Extron electronics VN-Matrix 250 Series, User Manual

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Video quality and Bandwidth panel — advanced control
Figure 34. Bandwidth Tab: Video Quality and Bandwidth Panel
The
Video Quality and Bandwidth
panel (click
More Detail
, if necessary) provides a
greater degree of control over the encoder compression settings.
These controls are divided into two main categories:
•
Video Quality
•
Bandwidth
They provide access to the complete set of image quality and bit rate tools for the VNE 250.
When controls in this section duplicate controls found in the
Bandwidth Management
panel,
the settings in both panels coincide.
Video Quality panel
•
Spatial compression — this level is set using the
Luminance
and
Chrominance
drop-down lists.
A luminance value of
0
provides the minimum spatial compression; a luminance value of
10
provides the maximum spatial compression.
These controls are normally locked (using the
Lock
check box), with an optimal
offset of 2 units between them. If required, the chrominance compression can be set
independently by clearing the
Lock
check box.
NOTES:
• By default, the luma and chroma offset is set to 2 whenever the simple
(standard) management scheme is selected.
• A spatial compression setting of 4/6 (luma 4; chroma 6) provides visually
lossless compression.
•
Temporal compression — is applied by selecting the
Temporal
check box (this
option is selected by default). Temporal compression causes data to be transferred only
when a change occurs between frames.
•
Threshold setting — modifies the detection point of the temporal compression
algorithm. A value of
0
results in all changes between frames being sent. As the
threshold value is increased, only changes above a certain level are sent, thus reducing
the bit rate.
This control compensates for image sources that have a level of noise in them. In
general, there is always some noise in any source produced by an analog method. By
applying a threshold, this noise can effectively be ignored by the PURE3 compression
engine, resulting in a lower transmitted bit rate.
A setting of
0
is suitable for DVI computer-generated sources. Sources with more noise
or video-type motion should use a setting between
1
and
4
. Camera sources should
always use a value greater than
1
.
•
Chroma setting — controls whether the temporal algorithm should consider changes
in the color or chrominance of the image. Enabling chroma gives better results on digital
simulation source types. However, chroma thresholds can increase the transmission
bandwidth by up to 20%; therefore, it should be disabled on bandwidth sensitive
systems. It is usually not required on video or camera source types.
VNM 250 • VNM 250 GUI Overview 51