Quick Summary (TL;DR)
When using EasyWorship Alpha Key outputs with HDMI-to-SDI converters and a Blackmagic ATEM, the key (transparency matte) and fill (graphics) can drift out of sync. This causes flicker, ghosting, or broken overlays. Fix it by using either Decimator MD-HX units in reference/follower mode or Blackmagic converters with an external sync generator. Proper sync ensures clean, artifact-free overlays in church production and streaming.
Introduction and Overview
This is the fourth article in our 4-part series on EasyWorship Alpha Key workflows for church production and live streaming. In Part 2, we explained why HDMI should be converted to SDI. In Part 3, we fixed transparency issues by aligning GPU color output with broadcast standards. In this article, we’ll look at frame synchronization; keeping your key and fill outputs perfectly aligned.
The Synchronization Problem
Key/fill overlays depend on two signals arriving in perfect alignment. Without sync, you may see:
- Flickering edges around text
- Ghosting or shadows during transitions
- Semi-broken overlays where matte and fill are offset by a frame
This happens because converters process signals independently. Without a common timing reference (known in broadcast as genlock), they can drift slightly apart.
Key and fill displaying as intended
Slight artifacting showing the previous slide’s text
Why Sync Matters in Worship Production
- Lyrics overlays during worship songs must remain crisp and stable for the congregation.
- Sermon points and scripture slides projected on IMAG or streams need readability without jitter.
- Live streaming requires consistency, out-of-sync overlays look unprofessional and distracting.
Industry Standard Solutions
Professional video production uses one of three approaches:
- Sync Generators (Genlock): Devices that output black burst or tri-level sync to keep all gear aligned.
- Frame Synchronizers: Some mixers (like higher-end ATEM models) include built-in frame sync.
- Converter-Based Sync (Decimator): Certain converters (e.g., MD-HX) can be linked together to stay frame accurate.
How to Sync with Decimator MD-HX
The Decimator MD-HX has an internal scaler and reference system. To sync:
- Connect Fill HDMI from EasyWorship to the first Decimator (Reference unit).
- Connect Key HDMI to a second Decimator (Follower unit).
- On the Reference unit, set Reference = Freerun.
- Run SDI Out from Reference → SDI In on Follower.
- On the Follower, set Reference = SDI In.
- Route both signals through their scalers for consistent sync.
This locks both converters together, ensuring key and fill frames align perfectly.
How to Sync with Blackmagic Converters
Blackmagic’s Up/Down Cross Converters don’t internally sync with each other, so you’ll need an external sync generator (~$200):
- Connect reference outputs from the sync generator to each converter’s Ref In.
- Configure DIP switches to match resolution and frame rate.
- Ensure the Blackmagic ATEM mixer also references the same sync generator.
- Run HDMI-to-SDI through each converter as usual.
This ensures all devices share the same timing reference.
Cost & Setup Comparison
| Solution | Hardware | Cost | Ease of Setup | Best For |
|---|---|---|---|---|
| Decimator | 2 × MD-HX | ~$600 | Easy, menu-based control | Teams wanting simplicity |
| Blackmagic | 2 × Up/Down Cross + Sync Generator | ~$500 | Budget-friendly, but more complex | Teams comfortable with DIP switches |
Troubleshooting Out-of-Sync Key/Fill
If your overlays don’t look right, check for these symptoms:
- Edges flicker during transitions
- Overlays ghost or shimmer slightly
- Lower thirds break for a frame during motion
Fix: Reconfirm sync settings (Decimator reference/follower or Blackmagic + sync generator) and ensure your mixer references the same source.
Real-World Case Study: Church in Orlando
At a large conference in Orlando, a worship production team ran EasyWorship overlays across massive LED walls. They used two HDMI outputs from the EasyWorship PC (one for key and one for fill) each converted to SDI. Initially, they struggled with ghosting and flickering text during fast worship transitions. The issue was traced back to unsynced converters. By configuring two Decimator MD-HX units in reference/follower mode, they locked key and fill in perfect sync. The result: clean, crisp overlays that scaled beautifully on the LED wall, with no distracting artifacts for thousands of attendees.
This example highlights why syncing key and fill isn’t optional, it’s essential for professional, distraction-free worship visuals.
Quick Fix Checklist
- For Decimator: set Reference = Freerun, Follower = SDI In
- For Blackmagic: add an external sync generator
- Test with moving overlays to confirm alignment
- Use scopes or monitor outputs for visual confirmation
Key Takeaways
- Out-of-sync key/fill = flicker, ghosting, and broken overlays.
- Decimator MD-HX: higher cost, easier setup with internal reference/follower sync.
- Blackmagic converters: lower cost, require external sync generator.
- Proper sync ensures worship overlays remain crisp and professional.
Wrap Up
This concludes our 4-part series on EasyWorship Alpha Key workflows. By converting HDMI to SDI (Part 2), fixing transparency issues (Part 3), and syncing key/fill outputs (Part 4), you can achieve broadcast-quality overlays in your worship services. Whether projecting lyrics in-house or streaming sermons online, synced, clean overlays keep your content distraction-free and professional.
Final Note: EasyWorship makes it easy for churches to deliver professional key and fill outputs. With proper sync and HDMI-to-SDI conversion, your production team can create overlays that look just as polished as professional broadcast environments.
