Subtitle style settings (background/color) not applied to embedded subtitle tracks

[P1oNerd]

Installation type

Flatpak (.flatpak)

Version

1.0.3

Platform

Ubuntu 24.04 (noble)

Desktop Environment

GNOME

Windowing System

wayland

GPU

AMD Radeon Graphics (Renoir APU) - radeonsi/Mesa 25.2.8

Describe the bug

Global subtitle style settings (background opacity, text color) configured
in Settings > Subtitles are applied correctly to external subtitles
(fetched via addons like OpenSubtitles), but are NOT applied when an
embedded subtitle track (extracted from the video file itself) is selected.
Embedded subtitles render with default/no styling instead of the
user-configured black background + white text.

To Reproduce

1. Play a video file that contains an embedded subtitle track (e.g. MKV
   with embedded SRT/ASS)
2. Go to Settings > Subtitles, set Background to opaque black and Text
   color to white
3. Select the embedded subtitle track from the subtitle menu
4. Observe: styling is not applied, subtitles render without the
   configured background box
5. For comparison, select an external subtitle (via an addon) for the
   same video — styling IS applied correctly here

Expected behavior
Subtitle style settings should apply uniformly regardless of whether the
active track is embedded or external.

Additional context
This may relate to embedded tracks being rendered natively via libmpv
while external tracks go through a different overlay layer, so style
overrides may only reach one code path. A related report describing the
same embedded-vs-external inconsistency (on Windows) exists at
Stremio/stremio-bugs#2286.

Logs

ERROR stremio_linux_shell::app::ipc: Failed to convert IpcEvent to IpcMessageRequest: Invalid method: mpv-set-gpu-video-processing
WARN stremio_linux_shell::app::video: Failed to set property vo: Unsupported

[tymmesyde]

Hi, you probably need to enable the "Style ASS subtitles" setting under Player -> Advanced