How can an NTSC video signal be 16:9 without masking or cropping?

Question

Edit - That's what I thought, but I have a device right here (a new camcorder) that has a 16:9 mode, when sending composite video to the video input of a plasma, if the plasma is set to 16:9 it fills the screen. Change display to 4:3, and it's horizontally compressed (as I would expect). Any clues?

Answer 1

It can't be that way. NTSC is 4:3, only.

in order to "fit" it into 16:9, you must crop, mask, "letterbox", or horizontally stretch (distort) it. Of those 4, "letterboxing" is the preferrable method, or letterboxing with a partial horizontal crop.

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Answer 2

Even though the signal from the camcorder is "NTSC" it does not fit the standard specifications. The result you describe is consistant with using horizontal astigmatism to fit a wider screen into the 4 x 3 window. The difficulty with that method is that the NTSC picture resolution (as determined by the 4.5 MHz maximum frequency of the picture signal) is not improved. Thus, the wider picture is made up of the same number of horizontal pixels - making the picture more "grainy". However, if the camcorder has other forms of signal output which can have a higher horizontal frequency, then a totally pleasing wide screen picture is possible. Note that we are not talking about an "enhanced" NTSC because the color sync frequency limits the maximum horizontal frequency and thus the resolution.

In any case when stuck with the NTSC format, a letterbox is even less desirable than a "horizontal stretch" because the horizontal resolution for both is the same and in the letterbox format, the vertical resolution is reduced by committing fewer picture lines to the actual picture (some fraction of the picture lines are lost making the black bars at the top and bottom of the picture).

Answer 3

Guys, think about it - NTSC specifys the horizontal and vertical scan frequencys, but not actually the pixel clock. In fact, there is no pixel clock. The number of pixels in a horizontal scan line is basically by agreement, based on a 4:3 aspect ratio. Therefore, if by convention you agree that your pixels are from a 16:9 source rather than a 4:3 source, there is no problem whatsoever. And the result is, horizontal (but not vertical) resolution is improved.

To test this, you can input your camcorder signal to an older basic NTSC TV or monitor. Unless the 3.58MHz color burst signal, which CAN act as a source for a pixel clock, screws things up (in which case your plasma is able to account for it), your picture should be normal except for appearing horizontally compressed.