Subtitle background not rendering despite non-zero background opacity #773
Description
Bug Description
Subtitle background does not appear even when the background opacity is set to a high value. The setting appears to have no visual effect across platforms.
The subtitle text renders correctly, and other styling options like font size, color, and border are applied, but the background box behind subtitles is missing entirely.
Steps to Reproduce
- Go to Settings → Subtitle Styling
- Set Background Opacity to a high value (e.g., 80 to 100 percent)
- Play any video with subtitles enabled
- Observe subtitle rendering
Expected Behavior
Subtitles should display with a visible background box behind the text, with opacity matching the configured value.
Actual Behavior
No background is rendered behind subtitles, regardless of opacity setting. The subtitles appear as plain text with outline only.
Plezy Version
1.30.0
Platform
iOS, Windows, Android TV
Device Information
iPhone 14 Pro, Windows 11, FireTV (assume its broken on all platforms)
Logs and Stack Traces
Logs
// set the caption properties (high background opacity)
[18:09:02.871] [INFO] [MPV:cplayer] Set property: sub-font-size="38" -> 1
[18:09:02.873] [INFO] [MPV:cplayer] Set property: sub-color="#FFFFFF" -> 1
[18:09:02.874] [INFO] [MPV:cplayer] Set property: sub-outline-size="1" -> 1
[18:09:02.874] [INFO] [MPV:cplayer] Set property: sub-border-size="1" -> 1
[18:09:02.874] [INFO] [MPV:cplayer] Set property: sub-outline-color="#000000" -> 1
[18:09:02.875] [INFO] [MPV:cplayer] Set property: sub-border-color="#000000" -> 1
[18:09:02.876] [INFO] [MPV:cplayer] Set property: sub-back-color="#E5000000" -> 1
[18:09:02.876] [INFO] [MPV:cplayer] Set property: sub-ass-override="no" -> 1
[18:09:02.878] [INFO] [MPV:cplayer] Set property: sub-ass-video-aspect-override="1" -> 1
[18:09:02.879] [INFO] [MPV:cplayer] Set property: sub-pos="100" -> 1
// loading media
[18:09:06.274] [INFO] [MPV:cplayer] Running hook: ytdl_hook/on_preloaded
[18:09:06.275] [INFO] [MPV:cplayer] Set property: aid="1" -> 1
[18:09:06.275] [INFO] [MPV:cplayer] Set property: sid="1" -> 1
[18:09:06.275] [INFO] [MPV:mkv] select track 0
[18:09:06.275] [INFO] [MPV:mkv] select track 1
[18:09:06.275] [INFO] [MPV:mkv] select track 2
[18:09:06.276] [INFO] [MPV:cplayer] ● Video --vid=1 (hevc 1916x1080 23.976 fps) [default]
[18:09:06.276] [INFO] [MPV:cplayer] ● Audio --aid=1 --alang=eng 'Surround' (eac3 6ch 48000 Hz) [default]
[18:09:06.276] [INFO] [MPV:cplayer] ● Subs --sid=1 --slang=eng (ass)
[18:09:06.276] [INFO] [MPV:cplayer] ○ Subs --sid=2 --slang=eng (ass)
// loading subtitle fonts
[18:09:06.438] [INFO] [MPV:sub/ass] libass API version: 0x1704000
[18:09:06.438] [INFO] [MPV:sub/ass] libass source: meson, commit: 0.17.4-20-gcbb743215bad0fe202477e569fe8005545258ccd
[18:09:06.440] [INFO] [MPV:sub/ass] Shaper: FriBidi 1.0.16 (SIMPLE) HarfBuzz-ng 12.3.0 (COMPLEX)
[18:09:06.440] [INFO] [MPV:sub/ass] Setting up fonts...
[18:09:06.441] [INFO] [MPV:sub/ass] Loading font file '%AppDataLocal%\subtitle_fonts\go-noto-current-regular.ttf'
[18:09:06.463] [INFO] [MPV:sub/ass] Using font provider directwrite (with GDI)
[18:09:06.464] [INFO] [MPV:sub/ass] Done.
[18:09:06.464] [INFO] [MPV:cplayer] Starting playback...
[18:09:11.860] [INFO] [MPV:sub/ass] fontselect: (sans-serif, 400, 0) -> ArialMT, 0, ArialMT
[18:09:11.867] [INFO] [MPV:sub/ass] mangling colors like vsfilter: RGB -> bt.601 limited -> bt.709 bt.601 -> RGB
Screenshots
Subtitle styling settings show background opacity set to ~85%
Video playback shows subtitles without any background box
Additional Context
No response