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2.1 Agility/iPATH features
2.1.1 AFZ lossless codec
The AFZ compression scheme is primarily focused on improving the performance for "natural" images (i.e. photographs and
movies) and is automatically selected whenever there is a benefit to do so. The AFZ codec is lossless and is very low latency (a
small fraction of a frame delay). It generally achieves 50% improvement (in compression) over the RLE scheme for any areas of
the screen that consist of images, gradients, shadows etc., elements commonly found in modern desktop environments.
To maintain compatibility with non AFZ -enabled transmitters and receivers there is an automatic switching method which will
revert back to RLE compression when a Agility R1 receiver is connected to the newer Agility R2 series or Agility Dual.
2.1.2 New feature: AFZ+ codec
AFZ+ compliments the existing AFZ codec by providing greater compression for increased speed where pixel perfect results are
not the primary focus. The transmitter video configuration page allows you to choose the required compression mode. Choices
are:
• 'Pixel perfect' - only uses pixel perfect AFZ,
• 'Adaptive' - guarantees frame rate, builds to pixel perfect,
• 'Smoothest video' - forces the maximum compression, or
• 'Advanced' - allows you to choose the mode:
2.1.3 Magic Eye (anti-dither support added)
The Magic Eye feature increases performance and reduces network traffic when Agility units are used with Apple Macs and other
host computers that have dithered video output. It also improves performance if the video source is noisy (e.g. from a VGA-to-DVI
converter).
Dithering is a technique used by some graphics cards to improve perceived image quality by continuously varying the color of each
pixel slightly. This gives the illusion of more shades of color than the display can really reproduce, and smooths the appearance of
gradually shaded areas in images. Unfortunately dithering is an issue for KVM extenders such as Agility because it makes the
image appear to be changing all the time even when it is static, thus creating much more network data than can be carried by a
Gigabit Ethernet. The result is a reduction in video frame rate, which the user sees as slow mouse response.
Magic Eye works by ignoring small variations in the video from frame to frame. It is enabled by default as it is not obvious to the
user that his poor mouse behavior is caused by dithering. In most cases Magic Eye is invisible, but it can produce slight color
inaccuracies on the monitor. For full color accuracy, Magic Eye can be disabled (within the transmitter video configuration page)
for video sources which are not dithered or noisy.
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• 'AFZ only (pixel perfect),
• 'AFZ+ Minimum compression',
• 'AFZ+ Middle compression', or
• 'AFZ+ Maximum compression'.
Chapter 2: Overview
Page 9
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