HDMI 之 CEC

HDMI CEC是HDMI傳輸的規範之一，CEC是「Consumer Electronics Control」的縮寫，中文可翻譯為「消費性電子產品控制」。

顧名思義，HDMI CEC是用來傳送工業規格的AV Link協定訊號，以此HDMI介面連接的多台AV器材，就可以使用單一遙控器來操控。

HDMI CEC為單芯線雙向串列匯流排，在HDMI 1.0協定中就制訂了，於1.2a版中有所更新。

 

The bus, known as the consumer electronics control (CEC) bus, is the basis for a new level of automatic control in HDMI-interfaced systems. With the recent release of a CEC compliance test specification and commercial CEC test equipment, consumer electronic companies are now poised to implement CEC in their products. In fact, new CECenabled products are expected to begin shipping in April 2006.

The basic technology of the CEC bus originated in Europe, on the SCART interface, where it’s been used with great success for many years. HDMI borrows and improves on the basic SCART technology, allowing AV products to discover and communicate with one another across a system. CEC makes possible global controls, which build on existing point-topoint E-DDC-based "plug & play" automation to minimize the number of IR remotes and key-presses required for basic operation of a system.

CEC assumes that all AV source products in a system are directly or indirectly connected to a “root” display. HDMI connections form an upside-down tree, with a display as the “root”, switches as “branches”, and various source products as “leaf” nodes. For example, CEC allows users to connect a mix of AV products, place a DVD into the player, press PLAY, and let CEC handle the rest.

CEC will automatically power-on the appropriate products, route the DVDplayer's audio output through the AVR to attached speakers, and route the player's motion picture to the Digital TV. Likewise, selecting a channel on the set-top-box will cause television audio to replace movie audio on the speakers and a TV picture to replace the motion picture on the Digital TV. Further, pressing the RECORD button on the recording device will cause the television program on the "root" to be automatically routed to and recorded on that device. In short, CEC enables automatic equipment discovery and simple "one touch" operation in HDMI-interfaced systems.

The CEC bus is a one-wire, “party line” that connects up to ten (10) AV devices through standard HDMI cabling. The CEC protocol includes automatic mechanisms for physical address (topology) discovery, (product type based) logical addressing, arbitration, retransmission, broadcasting, and routing control. Message opcodes support both device specific (e.g. set-top-box, DTV, and player) and general features (e.g. for power, signal routing, remote control pass-through, and on-screen display).

 

HDMI中的CEC有14个功能(OPTIONAL)

CEC 3 Feature Overview

CEC provides a number of recommended features designed to enhance the functionality and

interoperability of devices within an HDMI system. This section gives an overview of these

features.

• One Touch Play - Allows a device to be played and become the active source with a single

button press.

• System Standby - Enables the user to switch all devices to standby with one button press.

• Preset Transfer - Enables any tuner device to download the same set of presets as the TV.

It is used to auto configure a devices presets so no manual setup is required.

• One Touch Record - Offers a What You See Is What You Record (WYSIWYR) facility,

meaning that whatever is shown on the TV screen is recorded on a selected recording

device.

• Timer Programming - Allows a device (e.g. the TV) to set a timer recording on a recording

device.

• System Information - Queries the system to determine device addresses and configurations

(e.g. language and country)

• Deck Control - Enables a device to control (e.g. play, fast forward etc.) and interrogate a

playback device (a deck).

• Tuner Control - Allows a device to control the tuner of another device.

• Vendor Specific Commands - Allows a set of vendor-defined commands to be used

between devices of that vendor.

• OSD Display - Enables a device to use the on-screen display of the TV to display text

strings.

• Device Menu Control - Enables a device to control the menu of another device by passing

through user interface commands.

• Routing Control - Allows the control of CEC Switches for streaming of a new source device.

• Remote Control Pass Through - Enables remote control commands to be passed through

to other devices within the system.

• Device OSD Name Transfer - Enables devices to upload their preferred OSD name to the

TV. The TV can then use this name in any menus associated with that device.