User`s manual

Alcorn McBride Digital Video Machine HD User’s Manual Rev 1.0
62
Synchronization
.
One of the most powerful features of the Digital Video Machine is its ability to
synchronize to an external video source. This ability makes the DVMHD a perfect
solution for the following type of applications:
• Synchronized playback on multiple displays
– Any application that entails
side-by-side displays, edge-blended projectors, or 3D projection require
perfect frame synchronization between multiple video sources. Without it,
each display would be playing a different portion of the video at different
times, ruining the desired effect.
• Tightly Synchronized Shows
– Since the DVMHD can slave to an external
video clock; it has the ability to keep perfect time with other devices that are
slaved to the video clock as well. Some examples of these devices might be
other video players, audio players, SMPTE Generators, or Show Controllers.
• Broadcast Applications
– For reasons that are beyond the scope of this
manual, broadcasters typically require all of their video equipment to be
slaved to an external sync source.
Configuring the DVMHD for External Sync
In order to lock
several DVMHD’s
together with External
Sync, you will need a
Video Sync
Generator. If you
require advice or
product
recommendations,
please contact your
Alcorn McBride
representative.
The yellow LED
located next to the
sync connectors only
illuminates when a
sync signal is
detected. This
indicates that the
DVMHD is using that
sync signal to
generate video.
Sync Mode
The Digital Video Machine is designed to accept either of the two most widely used
types of sync; Composite sync and Blackburst sync. Once you determine what type
of sync source you intend to use, you must set the Sync Mode DIP-Switch to the
corresponding type. If you are using Composite sync (typically referred to as C-
Sync), the Sync Mode DIP-switch must be in the ON position. Therefore, setting the
DIP-switch to the UP position would configure the DVMHD for Blackburst sync.
Setting this switch is necessary for the DVMHD to interpret the sync signal reliably.
75Ω Termination
It is always good practice to terminate every active sync line with 75Ω. This means
that the 75Ω DIP-switch should always be ON whenever the DVMHD is receiving sync
directly from a sync generator or video distribution amplifier. The only occasion where
you would want to disconnect the 75Ω termination is when you are ‘splitting’ a sync
line. An example of this would be daisy-chaining a single sync line to multiple
DVMHD’s using BNC T-Connectors. In this scenario, you would only want to
terminate the last DVMHD in the chain.
Video Format
The last important step in configuring a Digital Video Machine to receive external sync
is verifying that the video format of the DVMHD matches that of the incoming sync
signal. For example, you do not want to feed a PAL sync signal into a DVMHD
configured for an NTSC video format (like 1080i29.97 or 720p59.94). If you were to
do so, the DVMHD would reject the sync signal and generate its own instead. The
DVMHD would indicate this by turning OFF the yellow sync LED. The DVMHD’s
video format can be changed at any time using the front-panel configuration menu or
Serial/Ethernet commands.