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  1. I have a home movie recorded on VHS in 2000. When I watch it on my Sharp 46" LCD, the image fills the entire screen, i.e. no black bars are present. I did a quick search and found that VHS has a resolution of 480x333, which translates to an aspect ratio of 1.441:1. My LCD TV has a screen resolution of 1680x1050, which translates into an aspect ratio of 1.6:1. How is it that a VHS recorded on a camcorder in 2000 has a perfect fit resolution to a modern LCD TV with a 16:10 aspect ratio? Is my TV performing some sort of autoscaling on the image? I know 16:10 is standard for video recording on current electronics, but I can't imagine that was the standard for VHS in 2000, was it?

    A related question: I had the tape in question captured and recorded to a DVD by a company that specializes in that. The DVD came back with the following mediainfo:

    Code:
    Width                                    : 720 pixels
    Height                                   : 480 pixels
    Display aspect ratio                     : 4:3
    Oddly it says the aspect ratio is 4:3 (1.33:1), but 720/480 = 1.5. Is that correct?

    When played on a regular DVD player on the same TV, this DVD has black bars on the left and right, which is exactly what I would expect from that resolution.

    So what is going on here? Did the original VHS recording have a 16:10 aspect ratio and the captured DVD scaled that down to a 4:3, or is 4:3 the native resolution and my TV for some reason is expanding the VHS picture to completely fill the screen (but not the DVD)?
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  2. I'm a Super Moderator johns0's Avatar
    Join Date: Jun 2002
    Location: canada
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    I doubt your lcd tv has that resolution,more like 1920x1080 and the picture is being zoomed so you don't see any borders,when you play it on your dvd player it plays in the correct aspect.
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  3. Nevermind, I just read my TV's manual and realized it was stretching the original 4:3 image to fit the screen. I changed the view mode and now the VHS image looks the same as the DVD.
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  4. Member Cornucopia's Avatar
    Join Date: Oct 2001
    Location: Deep in the Heart of Texas
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    Let's get this all clear, because I don't want to have other newbies referring to this when bringing up similar questions.

    The facts:

    1. VHS is Analog. Analog recordings do NOT have "resolution" in the same manner that Digital recordings do. They are of theoretically "infinite bandwidth", but practically speaking (because of falloff), VHS, as a low quality consumer tape playback medium, has a good deal less than the standard NTSC alloted bandwidth of 6MHz. How this equates to an equivalent digital resolution varies, but I think it is safe to say that, on a good day, VHS is like 352x480 with a Pixel Aspect Ratio of ~20:11 (and thus a DAR of 4:3). Why not standard D1 (720x480 or 704x480) you ask? Because VHS blurs everything so much that sampling at a better resolution doesn't get you any distinct quality improvement.

    2. Where the heck you ever got 480x333, I don't know. But it sure isn't a standard resolution, and only a fool would try to encode to something of LOWER resolution than VHS already is, as well as use an ODD (numbered), non-mod16 resolution, particularly on the vertical (where there should always be an EVEN number of lines). But what this number signifies might not even be the actual stored resolution, but just something that the current player you are using is throwing out there. Very suspect.

    3. 720x480 can often be 4:3 but it can also often be 16:9, it all depends on what the PAR is. The formula you should be working with is
    Code:
    DAR = PAR * Horizontal Rez / Vertical Rez (aka SAR)
    In the mediainfo readout above, your DAR = 4:3 (aka 1.33:1) and your SAR = 720/480 = 1.5, but measuring SAR doesn't count for much (since multiple pairs of resolutions can have that same SAR). It is the DAR and the PAR that you want to focus on. In the above instance, your PAR would calculate to 10:11 (or 8/9 depending upon how you calculate your D1), which happens to be a standard NTSC PAR for 4:3 images.

    4. You don't say what model your Sharp 46" display is, but going direct to Sharp's website and bringing up 46" LCD TVs all show 1920x1080 as the resolution, NOT 1680x1050. Again, this is an ODD-numbered and unusual figure for a display and I am dubious as to where you even got this number.
    There are a few monitors made that are 16:10 (mostly meant for PC usage), but the overwhelmingly large majority of recent consumer TV models are 16:9.

    5. How a supposed 4:3 DAR image fits on a supposed 16:9 or 16:10 DAR screen will vary DEPENDING UPON HOW YOU SET IT. There are a few main ways - Leave as is and Letterbox/Pillarbox with (black) padding, Zoom & retain image shape but cropping the part of the image in excess of the display's DAR (in this case that would be part of the top & bottom), or Anamorphic stretching of the Horizontal while leaving the vertical alone and thus filling the screen. This will, however, give you an image where circles are now oblong and squares are rectangles (both fatter than in reality). Fancier TVs have a few smarter variations on those, but that is all the choice you'll have. It's the old "square peg, round hole" conundrum. Clearly, your TV is set (by you) to do the last option and stretch things. And that's your choice.

    6. Alternately, your DVD player has been set to NOT do that same stretch, but is choosing rather the first option of letterboxing/pillarboxing.

    7. There is nothing odd about what is going on with the image. You just aren't yet fully aware of how this all works together, nor how to best get the visual format you desire.

    Sorry, johns0, but I just had to expand on this. Seen too many of these type of posts lately...

    Scott

    <edit>Ahhh, great things those manuals. </edit>
    "When will the rhetorical questions end?!" - George Carlin
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  5. Member turk690's Avatar
    Join Date: Jul 2003
    Location: ON, Canada
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    This thread should be a sticky. Most people get along with the resolution thing on the assumption that pixels are always square. Where confusion arises is when they are told pixels anywhere can have other ARs. Years ago, when someone thinks they get it, I proudly point to an ancient Sony plasma TV I had that had a DAR of 1024x1024, and how, properly setup, it displays all of the other resolutions correctly.
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  6. Originally Posted by Cornucopia View Post
    Where the heck you ever got 480x333, I don't know.
    I'm guessing one of those weirdos who state the vertical resolution first. Of course, that's still an odd measurement for the other direction.
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  7. OK, it looks like I got owned on this one. Oh well, at least I learned something. To address some of the specific questions raised:

    Originally Posted by cornucopia
    Where the heck you ever got 480x333, I don't know.
    I don't remember where exactly I found that. I did a quick google search and assumed the issue was old enough that it wouldn't be disputed anymore and one of the first results would be correct. Here is a sample from wikipedia:

    Originally Posted by wikipedia
    VHS is roughly equivalent to 333480 pixels luma and 40480 chroma resolutions (333480 pixels=159,840 pixels or 0.16MP (1/6 of a MegaPixel))
    taken from:

    http://en.wikipedia.org/wiki/VHS

    Originally Posted by cornucopia
    You don't say what model your Sharp 46" display is, but going direct to Sharp's website and bringing up 46" LCD TVs all show 1920x1080 as the resolution, NOT 1680x1050.
    Correct, I was thinking of my old 20" LCD monitor's resolution for some reason.

    Very informative post. Maybe that information should be a sticky. It certainly would have answered all of my questions and prevented me from making this post.
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