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46
Selenio X100
Installation and Operation Manual
General Information on ARC and AFD
AFD (Active Format Description)
Active Format Description (AFD) transmits data in the VANC portion of the SDI signal,
enabling both 4:3 and 16:9 television monitors to optimally present video with preset ARC
and safe area information. Without AFD, converted video may appear distorted or "cut off"
when it appears on different monitors. The Selenio X100 can encode or decode AFD; it can
also encode or decode earlier Video Index (VI) and Wide Screen Signaling (WSS) formats.
AFD/ARC Alignment
When you use AFD to select your aspect ratio, the X100 ensures that the AFD codes and
associated image will remain in sync. For example, during a hotswitch, the new ARC will
only be applied to the new image. There are a few cases which could cause AFD/ARC
misalignment:
The ARC applied is reducing the image vertically such that the new image is less than
60% of the original image.
The output standard is set to either 1080p/23.98 or 1080p/29.97.
Figure 3-8
shows two comparisons of a signal that is encoded with AFD and without AFD.
SD-SDI 4:3
Up
Full frame
SD-SDI 4:3
Up
16:9 Letterbox
Figure 3-8 AFD/Non-AFD Comparisons
HD-SDI 16:9
Down
Pillarbox
HD 16:9
Using active format
description (best result)
Full frame
Without active format description
Postage stamp
SD-SDI 4:3
Postage stamp
Full frame
Using active format
description, the original image
information is maintained
throughout the entire
conversion , creating the best
possible viewing area .
(undesirable result)
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