Screen sharing forces ultrawide sources into a 16:9 feed with grey letterboxing

Summary

When sharing content with a non-16:9 aspect ratio, Fluxer presents the stream inside a fixed 16:9 video feed. For example, sharing a game running at 21:9 or sharing an entire ultrawide display results in grey bars above and below the captured content. The source aspect ratio is not preserved in the final video feed. I reproduced this on both a self-hosted Fluxer instance and the official hosted Fluxer service. I also tested it using two separate clients, which both displayed the same behavior.

Steps to reproduce

1. Use a monitor with a 21:9 aspect ratio.
2. Join a voice call.
3. Start screen sharing.
4. Share either:
   • A game running at 21:9; or
   • The entire ultrawide display.
5. View the stream from another client.
6. Observe that the stream is presented as a 16:9 feed with grey bars above and below the 21:9 content.

Environment

Reproduced on both the official hosted service and a self-hosted instance. Clients tested:

• Stable Web 2026.806.190827
• Canary Desktop 2026.602.31138
• Canary Web 2026.605.11941