Issue Summary

Blackmagic devices might show flickering video in Playback when first connecting to a video source. This happens while the device is retrying its format lock or when multiple apps are competing for access.

To resolve:

• Make sure Playback is the only application using the device.
• Stop/restart the stream a few times to let the device re-sync.
• Restart the Mac if the problem persists.

Once the Blackmagic device achieves a stable lock, the capture in Playback will be solid for the duration of the session.

Technical Overview

When using Blackmagic capture devices with Playback, users might experience a flickering or stuttering image when connecting to a video source. This can appear as though Playback is not working correctly, but the issue originates with how the Blackmagic hardware locks onto the input format and device access.

Playback has been tested with the following devices (via Blackmagic’s Desktop Video driver/DeckLink SDK):

• UltraStudio 4K Mini
• UltraStudio 3G Recorder + UltraStudio Monitor (combo)

⚠️ Other Blackmagic devices may also work, but only the above have been fully tested by Remoto. For the full list of supported hardware, see Blackmagic Design.

Cause

• Blackmagic devices require an exclusive hardware lock and a clean input format lock (resolution + frame rate).
• If another application (e.g., Resolve, Pro Tools, etc) is using the device, or if the signal format isn’t correctly detected on the first attempt (e.g., 1080p24 vs. 23.98), the device may display flickering video.
• Restarting capture attempts forces the device to retry syncing until it successfully latches onto the correct format. Once locked, the video feed is stable.
   

Symptoms

• Initial connection in Playback shows a flickering or unstable video feed.
• Video may stabilize after restarting the stream.
• Issue often recurs if multiple apps are accessing the device at once.

Workarounds / Troubleshooting

Step 1: Check Application Access

Make sure that only Playback is accessing the Blackmagic device. Close other video tools before starting a Playback session.

Step 2: Retry the Capture

In Playback, stop and restart the stream a few times

• This triggers the Blackmagic device to retry its format lock.
• In most cases, the video will stabilize after 2–3 attempts.
• Tip: Perform this step before admitting guests to avoid any disruptions.

Step 3: Restart the Mac (if necessary)

If video continues to flicker, the Blackmagic device may still be “held” by another app.
Restart your Mac to fully release the hardware lock and try again. 

Best Practices

• Restart the Mac before important sessions to ensure a clean device state.
• Avoid relying on auto-detect: where possible, configure your source media application to output a known, stable format.
• Keep Blackmagic Desktop Video drivers up to date to benefit from bug fixes and stability improvements.