Grass Valley Switcher Products - Manual (Page 144)

144 Switcher Products — Protocols Manual
Section 6 — Still Store Image File Format
Output Crop and Position
Cropping determines what portion of the image is output by the still store.
Positioning relocates the image relative to screen center. These parameters
do not affect the contents of the image data file. They only affect how the
still store presents the image when loaded to an output.
Values are in screen units relative to screen center. Screen units are based on
the “clean aperture” as defined in SMPTE RP-187.
The still store captures and outputs a production aperture by default. The
values shown in
Table 127 place the crop edges at the points defined by
SMPTE as the production aperture, essentially disabling the crop.
The specified values will set the crop exactly at the production aperture,
but this is the middle of the shaped edge. For an uncropped image, crops
need to be set outside these values.
Note 16:9 mode is not currently supported for SD formats. All SD images, regard-
less of their actual aspect ratio should use 4:3 screen unit numbers and set
the aspectRatio16x9 parameter to 0.
Output Freeze Mode
When the still store is displaying a still or a stopped animation, the user can
set the still store to display a complete frame or restrict output to one of the
two fields. Frame output is ideal for stills since full vertical bandwidth is
used. However, if the image contains motion (as would be the case for an
animation or a still grabbed from moving video), frame output may have
too much jitter. Selecting one of the field modes will eliminate the jitter at
the expense of vertical bandwidth.
Field interpolate modes present the selected field during its display period
and interpolate the other field by averaging adjacent lines from the selected
field. Field replicate modes simply output the selected field during both
field times.
Table 127.
Image
Format
Aspect
Ratio
Left Edge Right Edge Top Edge Bottom Edge
525/60
4:3 -4.07 +4.07 +3.08 -3.08
16:9 -- -- -- --
625/50
4:3 -4.17 +4.17 +3.05 -3.05
16:9 -- -- -- --
1280 x 720 or
1920 x 1080
16:9 -16.272 16.272 9.1125 -9.1125