AJA FS2 - Manual (Page 93)

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93 FS2 Installation and Operation Manual — VIDEO 1 and VIDEO 2 Menu Groups
7 Downconvert
Mode This parameter selects the type of Downconversion performed by the Video
Processor on the selected HD source input. See the following Downconvert
Illustrations for Downconversion examples. This parameter is in effect only when the
input is HD (720p, 1080i, or 1080p) and the output format is SD (525i or 625i), or when
the input is 2K (2048 x 1080)and the output is HD (720p, 1080i, or 1080p). When
downconverting from 2K, the selections do not precisely describe the resulting
picture. For example, 14x9 is not precisely 14x9. However, picture scaling is such that
the visual effect closely resembles an HD-to-SD downconvert.
Notes: Active Format Description (AFD) codes are carried in the vertical ancillary
(VANC) portion of HD SDI video signals, specified in SMPTE 2016 as follows:
“AFD information is intended to guide DTV receivers and/or intermediate
professional video equipment regarding the display of video of one aspect ratio
on a display of another aspect ratio.”
In the FS2 Downconverter, the AFD code on the video input can be used to
guide the Downconverter in choosing which mode to use to best display the
important content of the input 16:9 HD video on the 4:3 SD output. For
example, if the input AFD code is 10 (Full Frame), it means that the input video
has important picture information throughout the full 16:9 frame, so the
Downconverter should use Letterbox mode to be sure none of the content is
cropped off. An AFD code of 9 (Pillarbox) says that the input video only has
content within the center 4:3 area of the picture (usually because it originally
came from an Upconverted SD signal) so the Downconverter Crop mode would
be the best choice. There are 16 possible HD AFD codes, of which 8 are in
common use. The FS2 does not process or use SD AFD codes.
FS2 AFD processing (passing, removing, and re-inserting) occurs based on the
setting of parameters 7, 5.4, 16.1, and 16.2.
Auto AFD mode fully defines the size, position, and aspect ratio of the output
raster. Thus, when in Auto AFD mode (Output Format set to an SD format, with
an HD video input, and Downconvert Mode set to Auto AFD), any Custom Size/Pos
settings are ignored, and those menus (13.0 - 13.8) are hidden. Likewise, when
in Auto AFD mode, any Region Of Interest settings are ignored, and those menus
(14.0 - 14.4) are hidden.
7 Downconvert Mode Selections Selection Descriptions
Crop (default)
Anamorphic
14:9
Auto AFD
Letterbox
Image is cropped to fit new screen size.
HD image is converted to full-screen SD with a 16x9 aspect ratio
(anamorphic).
Image is reduced slightly with aspect ratio preserved. Black is added top
and bottom, and the left and right sides are cropped.
Automatically selects the best Downconvert mode based on the input
video's Active Format Description (AFD) code. If the input video is not
carrying an AFD VANC code, the Downconverter defaults to the
mode specified in parameter menu 16.3 Downconvert AFD Default.
Image is reduced with black top and bottom added to image area, with
the aspect ratio preserved.