The aspect ratio describes the relationship of screen width to screen height. Standard TV signals are based on an aspect ratio of 4:3 (four units wide by three units high). HDTV signals are based on an aspect ratio of 16:9, making the image 33 percent wider than a normal TV, and enabling you to view TV and movies as if you were watching them in a theater.
In addition, many DVD movies look better on the widescreen display, because most of the movies made in the last 50 years were filmed in an aspect ratio of either 1.85:1 (very close to 16:9, which is equal to 1.78:1) or 2.35:1 (even wider than 16:9).
Variable aspect ratio support enables the scaling of 4:3 and anamorphic video so that the image fills the screen.
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