epiphan KVM2Ethernet, User Manual

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3. Windows VGA2Ethernet user interface About EDID
User Guide Page 69
The real maximum frame rate is usually lower than the
theoretical maximum frame rate because the real maximum frame
rate is limited by the video capture workstation CPU and
memory and the load on the ethernet connection.
For the VGA2Ethernet device n can be from 1 to 3 depending on
the capture mode. If the color depth is RGB24, n is 3 bytes per
pixel. If the color depth is RGB16, n is 2 bytes per pixel and if the
color depth is RGB8/Grayscale, n is 1 byte per pixel.
Because the VGA2Ethernet device includes hardware
compression the maximum real frame rate depends on the
entropy (statistical properties) of the input VGA signal. In other
words, the frame rate depends on how well the signal can be
compressed, or on how much of the next frame is different from
the previous one. The frame rate can range, from less than non-
compressing in the worst-case scenario (because the format for
compressed data adds extra overhead) to 125 frames per second
(hardwired limit) if almost nothing changes in the image.
About EDID
Extended display identification data (EDID) is provided by a
video display device (usually a monitor) to describe its
capabilities to a video source. The video source uses the EDID to
determine the resolution, color depth and other settings that the
monitor can accept.
EDID is defined by a standard published by the Video Electronics
Standards Association (VESA). The EDID includes manufacturer
name, product type, phosphor or filter type, timings supported
by the display device, display size, luminance data and (for
digital displays only) pixel mapping data. EDID is required for
DVI video sources and can also be used by VGA video sources.
When you connect a VGA2Ethernet or KVM2Ethernet device to a
video source, the video source sees the device as a monitor. Just
like a monitor, the device contains and EDID that is used by the
video source to determine the video signal to send to the device.