Discussion in 'Displays' started by John_Q*, Jul 4, 2003.

  1. John_Q*

    John_Q* Extra

    May 25, 2003
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    Hi guys,
    I just had a couple terminology questions, since there is tons of "shop talk" around here. I can't seem to find an easy source for these sort of answers.

    1) What is 3:2 pulldown?

    2) What is convergence?

    3) Where do you buy the AVIA calibration program?

    Thanks in advance for any answers!
  2. Steve Schaffer

    Steve Schaffer Producer

    Apr 15, 1999
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    1) Film is shot at 24 frames per second, video at 30 fps.
    When performing de-interlacing (line doubling) the difference between the two frame rates can result in "combing" or jagged edges in the picture. 3:2 pulldown for film-based sources eliminates this problem.

    2) Most rptvs and a few front projectors use 3 CRTs to produce the picture: red, green, and blue.

    In the case of an rptv, these crts are in the bottom of the set pointed up at a large mirror which in turn bounces the picture onto the backside of the screen you're looking at. A front projector projects directly onto a screen across the room, just as a movie film projector does.

    In both cases, the 3 individual pictures must all hit the screen in exactly the same place in order to not have fringes of color at the edges of objects being displayed.

    In other words, the 3 pictures must converge in one place.

    3) AVIA is not a computer program. It is a dvd with test patterns for video adjustment and test tones for audio calibration, along with comprehensive voice-over instructions on their use. It is hard to find at most local stores that sell dvds, but easily found at online dvd retailers like DVDEmpire, Laser's Edge, Amazon.com.
  3. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

    Mar 16, 2000
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    Calgary, Alberta
    Real Name:
    Michael Chen

    Avia is purchased or order from any retail outlet that sells DVD's or from the NET.

    Convergence WRT projection crt based TV's is getting the red and green and blue images to all be centered in the same location to form an image.

    3:2 pulldown is used to properly convert film which runs at 24 frames per second to video which is 30 FPS. More can be found on this subject at secrets of home theater and hi fidelity web site.

  4. Craig Robertson

    Craig Robertson Supporting Actor

    May 12, 1999
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