Extron Electronics VN-Matrix 250 User Guide - Manual (Page 56)

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:
z Video Quality
z
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 may 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 50