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7700 MultiFrame Manual
7735AVC-LB Video Composite Encoder and Audio DAC with SoftSwitch
7.7.10.2. Setting the Picture Freeze Duration
Fault definitions
Picture freeze duration
6 to 902 frames
302 frames
When increasing Picture noise level, it is recommended that you increase Picture freeze duration as well.
This is because the higher the Picture noise level, the lower the equipment's motion sensitivity, thus long
periods without significant on-screen movement are more likely to trigger a "false" freeze alarm.
7.7.10.3. Optimizing the Picture Noise Level and Picture Freeze Duration Parameters
Setting up the optimum Picture noise level and Picture freeze duration parameters will depend on the
amount of noise in the video path from the first equipment with freeze-frame capability to the monitoring
point. The system designer should determine the maximum amount of time permissible between the
moment of freeze and the alarm.
Setting this time as high as tolerable has two benefits:
•
It lowers the frequency of "false" freeze alarms generated when a perfectly valid content contains
long motionless periods
•
It allows raising the Picture noise level parameter, without increasing frequency of "false" freeze
alarms
It is suggested that Picture noise level should be set after setting the Picture freeze duration.
If the video path is fully digital, then set the Picture noise level depending on bit-error rate of the link as
follows:
•
For bit-error rates less than 1 in 10
•
For bit-error rates greater than 1 in 10
If the path is even partially analog and if the user can place the equipment farthest upstream in the video
path to go to a 'freeze frame' mode, then the Picture noise level should be optimized by initiating the
'freeze frame' mode in the upstream equipment and adjusting Picture noise level as low as possible,
without losing the freeze alarm on the 7735AVC-LB. The user should note that because of the random
nature of noise, the freeze alarm might be intermittent at some Picture noise level settings. The optimal
Picture noise level setting is obtained when the loss of freeze alarm in the AVC occurs no more then once
every 5 minutes.
If the path is even partially analog and the equipment farthest upstream in the video path cannot go to a
'freeze frame' mode, then Picture noise level should be optimized by adjusting it as high as possible. If
the user triggers false freeze alarms more often than acceptable; lower the Picture noise level setting.
Since the acceptable rate could be on the order of a day perhaps (depending on the facility), this
adjustment procedure may consume a couple of days.
7735AVC-LB - 32
This control sets duration, in video frames, of video activity under the
Picture noise level that is considered a fault.
E-12
, set value in the range of 1 to 5
E-12
, set value in the range of 6 to 10
Revision 1.6
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