4
VM-400HDCP - Overview
standard resolution is 2.75 megapixels (including blanking interval) at 60Hz
refresh. For practical purposes, this allows a maximum screen resolution at 60Hz
of 1,915×1,436 pixels (standard 4:3 ratio), 1,854×1,483 pixels (5:4 ratio), or
2,098×1,311 (widescreen 16:10 ratio). A dual link doubles the number of TMDS
pairs, effectively doubling video bandwidth at a given pixel clock frequency.
The maximum length of DVI cables is not included in the specification since it is
dependent on the video resolution and refresh rate. In general, cable lengths up to
4.5m (15ft) will work for displays at resolutions of 1,920×1,200. This resolution will
work even up to 10m (33ft) if appropriate cable is used. Cable lengths up to 15m
(50ft) can be used with displays at resolutions up to 1,280×1,024. For longer
distances, the use of a DVI booster is recommended to mitigate signal
degradation. DVI boosters may use an external power supply.
3.2
About HDCP
The High-Bandwidth Digital Content Protection (HDCP) standard developed by
Intel protects digital video and audio signals transmitted over DVI or HDMI
connections between two HDCP-enabled devices to eliminate the reproduction of
copyrighted material. To protect copyright holders (such as movie studios) from
having their programs copied and shared, the HDCP standard provides for the
secure and encrypted transmission of digital signals.
3.3
Defining EDID
The Extended Display Identification Data (EDID) is a data-structure provided by a
display, to describe its capabilities to a graphics card (that is connected to the
display’s source). The EDID enables the
VM-400HDCP
to “know” what kind of
monitor is connected to the output. The EDID includes the manufacturer’s name,
the product type, the timing data supported by the display, the display size,
luminance data and (for digital displays only) the pixel mapping data.
EDID is defined by a standard published by the Video Electronics Standards
Association (VESA).
