Letterbox Mode On Digifusion FVRT100

Discussion in 'Digital TV & Video Players & Recorders' started by oilman, Nov 4, 2005.

  1. oilman


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    Hi guys,

    I am new to this Forum, and I did search for details on my issue, but wasn't able to find much so I apologise in advance if this has been adequately covered elsewhere.

    I have a digifusion FVRT100, and it was recently updated (last weekend) with the latest version of software. The previous version of software had a problem whereby it did not properly display 16:9 broadcasts properly for all TV channels (especuially ITV 2/3), squashing them in a 4:3 frame.

    From web searches (and admission by Digifusion), this was a well known issue. The recent update solved this problem, but introduced a much more irritating problem inasmuch as letterbox mode on a 4:3 set is now completely messed up.

    On some channels, the picture is shown with a large bar at the bottom, and none at the top i.e.the picture is offset in the vertical plane. This looks really stupid (the picture is not even square because of the rounded edges of the TV at the top). What is even more irritating is that this worked ok before the recent update!!

    However, if you look at BBC NEWS 24 say, which always transmits in true widescreen, the picture is properly centred vertically on the screen (large bars to and bottom).

    I think this letterbox problem is occuring because of the insistence of some broadcasters to prefer the irritating compromise 14:9 format i.e they say that users of a 4:3 set should view in 14:9 not 16:9 even though the broadcast is actually true 16:9. This is enable by use of ARCs (aspect ratio codes - see below).

    For those not familiar with the digital broadcast codes, I attach a brief summary that describes what I am trying to say about 14: 9 format on digital terrestrial TV. It is the protection code that causes confusion (see website http://bitbucket.co.uk/work/aspect_ratios.htmlfor more details).

    I strongly suspect the Digifusion ltterbox problems occur when the Protection ARC is code B (The middle 14/16ths of the active picture is protected. So a 16:9 active picture, with this protection, will have thin black bars top and bottom, and some cut off this sides, when put in a 4:3 raster). This would not be such an issue if the display was not off-centre!

    On many digital boxes, you can simply set 14:9 or 16:9 letterbox manually.

    Digifusion - Why not let the user decide what mode he/she wants!!! Even if you don't do this please correct the 14:9 letterbox display issue asap!

    Aspect ratio codes
    As can be imagined, conversations about aspect ratios can get very confusing. So there is a standard(ish) set of codes to try to describe what you're on about.

    Aspect ratio format description codes take the form xxAyyP. In no particular order;

    xx - The Active Image Aspect Ratio*. That is, the aspect ratio of the colourful moving bit, ignoring any black bars that might be included in the picture.

    yy - The Raster Aspect ratio*. This means the aspect ratio that the final image (black bars and all) should be viewed at to avoid distortion.

    A - The Display Format. Describes how the picture is to be mutilated;
    P - pillarbox (bars added at the sides)
    L - letterbox (bars added at the top and bottom)
    F - fullframe (no bars added, nothing changed - the active picture fills
    the raster)
    M - mixed (a nightmare world of pain and confusion)

    P - Indicates Protection for conversion. This describes which parts of the picture are essential, and should be protected from removal if the image is manipulated;
    A - 16:9. The entire active picture is protected (only applies to 16:9
    active pictures.) So if you try to put it into a 4:3 raster, you'll end up
    with black bars at the top and bottom.

    B - 14:9. The middle 14/16ths of the active picture is protected.
    So a 16:9 active picture, with this protection, will have thin black bars
    top and bottom, and some cut off this sides, when put in a 4:3 raster.

    C - 12:9 (4:3) The central 12/16ths of active picture is protected.
    This results in a center cut out.
    N - Nothing protected

    So, in summary, the first part (xxAyy) describes what you're starting with. The last letter (P) lets subsequent users know how the image can be converted to other formats.

    * - xx & yy are the first two digits of the aspect ratio code; 16 (for 16:9) 14 (for 14:9) or 12 (for 12:9 = 4:3.)

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