Possible causes
- The client cannot Direct Play the container or a stream.
- Subtitle selection forces remuxing or video transcoding.
Check in this order
- Read the server playback reason.
- Disable subtitles for one comparison test.
- Compare the same file on a second client.
Fix steps
- Change only the stream named by the server playback reason.
- Use a client-supported subtitle mode when subtitle burning triggers video transcoding.
When to escalate
Escalate when the server reason contradicts the official client codec table for the recorded versions.
If it is still unresolved, collect
- server version
- client
- transcode reason
- selected subtitles
- selected audio
Known log signatures
transcode reason | container not supported | video codec not supported | subtitle burn
Evidence
- Plex supported media formats — checked 2026-07-12, review due 2026-10-10
- Jellyfin codec support — checked 2026-07-12, review due 2026-10-10