Mentor XL
4.2.3
Digital Video – Active Format Description (AFD)
Active Format Description (AFD) is a standard set of codes that can be sent in the video signal that
carries information about their aspect ratio and active picture characteristics. It is used by television
broadcasters to enable both 4:3 and 16:9 television sets to optimally present pictures transmitted in
either format. It is also used by broadcasters to dynamically control how down-conversion
equipment formats widescreen 16:9 pictures for 4:3 displays.
Three menu entries allow the AFD feature to be turned on or off, the insertion line to be selected
(on Fields 1 & 2) and the AFD code to be set according to the table below. Note that the precise
interpretation of the code may depend on the standards authority being studied. The code may be
represented as decimal or 4 bit binary.
Decimal Binary Summary
2
0010
16:9 top of frame
3
0011
14:9 top of frame
4
0100
16:9 vertically centred
8
1000
4:3 same as frame
9
1001
4:3 same as frame
10
1010
16:9 vertically centred
11
1011
14:9 vertically centred
13
1101
4:3 – alternate 14:9 centre
14
1110
16:9 - alternate 14:9 centre
15
1111
16:9: alternate 4:3 centre
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