Consumer Electronics Control (CEC) is an HDMI feature that allows devices connected via HDMI to communicate and control each other using a single remote or interface. CEC over IP Control extends this functionality by using an IP-based network to send and receive CEC commands, enabling centralized and remote control of HDMI devices.

This method is particularly useful in AV installations where devices are located in different rooms or require remote management. Instead of relying on a physical HDMI connection for CEC, commands are transmitted over the network, allowing greater flexibility and scalability.

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Common CEC Commands

Below are the most frequently used CEC commands, categorized by their function:

Power Control

• Standby (0x36): Puts the device into standby mode (turn off).
• Image View On (0x04): Wakes up the device or turns it on.

Volume Control

• Give Audio Status (0x71): Requests the current audio status (e.g., volume level).
• Set Audio Volume (0x44): Adjusts the volume level.
  • Parameters: Volume Level (0-127).
• Mute (0x43): Toggles mute on/off.

Source Selection

• Active Source (0x82): Indicates that the device is the active source.
• Set Stream Path (0x86): Switches the input to a specific source.
  • Parameters: Physical Address of the source.

Device Information

• Give Device Vendor ID (0x8C): Requests the vendor ID of the device.
• Device Vendor ID (0x87): Sends the vendor ID in response.
• Give Physical Address (0x83): Requests the physical address of the device on the HDMI bus.
• Report Physical Address (0x84): Sends the physical address.

Playback Control

• Play (0x41): Starts playback.
• Pause (0x42): Pauses playback.
• Stop (0x45): Stops playback.
• Fast Forward (0x48): Begins fast-forwarding.
• Rewind (0x49): Begins rewinding.

Menu and Navigation

• Menu Request (0x8D): Opens or navigates a device menu.
  • Parameters: Activate, Deactivate, or Query.
• User Control Pressed (0x44): Simulates a button press (e.g., “up”, “down”, “enter”).
  • Parameters: Button Code.
• User Control Released (0x45): Ends the button press event.

Broadcast Messages

• Request Active Source (0x85): Requests the current active source.
• System Audio Mode Request (0x70): Requests the audio system to turn on or off.
• System Audio Mode Status (0x7E): Broadcasts the current audio mode status.

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Advantages of CEC over IP Control

1. Centralized Control: Manage multiple HDMI devices from a single interface or app.
2. Extended Range: IP-based communication allows control over large distances.
3. Integration: Easily integrates with other AV systems and home automation platforms.
4. Scalability: Supports large-scale deployments, such as conference centers or auditoriums.
5. Flexibility: Eliminates reliance on physical HDMI paths for CEC communication.

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Practical Applications

• Turning on multiple displays and setting them to the correct input from a control room.
• Automating power and source selection across a networked AV system.
• Managing audio levels and routing in a centralized audio-video matrix.
• Scheduling playback and power settings remotely.

Implementation Notes

For successful implementation, ensure the following:

1. Devices are CEC-compatible and connected via HDMI.
2. The network supports low-latency communication for real-time control.
3. Software or middleware is configured to translate IP commands into CEC signals.