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  1. Mountains of gear vaporeon800's Avatar
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    Apr 2001
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    First a blow-up of a capture with the NTSC line numbers identified. Because they are numbered sequentially by field, they alternate when viewed as a full raster.

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    The second field begins with line 264, so if you subtract 263 from its line numbers you get the number relative to its start (i.e. line 284 is line 21 of the second field). The first 9 lines of each field contain "equalization pulses and broad pulses" rather than vertical interval video.

    .........VCR -> DPS..........VCR -> DMR-ES15 -> DPS...VCR -> D-KR4 -> DPS..
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    I thought it was interesting to "see" what Macrovision looks like (though the ColorStripe version also occupies the horizontal sync area). Apparently you can take a look at this using the vertical hold controls on older CRTs as well, and one guy on YouTube found an LCD that allows a wide vertical adjustment range.

    You can see what the two DVD recorders do when passing signals through to the outputs:
    • black out everything before line 23
    • re-add closed captions from the source, if present
    • generate a new Macrovision signal if one was detected
    The chat line commercial is from a 2003 recording. The station likely used a digital source with only 480 active lines. The image begins at line 23 (adhering to SMPTE RP 202).

    The VHS camcorder that my family used in the '90s doesn't have anything in the VBI. The image starts with the half-line on line 284 followed by the first full line on line 22. Since line 21 was reserved in 1976, other analog camcorders probably do the same thing.

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    The Diamond VC500 USB stick starts capturing at line 22. Unlike the DVD recorders' passthrough, the DPS-470AV frame sync's composite output leaves lines 22 and 285 intact. It smooths the picture, though. (The second image is overblown because of the VC500's reaction to Macrovision.)

    ..VCR -> DPS -> VC500..........VCR -> VC500........
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  2. Member 2Bdecided's Avatar
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    Interesting stuff.

    You could try a broadcast monitor. Put it into "Pulse Cross", or "H and V Delay" mode.

    See here...
    http://www.davidstringer.info/training/how_television_works.htm
    ...search the page for pulse cross to find a picture of what you'll get.

    These things used to cost a fortune, but now the SD-only versions sometimes turn up for peanuts.

    Cheers,
    David.

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  3. Originally Posted by 2Bdecided View Post
    Interesting stuff.

    You could try a broadcast monitor. Put it into "Pulse Cross", or "H and V Delay" mode.

    See here...
    http://www.davidstringer.info/training/how_television_works.htm
    ...search the page for pulse cross to find a picture of what you'll get.

    These things used to cost a fortune, but now the SD-only versions sometimes turn up for peanuts.

    Cheers,
    David.



    Is there any cheap monitor that can do this? Is there any video input card for the PC that can do this (cheap or otherwise)
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  4. Mountains of gear vaporeon800's Avatar
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    Originally Posted by Videogamer555 View Post
    Is there any video input card for the PC that can do this (cheap or otherwise)
    For what purpose?

    Old capture cards with a specific chip can use special Linux drivers to write raw ADC data. This is all terminal stuff, and currently the data can't be decoded to a stable color image. Perhaps you're interested in enhancing the software?

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  5. Member
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    Some of the Osprey cards can show the VBI as a waveform.
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