ClearOne Digital Media - Manual (Page 70)

HDCP Keys continued
Following is a more technical description of HDCP, beginning with two primary parts:
1 . Authentication
2 . Encryption
Using HDCP, authentication ensures all HDMI connected devices receive only content that is
licensed and authorized. Only after successful authentication will the display device output a
stream.
In a multi-point AV system, HDCP encrypts each segment of an AV transmission, and HDCP
authenticates every device via the source. Devices that re-transmit HDCP content inform
the source of all the downstream connections. This means every HDCP device has a unique
ID, known as a Key Selection Vector or KSV. The KSV must be passed to the source, which
then verifies every device before beginning to transmit content. In large systems, it is this
authentication process that frequently creates extended switch times when a new source is
selected. With StreamNet, because of its persistent architecture and method of handling
keys, switch time is nearly eliminated leading to a vastly improved user experience.
It is important to note that all sources have a predetermined limit on the number of display’s
which may be connected. This limit is caused by the number of KSV’s the source is able to
accept. Though HDCP allows for up to 127 devices, sources generally support as few as ten
and we have even found some which only support a single display.
The reason this can be a problem is when a repeater presents a source with too many
KSV’s, the source will stop transmitting content with no explanation. For this reason
installers must be aware of KSV limits in any HDMI installation involving more than one
display. We highly suggest testing devices in the field before completing a system design to
ensure your intended system results and performance may be achieved.
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pg 70 StreamNet Digital Media and System Design Reference Guide
Solving Digital Media Related AV Problems