1 March, 2005
V1682OPMA.doc
Page 17 of 32
4.6.2 Display Control
In some applications it may not be desirable for the on screen displays to be permanently keyed into
the SDI output of the unit. The on-screen displays are controlled in the
VID OSD
menu using front
panel control.
Within
VID OSD
there are two controls, the first of these,
VALIDMtr
, is used to turn the displays on
and off, also there is the ability to put the displays into ‘
auto
’ mode; this only keys the displays into
video, when a test pattern from a V1681 VALID generator is detected. The second control,
SDI
Src
, selects which of the two SDI inputs to use; note that this control is only operable if the unit is
set up for two SDI inputs (see Sec. 2.5.2).
4.6.3 Delay and Source Display
Audio / video delay, and audio source information is displayed in the left hand display. Source
information is shown on the left hand side of the display, while the audio/video delay is shown on
the right-hand side. The audio/video delay, is also displayed as a horizontal bar graph with a
logarithmic scale.
In Figures Figure 4.2 - Figure 4.4 are shown the delay/source display in various states. Figure 4.2
shows the system operating correctly, with audio and video synchronised, and all four audio inputs
fed by the correct V1681 source.
A more complex scenario is shown is Figure 4.3. Here, all four audio channels are connected, but
the two stereo pairs, A and B, are swapped over, and the video has been delayed by 35ms. The
channel swap over is indicated by the source text on the left hand side of the display. A display
such as BL > AL implies that the AL input of the unit is being fed by output BL form the V1681
generator. Also the audio feeding input BL has been inverted, which is shown by the down arrow -
see Figure 4.3(f).
Figure 4.4 shows fail conditions. Here the audio sources are of an unknown nature, indicated by
showing ?? > AL etc (a). Also the VALID with the strike through, and red cross (e) show that no
VALID test pattern has been detected. The delay measurements on the right hand side (d) show
dashes, as the delay is not calculable.
a
c
b
d
Figure 4.2 – All inputs from correct source, audio and video in sync.
a - V1681 audio output is connected to the correct
V1682 audio input
b - Delay bar showing no delay.
c - Delay showing 0ms
d - VALID symbol and tick, indicating the presence of
a VALID test pattern.
