1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

PAL/NTSC formats

Discussion in 'Projectors, Screens & Video Processors' started by NicolasB, Oct 4, 2002.

  1. NicolasB

    NicolasB
    Well-known Member

    Joined:
    Oct 3, 2002
    Messages:
    6,070
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Emily's Shop
    Ratings:
    +669
    Not sure if this might be better posted in the AV Equipment forum, but we'll try it here first....

    I'm curious about the difference between american and British DVDs, not so much in terms of the region 1 / region 2 encoding, but in terms of the differences between PAL and NTSC.

    The PAL television system uses 625 lines (about 580 useful lines) and displays 25 frames per second (using interlacing, so 50 half-frames per second). NTSC uses 525 lines (about 480 useful) and 30 frames per second (again, with interlacing).

    So, questions:

    1) If we ignore progressive scan for a moment, does the output from a PAL DVD actually have a higher vertical resolution than the output from an NTSC disc on the same player?

    2) How do they go about putting a cinema film (24 frames per second) onto an NTSC disc? And is the process the same for PAL? I know that when they show films on UK television they actually speed them up slightly and show them frame for frame. But showing films on NTSC television is more complex. I believe they have to blend together successive frames. (You get a similar effect watching american shows on British TV). Does this imply that the individual frames on a PAL disc are sharper than those on an NTSC disc (for example if you freeze-frame it, will you always see a sharp rather than blended picture?)

    3) To be able to play back an NTSC disc on a multi-region enabled player, to what extent is it helpful or necessary to have an NTSC-compatible television?

    4) Does anyone have any idea when a PAL progressive scan standard will be finalised? And how many current progressive scan DVD players will be able to support it, if any?
     
  2. Gordon @ Convergent AV

    Gordon @ Convergent AV
    Distinguished Member AVForums Sponsor

    Joined:
    Jul 13, 2000
    Messages:
    14,013
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Living in Surrey, covering UK!
    Ratings:
    +2,809
    1: Yes. The PAL system has more vertical resolution. So a PAL VHS would have more vertical resolution than a NTSC DVD....

    2: FILM = 24 FRAMES per second. First thing both do is interlace this to create two FIELDS for each frame. So now we're at 48Hz. ie 48 fields per second. For PAL they just spead it up as you have already noticed. This gets them to 50 fields per second and the film is over faster.....NTSC still needs another 12 fields to get to 60 Hz though. So what they do is this.

    Frame FIELD
    1 1
    1 2
    2 1
    2 2
    2 2
    3 1
    3 2
    4 1
    4 2
    4 2
    5 1
    5 2
    6 1
    6 2
    6 2

    The repeating of one field in every 5 creates the extra 12. You can see from the wee table that this give a 2,3,2,3,2,3 fields sequence. While PAL has the problem of innacurate pitch NTSC has a problem of temporal artifacts with "judder" in pans from the added repeat field.

    3: Very helpful.

    4: It is agreed. Arcam DV88plus is shipping as we speak with this as standard. There are already many units that are hacked to enable this.

    Hope this is use,

    Gordon
     
  3. James45

    James45
    Standard Member

    Joined:
    Sep 21, 2002
    Messages:
    2,844
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    59
    Location:
    Taking Care of Business
    Ratings:
    +0
    this should really be moved to DVD players or prog sacn

    but while it's here what methods can you use to output a progressive scan (ie RGB SCART? YUV? S-VIDEO?) and do you need a special display or could you feed it to a normal television? I am interested in moving onto progressive scan as the benefits appear obvious although I know very little on the subject.
     
  4. Mr.D

    Mr.D
    Well-known Member

    Joined:
    Jul 14, 2000
    Messages:
    11,061
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    133
    Ratings:
    +1,149
    Kinda helpful.

    However most TV manufacturers when they talk about NTSC compatability are referring to the colour decoder in the set being able to handel an NTSC colour signal. This is only applicable as an indicator if you are using a composite type signal ( composite or s-video).

    When you use an RGB signal through a scart lead (which is incidentally about the best input type you'll get on your average TV) its not really relevant to talk about PAL/NTSC as RGB doesn't utilise a composite colour carrier which PAL and NTSC are standards of. The actual format of the image is still an issue : ie 625/50 for "PAL" 525/60 for "NTSC" and this area may be a source of incompatabilty on certain TVs.

    However in practice an awful lot of TVs out there that don't state NTSC compatability and indeed will deliver a black and white image with an NTSC signal will quite happily display the "NTSC" formatted material in colour with a stable picture if you feed it in as RGB rather than composite. Caveat: its not every TV but if it has a scart port that accepts RGB more often than not it will display your NTSC formatted material just fine or with minor annoyances (AKB lines for example) rather than not at all.
     
  5. Gordon @ Convergent AV

    Gordon @ Convergent AV
    Distinguished Member AVForums Sponsor

    Joined:
    Jul 13, 2000
    Messages:
    14,013
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Living in Surrey, covering UK!
    Ratings:
    +2,809
    Practice makes perfect they say and I'm giving a talk about this at the Scottish HiFi and Home Cinema show in two weeks so I better practice...

    Progressive scan can be sent in a few methods.
    Analogue RGB and it's derivatives of RGsB,RGBS,RGBHV etc but not from a scart socket.
    Analogue Y-U-V or YPrPb as they are commonly marked on display devices.
    Also in digital form but we wont talk about that as you're not likely to come across it unless you want to give me alot of dosh for some serious broadcast kit.

    So no s-video or composite....

    Yes you need a special display. First of all it must have the bandwidth capabilities to accept 32kHz (or basically twice the resolution of normal interlaced). The trouble of course is that just because a unit can accept such a signal doesn't mean it can actually display it accurately. You may find that some displays, when fed a progressive signal, will have geometry problems, softness, overscan issues or all of the above.

    The resolution of PAL and NTSC progresssive are different. NTSC is very close to VGA standards so there are many commercial displays that will accept it. PAL is not close to anything though and you really need to confirm with manufacturer that the 576P(625P) format is accepted.

    When choosing a device that outputs progressively you ideally want to make sure it can detect the 2:3 sequence of NTSC and the 2:2 sequence of PAL telecine(the term for turning film in to video). If a device doesn't have this ability the chances are you're going to see quite a few nasty de-interlacing artefacts in the progressive image. Once you've found a shortlist of devcices that meet these requirements test them on your chosen display and enjoy, hopefully a nice image.

    There are other things to look out for on progressive devices but that'll do for now.


    I suggest a moderator moves this to a different location......

    Gordon
     
  6. Couch Potato

    Couch Potato
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Does this mean the yoghourt pot's making an appearance ;)

    Steve
     
  7. LV426

    LV426
    Administrator Staff Member

    Joined:
    Jul 14, 2000
    Messages:
    12,845
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Somewhere in South Yorkshire
    Ratings:
    +5,078
    Just to restate and clarify what Keith says:

    Using RGB is not a guaranteed solution. The two major factors that distinguish NTSC and PAL are

    1: The line and frame rate, as already discussed
    2: The method of encoding colour into the image.

    Using RGB gets over any incompatibility in (2). However, to display a stable image, the display device has to be capable of displaying the 525 line 60hz structure of NTSC. The vast majority can. But some (usually older, and more prevalent in some brands than others - Philips and JVC come to mind) cannot.
     
  8. bxd

    bxd
    Active Member

    Joined:
    Oct 17, 2001
    Messages:
    1,482
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    66
    Location:
    Southampton
    Ratings:
    +136
    Gordon,

    Do you have any idea of what type of 'output' socket (scart or rca) that the industry will use for progressive pal ?

    My old Sony 1031 projector can accept a rgbs progressive signal on it's scart input socket so I don't suppose that there is any reason why you can't use a progressive output from a dvd player via it's scart socket.

    Brian
     
  9. Gordon @ Convergent AV

    Gordon @ Convergent AV
    Distinguished Member AVForums Sponsor

    Joined:
    Jul 13, 2000
    Messages:
    14,013
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Living in Surrey, covering UK!
    Ratings:
    +2,809
    It's going to be coming out as a YPrPb signal through either RCA or BNC's I'd imagine. Probably the former.

    You'll need a transcoder to turn it in to RGBs colour space.

    Gordon
     
  10. They

    They
    Standard Member

    Joined:
    Sep 10, 2002
    Messages:
    171
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    16
    Location:
    Bristol
    Ratings:
    +0
    The blended frames (actually fields) are the result of very poor standards conversion between 525/60 (USA) and 625/50 (UK). These are usually done in the USA by people who don't give a damn about quality and purchased over here by people who give less of a damn about quality!

    Americans don't see these poor images, but do suffer the 3:2 pulldown judder which is caused by the conversion from 24fps film to 60fields (30fps) NTSC video.

    Excellent quality standards conversion has been available for many years, but there is an attitude problem in the post production and broadcast industries, so we end up with the appalling quality on USA shows shown in PAL territories and this is componded by low bit rate digital TV broadcasting.

    It's all down hill from here I'm afraid!
     

Share This Page

Loading...