Troubleshooting & FAQ
Key quality
| What you see | Likely cause | Fix |
|---|---|---|
| Patches of green or blue stay in the background | Similarity is too low | Raise Similarity in small steps (about 0.005–0.01). Check that the key colour matches the real screen colour (use Pick Color or Autotune). Check the screen lighting. |
| Holes or see-through areas in the presenter | Similarity is too high, so parts of the skin or clothing match the key colour | Lower Similarity step by step. Make sure the presenter isn't wearing anything in the key colour. |
| Jagged, hard edges | Blend is too low | Raise Blend slightly, in small steps. |
| A see-through halo around the presenter | Blend is too high | Lower Blend in small steps. |
| Green or blue tint on skin, hair and edges | Spill: screen light reflecting onto the presenter | Turn on Despill, set the type to match the screen, and raise Mix, or start from Green kit / Blue kit. On set, move the presenter further from the screen and add a rim light. |
| Skin looks pink or magenta | Despill is too strong | Lower Mix in small steps. A little green on the edges looks better than magenta skin. |
| Edges flicker during movement | Similarity is right at the border, so edge pixels switch between visible and removed | Move Similarity clearly up or down, and raise Blend slightly. |
Stream not updating after Apply
What you see: you clicked Apply Now, but the live output still shows the old background, overlay or settings.
Why: a running ingest can keep using its previous configuration until it restarts.
Fix:
- Check the output's card: ● Needs Apply means the change hasn't been saved yet. Apply saves the key settings and every output's background and overlay, whichever output is on-air.
- Check that Stop & unlock after Apply is on (it is by default), then apply again. Or click Bounce.
- If the output still doesn't update, stop and restart the broadcast in your encoder.
Stop & unlock and Bounce restart the ingest and briefly interrupt the stream. Key, despill, EQ and overlay position changes don't need a restart: in Live mode they apply in real time.
Player shows a black screen
- Look at the signal strip on the ingest card. Waiting for signal (red) means nothing is arriving: check that your encoder uses the Server and Stream Key from the ingest card. Where do I publish? → takes you there.
- Check the server in your encoder: it must be
rtmp://bintu-studio.nanocosmos.de/live. Another RTMP server can accept your stream without starting the chroma key, so the outputs stay black even though the ingest is live. - Make sure your encoder publishes to the ingest, not to an output. An output's Output name isn't a publish target.
- Check that playback isn't paused (click Start playback).
- In Live, click Ingest. If the raw feed doesn't play, the problem is the encoder or ingest, not the chroma key.
FAQ
My output shows the wrong background. How do I change it?
You can do this yourself:
- Upload the correct file in Backgrounds (MP4, PNG or JPG, at your camera's resolution).
- In Stream Setup, load your setup if it isn't open, and choose the new file in that output's Background field. Each output has its own background, so make sure you change the right one.
- Click Apply Now (the card shows ● Needs Apply until you do). If the old background is still showing, see Stream not updating after Apply.
If you contact support, include the ingest stream ID and the filename you expect.
My background looks stretched, zoomed or has black bars
The background's resolution or aspect ratio doesn't match your camera. Export it at the same size as your source (1920×1080 or 1280×720, 16:9), upload it again and re-apply.
My MP4 background was rejected, or shows a ⚠ warning
The uploader checks each MP4's average bitrate. Files above 8 Mbps get a ⚠ warning, and files above 15 Mbps are rejected. All outputs share one processing job, so a heavy background can take every output offline. Re-encode the file as H.264 at 3–5 Mbps (no more than 8 Mbps), at 720p or 1080p, and upload it again. See Prepare MP4 backgrounds for the recommended settings.
All my outputs went offline or started stuttering after I changed a background
A background with a very high bitrate can overload the processing job that renders all your outputs. Check whether the background has a ⚠ or ✕ badge in Backgrounds, or an amber or red border on its Background field. If it does, switch that output back to a lighter background, re-encode the heavy file (see Prepare MP4 backgrounds) and apply again.
I uploaded a file but it isn't in the background list
- Format: only MP4, PNG and JPG are accepted. MOV, MKV and GIF won't appear.
- Bitrate: MP4s above 15 Mbps are rejected and not uploaded. See the question above.
- Refresh: click Refresh in the file list, or reopen the dropdown.
- Upload finished: the file must be listed in Backgrounds, with its size, before you can assign it.
Can each output have a different background or logo?
Yes. Each output has its own background, overlay, tags and transcodes. Overlays are all-or-none: every output needs an overlay for overlays to appear, but each can be a different PNG. See Outputs & Branding.
What format and resolution should backgrounds be?
- Moving backgrounds: MP4, ideally a short, seamless loop at about 3–5 Mbps
- Stills: PNG or JPG
- Overlays: PNG with transparency
- Resolution: the same as your camera, 1920×1080 or 1280×720 (16:9)
Can I use a live stream as a background?
Yes. Type the stream name or stream ID of another nanoStream stream in the Background field. That stream must be live.
Can I reuse a setup instead of configuring everything again?
Yes. In Stream Setup, choose Reuse existing setup, paste the ingest stream ID (or its Dashboard URL) and click Load Existing Setup. The key settings, targets, backgrounds and overlays are restored. See Reuse an existing setup.
How do I know my key is good enough to go live?
Look for clean edges, no colour tint on the presenter, a background with no leftover screen colour, and a natural look. Have the presenter move around, and check the edges against a bright, contrasting background. See Check your key.
Still stuck?
Contact nanocosmos support. Include your ingest stream ID, which output is affected, and a screenshot of the problem.