you save? I wouldn't pay £100 for a screen if you had to FRC with anything, I have returned 2 plasmas because of this feature alone.
     
  7. gizlaroc

    gizlaroc
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    Your scaler would output RGBhv or YUV into the screen, and if it was a 1280x720 panel you would output everything to 1280x720 at 60Hz, pal ntsc does not come into it, the screen will think it is a standard HD resolution.

    You may even find that most dlps will take 50hz anyway, ask someone with a HTPC and the model you are looking at to try it.
     

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