Decoder video bandwidth tab
To access the video
Bandwidth
tab from the
Device
tab, click the
Display0
link and, in the
Display
tab, click the
video
link.
Figure 42.
Video Bandwidth Tab
This page provides statistics on the video stream and allows the decoder video buffer to be
monitored and configured, if necessary.
If required, modify the
Window
Name
by editing the current value and clicking
Update
. It is
not necessary to name this field for normal operation.
Decoder video buffer
The delay time between the data being input to the encoder and output on the decoder is
controlled by setting the
Channel
Delay
and the
Frame
Delay
. The channel delay is unique
to each channel of video, audio, or data and is set in seconds. The frame delay can only be
modified on the video channel and is converted from frames to seconds depending on the
video frame rate that the decoder is currently receiving. The delay time is the sum of these
two values and is shown in the
Total
Delay
field.
In normal operation on a LAN,
Channel
Delay
should be set to 0.0 and
Frame
Delay
should be set to 6 frames. This gives an end to end delay of 100ms on a 60 fps signal.
On a WAN the
Channel
Delay
parameter should be used to add an amount corresponding
to the one-way network delay.
Under normal operational circumstances, there is no requirement to adjust the
Frame
Delay
setting and the buffer is managed automatically.
The hardware has a minimum delay requirement of 2.5 frames in progressive mode and 3.5
fields in interlace mode. A
Total
Delay
less than these values results in uneven playback
and pipeline underflow alarms.
NOTE:
There is one exception to this rule — setting the
Total
Delay
to
0.0
(zero)
places the system in a special minimum-latency mode. When operating with minimum
latency, the display attempts to decode data as soon as it arrives. This reduces the
elastic feel when using a remote cursor but can cause the display to be more jumpy
and the lip sync to an audio stream to be lost.
Excessively long delays cause data to build up in a software buffer within the decoder. When
the build up exceeds 10 video frames, frames of data are discarded, which can cause
on-screen artifacts.
VNM 250 • VNM 250 GUI Overview
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Summary of Contents for VN-Matrix 250 Series
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