Avocent SPC420 manual Contrast and brightness, Detection thresholds, Automatic video adjustment

Chapter 19: Using the Video Viewer 269

Contrast and brightness

If the image in the Video Viewer window is too dark or too light, select Tools - Automatic Video Adjust or click the Automatic Video Adjust button. This command is also available in the Video Adjustments dialog box. In most cases, this will correct video problems. In those cases where clicking on Auto Adjust several times does not set the contrast and brightness as desired, adjusting the contrast and brightness manually may help.

First, increase the brightness. Do not go more than 10 increments before moving the contrast. Generally, the contrast should be moved very little.

Detection thresholds

In some cases, noise in the video transmission keeps the packets/sec count up. This may be seen when little dots change in the area of the cursor when it is moved. Varying the threshold values may result in “quieter” screens and improved cursor tracking.

Noise Threshold and Priority Threshold values may be modified if you are using standard video compression. Block Noise Threshold and Pixel Noise Threshold values may be modified if you are using the KVM switch DVC algorithm upgrade. Default threshold values can be restored by clicking Auto Adjust Video.

Block noise threshold and pixel noise threshold

The Block Noise Threshold and Pixel Noise Threshold values set the minimum color levels in terms of changed video blocks and pixels per thousand that are allowed.

•The Block Noise Threshold sets the minimum color change that will occur in a single video block. Increasing the value will reduce the network bandwidth. Decreasing the value will make the size of these artifacts smaller.

•The Pixel Noise Threshold sets the minimum color change in a single pixel. Decreasing the value will reduce the number of low-contrast artifacts, but will increase network bandwidth.

Automatic video adjustment

NOTE: You may also select Tools - Automatic Video Adjust from the Video Viewer menu or click the Automatic Video Adjust toolbar icon to automatically adjust the video.

In most cases, you will not need to alter the Video Settings from the default. The system will automatically adjust and use the optimal video parameters. The DSView 3 management software performs best when the video parameters are set such that no (0) video packets are transmitted for a static screen.

You may easily adjust your video parameters by clicking on the Auto Adjust Video button in the Manual Video Adjust dialog box, which instructs the KVM switch to optimize the video to ideal settings.

A green screen with yellow lettering may appear during auto-adjustment.