CasperCG Developer Guide: Understanding Broadcast Graphics for Media Companies → Explore with me!

What is CasperCG?

CasperCG is an open-source, professional broadcast graphics system used by TV stations, streaming services, and media companies worldwide. It renders real-time graphics, overlays, and animations for live broadcasts, making it an essential tool for modern media production.

Architecture Overview

Understanding CasperCG’s architecture is crucial for developers working in broadcast environments. The system consists of several core components working together:

CasperCG Server: Core rendering engine built in C++
CasperCG Client: Control interface developed with Qt/C++
Flash/HTML Templates: Graphics templates for visual elements
AMCP Protocol: Advanced Media Control Protocol for system control

Key Concepts for Developers

Channels and Layers

CasperCG organizes content using a channel and layer system. Think of channels as video outputs (like different TV channels) and layers as transparent overlays stacked on top of each other:

Channel 1 (1080p50)
├── Layer 10: Video input
├── Layer 20: Lower third graphics
├── Layer 30: Logo overlay
└── Layer 40: Ticker tape

AMCP Commands

The Advanced Media Control Protocol (AMCP) is how you communicate with CasperCG. Here are essential commands every developer should know:

# Load template to channel 1, layer 20
PLAY 1-20 "my_template" [data]

# Update template data
CG 1-20 UPDATE 1 "<templateData><n>John Doe</n></templateData>"

# Remove graphics
STOP 1-20

# Clear layer
CLEAR 1-20

Template Development

Modern CasperCG primarily uses HTML templates powered by the Chromium browser engine. Here’s a basic template structure:

<!DOCTYPE html>
<html>
<head>
    <style>
        .lower-third { 
            position: absolute; 
            bottom: 100px; 
            left: 50px; 
            background: rgba(0,0,0,0.8); 
        }
    </style>
</head>
<body>
    <div class="lower-third">
        <h1 id="name">Name Here</h1>
        <p id="title">Title Here</p>
    </div>
    
    <script>
        function play() { /* Animation in */ }
        function stop() { /* Animation out */ }
        function update(data) {
            document.getElementById('name').textContent = data.name;
            document.getElementById('title').textContent = data.title;
        }
    </script>
</body>
</html>

Integration with Applications

For developers building custom applications, CasperCG offers excellent integration capabilities. Here’s how you can control CasperCG from a Node.js application:

// Node.js example using node-caspercg
const CasperCG = require('caspercg-connection');
const connection = new CasperCG();

// Connect to server
await connection.connect();

// Play lower third
await connection.play(1, 20, 'lower_third', {
    name: 'John Smith',
    title: 'Software Engineer'
});

// Update data
await connection.cgUpdate(1, 20, 1, {
    name: 'Jane Doe',
    title: 'Tech Lead'
});

// Remove graphics
await connection.stop(1, 20);

Real-World Use Cases

Sports Broadcasting

Live sports require real-time score updates and statistics. Here’s how to implement dynamic score graphics:

// Live score updates
const updateScore = (homeScore, awayScore) => {
    connection.cgUpdate(1, 25, 1, {
        home_score: homeScore,
        away_score: awayScore,
        timestamp: new Date().toISOString()
    });
};

News Production

Breaking news banners and lower thirds are staples of news broadcasting:

// Breaking news banner
const showBreakingNews = (headline) => {
    connection.play(1, 15, 'breaking_news', {
        headline: headline,
        urgency: 'high'
    });
};

Election Coverage

Election nights require complex data visualization and real-time result updates:

// Results visualization
const updateResults = (candidates) => {
    connection.cgUpdate(1, 35, 1, {
        candidates: candidates.map(c => ({
            name: c.name,
            votes: c.votes,
            percentage: (c.votes / totalVotes * 100).toFixed(1)
        }))
    });
};

Performance Optimization

When developing for broadcast environments, performance is critical. Here are key optimization strategies:

Template Optimization

GPU Acceleration: Use CSS transforms instead of changing position properties
Memory Management: Clean up unused DOM elements regularly
Animation: Prefer CSS animations over JavaScript for smoother performance
Assets: Optimize images and fonts for faster loading

Server Configuration

Proper server configuration ensures stable broadcast operations:

<configuration>
  <channels>
    <channel>
      <video-mode>1080p5000</video-mode>
      <consumers>
        <decklink>
          <device>1</device>
          <format>bgra</format>
        </decklink>
        <screen>
          <device>0</device>
        </screen>
      </consumers>
    </channel>
  </channels>
</configuration>

Integration with External Systems

Database Integration

Many broadcast applications require real-time data from databases. Here’s an example of live election results:

// Live election results from database
const updateElectionGraphics = async () => {
    const results = await db.query(`
        SELECT candidate, votes, percentage 
        FROM election_results 
        ORDER BY votes DESC
    `);
    
    await connection.cgUpdate(1, 50, 1, { results });
};

setInterval(updateElectionGraphics, 5000);

REST API Integration

Social media integration is increasingly important for modern broadcasts:

// Automated social media graphics
app.post('/api/social-post', async (req, res) => {
    const { username, content, platform } = req.body;
    
    await connection.play(1, 40, 'social_template', {
        username,
        content: content.substring(0, 280),
        platform_logo: `/assets/${platform}.png`
    });
    
    res.json({ status: 'displayed' });
});

Development Best Practices

When working with CasperCG, following these best practices will save you time and prevent issues:

Version Control: Keep templates and configurations in git repositories
Testing Environment: Set up a development CasperCG server for testing
Error Handling: Implement robust error handling for network issues
Logging: Comprehensive logging for troubleshooting broadcast issues
Backup Systems: Always have fallback graphics and procedures

Troubleshooting Common Issues

Every developer working with CasperCG will encounter these common issues:

Template Not Loading: Check file paths and CORS settings
Graphics Not Updating: Verify AMCP command syntax and timing
Performance Issues: Monitor GPU/CPU usage and optimize templates
Audio Sync Problems: Ensure frame rate matching across all inputs

Conclusion

CasperCG provides a powerful platform for broadcast graphics development. Its open-source nature, combined with robust performance and extensive customization options, makes it an excellent choice for media companies of all sizes. Whether you’re building simple lower thirds or complex data visualizations, understanding these core concepts will help you create professional broadcast graphics that enhance your productions.

The key to success with CasperCG is understanding its architecture, mastering the AMCP protocol, and building efficient templates that can handle real-time data updates. With these fundamentals in place, you’ll be well-equipped to tackle any broadcast graphics challenge.