Deep Dive into CEC Over IP Control: Hardware, Software, and Implementation

CEC over IP control is highly versatile but requires the right combination of hardware, software, and networking to function effectively. Below is an in-depth look at how to implement CEC over IP for various AV systems.

1. Hardware Requirements

To successfully implement CEC over IP, you’ll need hardware that supports HDMI-CEC and network communication. Some common hardware includes:

CEC Adapters

These devices translate IP-based commands into CEC signals and vice versa:

Global Caché IP2IR or iTach Flex: Versatile adapters for IR and CEC control.
Pulse-Eight USB-CEC Adapter: A popular choice for PC-based setups.
HDMI Matrix Switches with CEC Support: Some HDMI switches include built-in CEC control over IP, such as those from Atlona, Kramer, or Extron.

AV Receivers

Most modern AV receivers support CEC, enabling them to act as hubs for connected devices. Look for models that explicitly list CEC over IP compatibility.

Displays and Sources

Ensure that all HDMI-connected devices (e.g., TVs, projectors, Blu-ray players) have CEC enabled. Typical labels for CEC across brands include:

Samsung: Anynet+
Sony: BRAVIA Sync
LG: SimpLink
Panasonic: VIERA Link

Network Switches

A robust IP network is crucial for reliable communication. Managed switches with VLAN capabilities are ideal for isolating AV traffic.

2. Software Tools

Control systems often rely on middleware or software to facilitate CEC over IP communication. Here are some common tools:

Middleware for CEC over IP

Roomie Remote / Simple Control: A user-friendly platform for controlling AV systems using CEC and IP protocols.
Home Assistant: Open-source home automation software that supports CEC with adapters like Pulse-Eight.
Control4, Crestron, or Savant: High-end control systems that support CEC and integrate with other IP-based devices.

API Integration

Some devices, like HDMI matrix switches, offer APIs for direct IP control. Examples include:

TCP/IP Commands: Some hardware supports plain text or HTTP commands to trigger CEC actions.
Telnet/SSH: Used for devices that support advanced IP scripting.

CEC Libraries for Custom Development

libCEC: A powerful open-source library that works with Pulse-Eight adapters. It allows you to write custom scripts for CEC control in Python, C++, or Java.
PyCEC: A Python wrapper for libCEC, ideal for building automation scripts.

3. Network Configuration

A stable network is vital for CEC over IP control. Follow these guidelines:

Use Static IPs: Assign static IPs to all AV devices and controllers to prevent connectivity issues.
Enable QoS: Configure Quality of Service (QoS) settings to prioritize AV traffic.
VLANs for AV Traffic: Segregate AV traffic from other network traffic to ensure low latency.
Port Forwarding: If remote access is required, configure port forwarding or use a VPN.

4. Scripting and Commands

With the hardware and software in place, you can begin scripting custom commands. Below is an example using PyCEC:

Python Script for Power Control

pythonCopy codeimport cec

# Initialize CEC
cec_config = cec.libcec_configuration()
cec_config.strDeviceName = "CEC_Controller"
cec_config.bActivateSource = 0
cec_config.clientVersion = cec.LIBCEC_VERSION_CURRENT
cec_adapter = cec.ICECAdapter.Create(cec_config)

if cec_adapter.Open("RPI"):
    print("CEC Adapter opened successfully.")

# Send Power On Command to all devices
cec_adapter.PowerOnDevices()

# Standby all devices
cec_adapter.StandbyDevices()

cec_adapter.Close()

Sample HTTP API Request

For hardware like an HDMI matrix switch:

httpCopy codePOST http://<switch_ip>/api/cec
Content-Type: application/json

{
    "command": "power_on",
    "target": "0.0.0.0" // Address for all devices
}

5. Debugging and Testing

Tools for Monitoring CEC Traffic

CEC-O-Matic: A tool for debugging CEC traffic on a PC.
Wireshark: Use this to analyze IP traffic and verify commands sent over the network.

Common Issues and Solutions

Devices Not Responding: Ensure CEC is enabled on all devices.
Conflicting Commands: Avoid overlapping commands by using unique logical addresses.
Latency: Check network congestion and prioritize AV traffic with QoS settings.

6. Practical Example: Conference Room Setup

In a typical conference room:

Hardware: Install a CEC-capable HDMI switch (e.g., Atlona) and connect it to displays and sources.
Software: Use Control4 or Crestron for centralized control.
Use Case: A single IP command can power on all displays, set the source to a laptop, and adjust the audio to a predefined level.

jsonCopy code{
    "commands": [
        { "device": "Display1", "action": "power_on" },
        { "device": "AudioSystem", "action": "set_volume", "level": 50 },
        { "device": "HDMISwitch", "action": "set_source", "input": 2 }
    ]
}

This setup ensures a seamless and efficient system.

Brooks AV