From 92adb593c8312bde0375deedebadebd8e7cbd4fc Mon Sep 17 00:00:00 2001
From: npeter83 <npeter83+claude@gmail.com>
Date: Sun, 30 Aug 2026 20:09:00 +0200
Subject: [PATCH] fix(plex): start hls.js at position 0 for the transcode/remux
 HLS session
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Our HLS is a growing EVENT playlist with no ENDLIST, which hls.js reads as
LIVE. Its default startPosition (-1) then starts at the live edge and hugs it
(no forward buffer → rebuffer spinners), and on a resume/seek session the
segments' absolute PTS (-copyts, offset by the server's -ss) don't line up
with the live-edge timeline → 0 fragments load → permanent stall. The
seek-restart model makes fragment 0 the requested content position, so start
VOD-style at 0 and buffer forward. Fixes the transcode playback stall/rebuffer
found in 0.78.2 UAT.
---
 frontend/src/components/PlexPlayer.tsx | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/frontend/src/components/PlexPlayer.tsx b/frontend/src/components/PlexPlayer.tsx
index 4fc7663b..61124c86 100644
--- a/frontend/src/components/PlexPlayer.tsx
+++ b/frontend/src/components/PlexPlayer.tsx
@@ -261,7 +261,15 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
         hlsRef.current = null;
       }
       if (sess.mode === "hls" && Hls.isSupported()) {
-        const hls = new Hls({ maxBufferLength: 30, enableWorker: true });
+        // startPosition: 0 — our HLS is a growing EVENT playlist with no ENDLIST (see _HLS_TAIL in
+        // stream.py), which hls.js classifies as LIVE. Its default (startPosition: -1) then starts
+        // playback at the live edge and hugs it, so it never builds a forward buffer (rebuffer
+        // spinners), and on a resume/seek session the segments' absolute PTS (-copyts, offset by the
+        // server's -ss) don't line up with the live-edge timeline → 0 fragments load → permanent
+        // stall. But the seek-restart model means fragment 0 IS the requested content position
+        // (`?t=` positioned the server ffmpeg there), so we always want to start VOD-style at 0 and
+        // buffer forward up to maxBufferLength. Applies to remux + transcode alike (both use copyts).
+        const hls = new Hls({ maxBufferLength: 30, enableWorker: true, startPosition: 0 });
         hlsRef.current = hls;
         hls.loadSource(`${sess.url}?t=${Math.floor(startAt)}`);
         hls.attachMedia(video);