VideoHelp Forum

Our website is made possible by displaying online advertisements to our visitors. Consider supporting us by disable your adblocker or try DVDFab DRM and remove iTunes movie & music protection! :)
+ Reply to Thread
Results 1 to 5 of 5
Thread
  1. Hi Chaps, I'm trying to find a way to generate some test patterns so I can test a Teletext and WSS detector. VBI lines 21-23.

    Yes, I know its a bit the way of the dodo, but nevertheless, I need to do it.

    Any thoughts on how I can do this?

    Thanks in advance

    Neil
    Quote Quote  
  2. Member Cornucopia's Avatar
    Join Date
    Oct 2001
    Location
    Deep in the Heart of Texas
    Search PM
    Photoshop/illustrator, or similar, including FOSS alternatives. Use grids to help compose exactly.
    Create full-frame & wide frame versions. Label them both on and offscreen.
    Output each permutation over HDMI to a recorder that can give you the option to record in WS or not (which should generate WSS when appropriate on playback), so you have all possible combinations.

    Or just check with the makers of the WSS equipment, as I bet they encounter this a lot and could probably hook you up to where you can buy footage.

    Scott

    *Can't comment on the teletext part, as I don't live in a country that uses that.
    Quote Quote  
  3. Member
    Join Date
    Aug 2010
    Location
    San Francisco, California
    Search PM
    Cheapest: look for videocassette recordings which contain these signals.
    Spendiest: buy a signal generator capable of these standards, such as http://www.astrodesign.co.jp/english/product/vg-884.
    Quote Quote  
  4. Originally Posted by themoog View Post
    Hi Chaps, I'm trying to find a way to generate some test patterns so I can test a Teletext and WSS detector. VBI lines 21-23.
    What is your hardware? VBI lines are not visible (except second half of line 23), WSS can be encoded in regular video but 21 and 22 (and other VBI lines) require dedicated video HW.

    How to generate them - easiest and IMHO one of best methods (for static) is Excel (or any similar spreadsheet software - i've generated some test signals with librecalc) - 720 samples is can be easily generated manually, TXT signal is more complex but you can create them also in similar way.
    Of course you can use dedicated signal generators - i assume Tektronix TG700 can be bought nowadays quite cheaply.

    Of course some language like C or perhaps even Python may be very helpful (especially for TXT)...

    Everything depends from you.

    ---
    after some time - you are lucky - seem you should be able to use Raspberry Pi as signal source thus all tasks like TXT or WSS generation should be easily reachable

    https://github.com/ali1234/raspi-teletext

    Originally Posted by JVRaines View Post
    Cheapest: look for videocassette recordings which contain these signals.
    Common VCR's are too limited to provide reliable WST signal... (jitter, bandiwdth etc), WSS is doable but WSS can be encoded within regular 576 video so any SD media player can be used.
    Last edited by pandy; 21st Jul 2018 at 09:56.
    Quote Quote  
  5. Member
    Join Date
    Feb 2018
    Location
    Florida
    Search PM
    If you are still interested, I have a unit which generates WSS and CGMS. Anything that is on line 20 field one and also Extended Data Services packets on line 21, field 2. Close Caption on line 21 field 1, is left unchanged from the input data stream.

    Are you working with NTSC or PAL standard?
    Last edited by videofilter; 12th Sep 2018 at 13:05.
    Quote Quote  



Similar Threads