Crestron DM-RX1-1G Specifications download pdf (Page 11)

Crestron DigitalMedia™ Design Guide

Check website (www.crestron.com) for product availability 7

Installers must be aware of KSV limit issues in any HDMI installation that involves more than one display. Be sure to research

how your equipment handles scenarios that violate source KSV limits using the device list (page 42) and by testing devices

in the field.

Consumer Electronics Control (CEC)

Each HDMI cable contains a communication link that enables devices connected via HDMI to talk to each other. This protocol

is called Consumer Electronics Control (CEC). When a control system is in place, however, you don’t want other devices

issuing commands. CEC is supposed to contain industry standard commands for interoperability, but inconsistent support

from CE manufacturers has caused a wide variation in the functions that can actually be triggered from each device. Some

examples of this functionality that Crestron has discovered are:

 Multiple DVD players from the same manufacturer, in the same system, communicate with each other so that only

one can play at a time. Every time one player is issued the play command, the player sends a pause command to

the other players over CEC

 When a Blu-ray player is turned off, it sends a power off command, turning off all the displays connected to

the system.

These functional commands are a major issue, because they are sent behind the scenes and without your knowledge.

DigitalMedia breaks the communication path between the HDMI devices that are connected to the switch, so these commands

cannot be sent without your approval. In addition, DigitalMedia provides a method to issue CEC commands from a control

system, so the communication link can be used for your benefit, as an alternative to IR and RS-232 control.

Audio

HDMI provides the only transmission link for 7.1 channel HD audio. However, unlike traditional analog video sources, HDMI

sources usually do not transmit multi-channel and 2-channel audio at the same time. This becomes a problem for multi-room

distribution, in which a mixture of surround sound and stereo audio rooms are present. HDMI sources will often shut off analog

outputs when sending audio over HDMI.

Audio Distribution

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Crestron DM-RX1-1G Specifications Page 11