Overscan Scale - (c) 2003 r6d2

Definitions
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Frame size - The size in pixels of a given frame. For instance, 720x480. Some times this concept is confused with resolution, defined below.

Resolution - The actual information we can distinguish in an image. Analog NTSC 4:3 TVs are typically capable of delivering 427 horizontal lines of resolution.

What is this?
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This is a NTSC SVCD image file which displays a given pattern on 7 different frame sizes (352x240, 352x480, 480x480, 528x480, 544x480, 704x480 and 720x480). Each of them is a separate chapter of the SVCD stream. The pattern has a scale which you can use to measure/adjust the overscan of your TVs.

An horizontal resolution measure pattern is also incorporated. Vertical lines are drawn "1 pixel wide and 1 pixel apart" for resolution of 1/1 DVD, 3/4 DVD, 2/3 DVD (SVCD), 1/2 DVD (CVD, VCD).


Mode of use
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1. Burn the image on a CD-R/WR media.

2. Insert on DVD player and turn on TV.

3. The first VCD sequence is shown. The next resolution will be shown about 4 seconds. Use the pause button to hold the image still on a particular res.

Measuring Overscan
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The green thinest lines are units. The thick lines are tens. For instance, if the first visible line from the top is the corresponding to 6% and the first visible from the bottom is 5%, your TV has a vertical overscan of 5% (choose the mimimum of each dimension to be safe with tools like FACAR for DVD2SVCD).

Typical 4:3 TVs have an overscan of about 5% +/- 1%. The pattern has a blue 5% square to guide you.

Measuring Horizontal Resolution
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NTSC's horizontal resolution can only be measured empirically. If for any particular frame size you can distinguish the white vertical lines associated with that frame size., your TV is capable of giving you an horizontal res equivalent to that of the frame size. If you only see the previous frame size's white lines, your TV is only capable of giving you that previous horizontal resolution.

Typical 4:3 TVs give you usually 400-500 vertical lines of resolution, which is called "horizontal resolution".



Known limitations:

- VCD resolution is quite blurry for the overscan scale, the others are much better. However, VCD and CVD will surely have exactly the same overscan.
