MICROTRONIX DX-4400 Series, Руководство пользователя

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DX-4400
– 3G-SDI Text & Graphics Overlay Inserter – User Manual
Page 43 of 125
3.9.2 Video Zoom Commands
The Video Zoom Commands work in PiP TI , LPiP TI (for input 2 only), ZDual TI , and Z4K TI modes. Different
modes have different zoom capabilities. The Z4K TI and ZDual TI modes support high zoom magnifications. The
LPiP TI mode supports high zoom magnifications by default, but also supports a restricted range zoom mode that
has the benefit of reduced latency on the second input. The PiP TI mode always operates in the restricted zoom
range mode.
In the restricted range zoom modes of operation, the total resulting magnification of the combined PiP and Zoom
functions is limited as follows: For 3 Gb/s modes, pixels cannot be magnified above 1x. For 1.5 Gb/s modes, a
total magnification up to 1.5x is possible. For SD modes, magnification can be a maximum of 3x. For example, a
3Gb/s video mode that is displayed as a PiP image at ¼ the frame size can be zoomed up to 400% because the
two commands combined produce a 1x pixel magnification. If the PiP size in this example was then changed to
full screen, the zoom would be automatically reduced to the maximum permitted value of 100%
In the high magnification zoom modes the maximum magnification that can be achieved depends on the video
mode. In center point zoom mode and for 1920x1080p resolution, the limit is approximately 32x magnification
(3200%) and for 1280x720p resolution, the limit is approximately 23x. The zoom function supports certain discrete
steps in magnification. When the zoom percentage is low, the zoom steps are small. At high magnifications the
steps become much larger. The zoom command selects the step nearest to the requested value.
Zooming can be performed around a center point or by specifying window coordinates. The center Zoom and
window Zoom are mutually exclusive; the last command sent takes effect. The settable values listed in Table 15
below.
Table 15: Zoom Command Syntax
Parameters Description of Command Syntax
ZCx
– Center Zoom for SDI input x where x = 1 or 2
C=
Sets the center zoom behaviour. The default value is 0.
The valid values and effects are:
0 Zoom around the center position.
1 Zoom around the center position preserving exact center position by avoiding zoom steps
which would cause a position shift.
2 Zoom around the center position preserving exact center position and aspect ratio by
limiting only zoom steps that meet these requirements.
C=0 gives priority to providing the maximum possible number of zoom steps. This mode selects
the closest pixel position to the requested center point, and closest width/height to the required
aspect ratio. This means the center can shift slightly between difference zoom steps. As a
result, this mode is not suitable for implementing a digital zoom lens effect because of the center
jitter that occurs as zoom changes.
C=1 provides fewer zoom steps by selecting only those that have the same exact center point,
but the aspect ratio is rounded to the nearest pixel.
C=2 provides the fewest zoom steps by selecting only those that have the exact center point
and aspect ratio. The number of zoom steps available is much less than the C=0 mode. In
particular, the 2048x1080 pixel mode has very few possible steps due to the 256:135 aspect
ratio.