Camera Switching for XR/LED Workflows: A Practical Guide

The Challenge

In multi-camera XR productions using LED volumes, only one camera perspective can be correctly displayed on the LED wall at any given time. This creates an inherent challenge: how do you handle multiple cameras while maintaining visual quality?

Traditional Solution: Frame Remapping

The industry standard approach, known as frame remapping (or GhostFrame/interleaving), displays multiple perspectives within a single frame by leveraging high LED refresh rates. Each camera is synchronized to see only its designated perspective.

Limitations of Frame Remapping

1. Resource Intensive: Each camera perspective requires its own complete render engine setup. For example:

   • Small setup (3 cameras, 1 render engine per perspective): 3 total engines needed

   • Large setup (5 cameras, 5 render engines per perspective): 25 total engines needed

2. Technical Constraints:

   • Reduced camera shutter time

   • Increased lighting requirements

   • Complex timing synchronization

   • Limited by LED panel and processor capabilities

The Better Way: Camera Switching for LED Workflows

How It Works

Instead of rendering multiple perspectives simultaneously, we dynamically switch the camera tracking input to match the active camera. This ensures the LED wall always displays the correct perspective for the current shot.

Key Benefits

• Requires only one set of render engines regardless of camera count

• Works with a broader range of LED panels and processors

• Simpler technical setup

• More efficient resource utilization

Current Limitations

• No camera preview before switching

• Traditional vision mixer cutting not possible

  • All cuts must be made through the Camera Switching system

Set Extension Integration

For setups where cameras see beyond the LED volume (virtual set extension):

Standard Approach

• One render engine per camera for set extensions

• Additional engines for LED volume

Optimized Approach

• Single render engine with synchronized switching

• Handles both video and camera tracking inputs

• Seamlessly coordinates LED and set extension switching

Technical Requirements

Perfect Synchronization

Three elements must be precisely synchronized:

1. LED processor display timing

2. Camera capture timing

3. Render engine switching

Hardware Requirements

1. LED Processor:

   • Must display full progressive frames

   • Requires common lock/genlock signal aligned with cameras

   • May need sync offset adjustment

2. Cameras:

   • Progressive frame capture

   • Global shutter to guarantee perfect cut, a very fast rolling shutter could work

   • Synchronized to common reference signal

   • Individual camera sync adjustment capability

3. Render Engines:

   • Common sync signal with LED processor and cameras

   • Shared LTC timecode signal for coordination

   • Synchronized switching capability