Nevion DAC-AVA-DMUX - Manual (Page 25)

DAC-AVA-DMUX Rev. A
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(because the main input is selected to be an internal generator, and therefore always
present), the card will also display the unreachable levels as
‘–‘.
The switching is always latching, and to get back to the main input while the other input is
still present, the user must press Reset. Note that if the fallback also disappears, the
module will start searching at the main input again.
Hold time and lock time can also be adjusted. They specify how long a signal can be
missing before the next input in the prioritized list is attempted, and how long a lost signal
has to be present before it is considered OK again, respectively.
4.3.8 Video generator
The video generator can produce several simple signals: Color bar, Color bar with a moving
box, Check field and Flat field.
The flat field feature is controlled by setting the luma and chroma values (each is a 10bit
value, 0-1023), or by selecting one of the pre-defined colors (black, white, yellow, cyan,
green, magenta, red, or blue).
By default he generator is selected as the video source if there is no video signal present at
either of the video inputs. The video standard will then be determined by the legal video
input last seen by the card. The Video format selector has no effect in this mode.
The generator may also be forced on from Multicon GYDA by selecting the video generator
as main input in Video in. The video standard is then determined by the Video format
selector. This selector will override video input but the internal generator will still be locked
to the input signal. In other words: For correct generator output in this mode, the input must
either be missing or the input must be of the same frequency base as the selected output
standard.
Figure 16: Multicon GYDA view of the video generator
4.3.9 Video processing
The video processing block consists of a gain and offset adjustment, and a video payload
legalizer.
Figure 17: Multicon GYDA view of the video processing block
4.3.9.1 Gain and offset
The gain and offset adjustments are done separately for the Y, Cb and Cr samples.
Range Multicon GYDA
Luma gain 0
– 3.9999
Chroma gain 0 – 3.9999
Luma offset (gain =1) 511.75 – 511.75 in sample values
Chroma offset (gain = 1) 255.75 – 255.75 in sample values
4.3.9.2 Video payload legalizer
The legalizer hard clips the upper and lower limit of the video payload. With the legalizer
enabled these limits are:
Upper limit Luma: 3ACh
Chroma: 3C0h