4.2

The ratio between an image’s width and
height. For example, Standard-definition (SD)
video typically has an aspect ratio of 4:3. High-
definition (HD) video typically has an aspect
ratio of 16:9. If SD video is played on an HD
display, the image is either stretched or
appended with black borders on left and right
sides (pillarboxes). If HD video is played on an
SD display, the image will be squeezed or
black borders will appear at the top and
bottom (letterboxes).
display aspect ratio (DAR)