Introduction to CEC: HDMI’s Under-appreciated Control Functionality

CEC (Consumer Electronics Control) is a HDMI function that enables execution of commands to control other CEC-enabled devices that are connected through HDMI with minimal or no user intervention. For example, turning on a DVD player can automatically turn on the TV and change its active input port through messages defined under “One Touch Play” feature of CEC protocol.

The possibilities in which CEC can be implemented is practically endless, but let’s take Google Chromecast as an example on how CEC is put into use through mobile apps. As some of you may already know, Google Chromecast is a networked audiovisual (multimedia) set-top-box device manufactured by Google. When Chromecast is connected to a TV with HDMI input that supports CEC, its app counterpart can be used to control the set-top-box and the TV, see below:

The mobile device where the Chromecast app is installed becomes a personalized remote control. The app remote can be used to search, browse, play, pause, rewind, fast forward, and it could even control the volume of the TV. So if you are you thinking of a connectivity solution among multimedia devices, maybe you can implement it through HDMI’s CEC functionality. For your quick reference, some of the feature function of CEC protocol are listed bellow:

• One Touch Play allows devices to switch the TV to use it as the active source when playback starts
• System Standby enables users to switch multiple devices to standby mode with the press of one button
• One Touch Record allows users to record whatever is currently being shown on the HDTV screen on a selected recording device
• Timer Programming allows users to use the electronic program guides (EPGs) that are built into many HDTVs and set-top-boxes to program the timer in recording devices like PVRs and DVRs
• Tuner Control allows a component to control the tuner of another component
• OSD Display uses the on-screen display (OSD) of the TV set to display text
• Device Menu Control allows a component to control the menu system of another component by passing through the user interface (UI) commands
• Remote Control Pass Through allows remote control commands to be passed through to other devices within the system
• System Audio Control allows the volume of an AV receiver, integrated amplifier or preamplifier to be controlled using any remote control from a suitably equipped device(s) in the system

 

How manufacturers call their CEC implementation?

 

 

 

 

Depending on the manufacturer, the CEC function is named differently. Naming the CEC function differently is actually quite confusing for the user, but this was a marketing inevitability since manufacturers try to induce customers to buy their complete multimedia set, i.e. their TV, Blu-ray Player, Set-top-box, AV amps, and maybe game console.

The result of this “CEC branding war” is customer confusion and sometimes real fragmentation as some “CEC” commands were developed to work only when connected with the same CEC brand (that is, the same manufacturer).

The common CEC protocol is standardized through the HDMI specification. The standard specifies all the commands and expected behavior under common user interactions. There are also minimum support requirements for devices that supports CEC protocols. This means that devices that claims to support CEC should be able to work with another CEC device if they follow the requirements of the HDMI specification correctly. For example, Apple TV’s CEC function should be able to work with any other TV that supports CEC, no matter what brand it is.

Interoperability among CEC devices through minimum support are specified and required, but is not guaranteed. There are some glitches and non-compliant implementation out there of course, but the overall interoperability among CEC devices is satisfactory. So if your local salesman is pitching you to buy the same CEC brand for all the parts of your multimedia set for maximum interoperability, I’d say OK.

But if you do not need maximum interoperability demand, then you could buy different brands and expect to get minimum CEC interoperability among your devices.  So it depends on you really. At one of our engineers’ home, he has a Toshiba TV, a Sony PlayStation, an Apple TV, and a Yamaha AV amplifier. All devices are connected through the CEC network, and he said the CEC function among the devices works just fine.

Anyway, for your information we list some of the CEC brands out there in the market, see which CEC brand(s) do you have:

• Anynet+ (Samsung)
• Aquos Link (Sharp)
• BRAVIA Link, BRAVIA Sync, Control for HDMI (Sony)
• CE-Link, Regza Link (Toshiba)
• E-link (AOC)
• EasyLink (Philips)
• Fun-Link (Funai, Sylvania, Emerson, Magnavox, Philips)
• HDMI-CEC (Hitachi)
• INlink (Insignia)
• Kuro Link (Pioneer)
• NetCommand for HDMI, Realink for HDMI (Mitsubishi)
• RIHD (Remote Interactive over HDMI) (Onkyo)
• RuncoLink (Runco International)
• SimpLink (LG)
• T-Link (ITT)
• VIERA Link, HDAVI Control, EZ-Sync (Panasonic)
• CEC (Vizio)

If you’d like to know more about CEC you could read this article from Wikipedia first. If that is not enough, I’d suggest you download the old HDMI Specification version here (registration required).