GUIDE TO INSTALLATION AND OPERATION
XVP-1801 |
17
The offset from the VREF can be variable, but a distance of greater than 10 lines could create an artifact in
the active video. If the two signals are more than 1 line apart, we will see a vertical jump at the moment of
switching that is proportional to the number of vertical lines of offset between the two signals. This will last for
only one frame. There may also be problems in the transition when in the AFD automatic or forced mode.
When a reference is present and the deglitcher is active, the card reports the difference in timing between
the input and the reference when the transition occurs.
•
If the reference is missing when the deglitcher is activated, the Input timing to reference box will
indicate “Missing reference” in red, and the reference status icon at the top of the iControl window will
turn red and show the message “Reference missing”.
•
If the deglitcher is OFF, the reference status icon will be grey, and its message will read “Reference
absent”
To perform a glitch-free switch between two sources, they must be in the same clean switch region. A clean
switch region is contained within ± ½ line about an H=0 point in the reference signal, as shown by the dotted
lines in the figure. There is a clean switch region centered on every H interval. As you can see, vertical
alignment with the reference is not important for the deglitcher to operate properly.
You may switch between signals A, B or C, without any glitch, and also between signals D
Ù
E and signals
F
Ù
G. Any other transition, like A
Ù
D, will cause a vertical image shift for one frame.
To determine whether a clean hot switch is possible, you need to determine whether the two input signals lie
in the same clean switch region. There are two ways to measure the position of the signals with respect to
the reference:
•
Use the deglitcher tab in iControl (Input
Æ
Deglitcher)
•
Use the controller menu in Appendix 2 (video
Æ
timing
Æ
in timing to ref).
When the deglitcher mode is on, each of these sources will display the alignment offset between the
reference signal and the input signal. Knowing the offset for both input signals, you can determine if they are
in the same clean switch region. If so, any hot-switch between those two signals will be glitch less.