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fix(plex): play subtitles as WebVTT tracks (external sidecar subs no longer crash)

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Selecting a subtitle restarted the HLS session with `-map 0:s:{ord}`, assuming an
EMBEDDED stream. Films whose subs are external sidecar .srt files (Plex reports
them, but they aren't in the mkv) matched no stream; the master-playlist's
declared subtitle group then made ffmpeg fail → "Playback couldn't start".

Subtitles now go through a new GET /api/plex/subtitle/{rk}/{ord} → text/vtt
(external subs fetched from Plex via the stream key + SRT→VTT; embedded text subs
extracted with ffmpeg; image subs → 415), served as native <video><track> that
the browser overlays. So choosing/switching a subtitle is instant with NO session
restart, and stream.py drops all subtitle muxing (`-sn`, no master playlist).
Image-based subs (PGS/VobSub) are marked text=false and hidden in the picker.
Verified on prod's Nymphomaniac Vol. II: HU sidecar → 1693 WebVTT cues, no crash.
This commit is contained in:
npeter83 2026-07-06 08:45:30 +02:00
parent 335e4d7c76
commit c8c027d0fc
7 changed files with 206 additions and 89 deletions
Download patch file Download diff file Expand all files Collapse all files

14
frontend/src/lib/api.ts
View file

@ -706,7 +706,8 @@ export interface PlexItemDetail {
tagline?: string | null;
markers: PlexMarker[];
audio_streams: { ord: number; label: string; language?: string | null; default: boolean }[];
subtitle_streams: { ord: number; label: string; language?: string | null }[];
// `text`=true → offered as a WebVTT <track>; image subs (PGS/VobSub) are text=false (hidden).
subtitle_streams: { ord: number; label: string; language?: string | null; codec?: string; text: boolean }[];
status: string;
position_seconds: number;
show_title?: string | null;
@ -1152,17 +1153,14 @@ export const api = {
req(`/api/plex/show/${encodeURIComponent(id)}`),
plexItem: (id: string): Promise<PlexItemDetail> =>
req(`/api/plex/item/${encodeURIComponent(id)}`),
plexSession: (
id: string,
start = 0,
audio?: number | null,
subtitle?: number | null,
): Promise<PlexPlaySession> => {
plexSession: (id: string, start = 0, audio?: number | null): Promise<PlexPlaySession> => {
const p = new URLSearchParams({ start: String(Math.max(0, Math.floor(start))) });
if (audio != null) p.set("audio", String(audio));
if (subtitle != null) p.set("subtitle", String(subtitle));
return req(`/api/plex/stream/${encodeURIComponent(id)}/session?${p.toString()}`, { method: "POST" });
},
// WebVTT URL for a text subtitle track (used directly as a <track src>). Same-origin → cookie-authed.
plexSubtitleUrl: (id: string, ord: number): string =>
`/api/plex/subtitle/${encodeURIComponent(id)}/${ord}`,
plexProgress: (id: string, position_seconds: number, duration_seconds: number): Promise<unknown> =>
req(`/api/plex/item/${encodeURIComponent(id)}/progress`, {
method: "POST",

8
frontend/src/lib/releaseNotes.ts
View file

@ -14,6 +14,14 @@ export interface ReleaseEntry {
}
export const RELEASE_NOTES: ReleaseEntry[] = [
{
version: "0.28.3",
date: "2026-07-06",
summary: "Fix: Plex subtitles that wouldn't play — now instant, no restart.",
features: [
"Plex subtitles: fixed playback failing (\"Playback couldn't start\") when picking a subtitle on films whose subtitles are external sidecar files (very common) — those aren't inside the video, so the old approach couldn't mux them. Subtitles are now served as standalone tracks the browser overlays, so turning one on (or switching) is instant and no longer restarts the video. Image-based subtitles (Blu-ray/DVD) are hidden for now (they can't be shown as text yet).",
],
},
{
version: "0.28.2",
date: "2026-07-06",