Imagine Selenio X50, Installation And Operation Manual, Page: 50 / 136

Chapter 3
Controls
36
Examples of Automatic Aspect Ratio Conversion
You can enable automatic ARC controls by setting the ARC Preset parameter to AFD ,
AFD-ALTR , VI , VI-ALTR , WSS, or WSS-ALTR . When you set ARC Preset to AFD and the
upstream video has AFD code embedded in it, the system will present the video signal in the
appropriate aspect ratio, and generate new downstream AFD code accordingly. (You can
confirm that AFD is available in the input signal by checking the
AFD Present parameter.)
For example, in upconversion mode, an upstream signal with an AFD code of 1000
indicates the output will be a full frame 4:3 image. The X50 creates a 4:3 Pillar Box arc,
and the output HD image becomes a 4:3 pillar box. The resulting AFD code becomes 1001
(4:3 center).
In another example, the X50 is in downconversion mode. The upstream signal has AFD
code
1111, indicating a 16:9 ratio with alternative 4:3 center. If you set the ARC Preset
parameter to AFD , the X50 creates an output of 16:9 letter box and the resulting AFD code
becomes 1111 . If you set ARC Preset to AFD-ALTR , system does a center cut ARC, the
output becomes 4:3 full, and the resulting AFD code becomes 1000 . This result is
commonly used in the USA.
Figure 3-10 on page 37 to Figure 3-13 on page 40 show all of the conversion patterns.
In the event that the current ARC is controlled by AFD, VI or WSS, and this data disappears
from the input signal, the X50 provides you with two options:

Retain the current aspect ratio as set by the last AFD, VI, or WSS data.

Reset to the aspect ratio settings that were in use before the AFD, VI, or WSS data took
control
The Auto ARC Reset parameter controls this feature. Select Yes to have the module reset
to older values in the event of loss of data; select No (the default) to retain the current ARC.
Some AFD code “encourages” cropping out some of the active video area. To prevent this,
set
AFD Crop Enable to Disable .
The Out Aspect Ratio parameter controls the output aspect ratio of the SD signal, and it
will affect how the AFD performs the automatic conversion. (It is assumed that an SD signal
may be either 4:3 or 16:9, but an HD signal will always have a 16:9 ratio.) The default value
of the
Out Aspect Ratio parameter is 4:3.
Output AFD,
VI and WSS
You can insert AFD, VI and WSS data into an output video stream either manually or
automatically. This function is controlled by the
AFD Control, VI Control, and WSS
Control parameters. If you are using VI according to the SMPTE proposed RP-186+
standard as of January 11, 2007, you must ensure you have enabled the standard by setting
Enable AFD in VI , (located in the same path as the other output control).
The AFD embedder attempts to embed packets into the specified line after the existing
VANC packets in the video stream. If the existing packets occupy more than 1260 pixels, the
AFD embedding will not occur.