Fix subtitle seeks in Movie player

Prevent the Movie player from showing subtitles that were already in progress when playback seeks, for both plain cues and ASS rendering. The change also keeps the last valid ASS overlay geometry until video dimensions are available again, avoiding subtitle misalignment over letterboxing during seek/transcode reloads.

src/web/Movie/embedded.html

@@ -913,6 +913,7 @@ function transcodeSeekTo(seconds) {
     if (transcodeDuration > 0) { pos = Math.min(transcodeDuration, pos); }
 
     showSeekFreeze();
+    setSubtitleSeekFloor(pos);
     transcodeSeekOffset = pos;
     vid.src = TRANSCODE_API + '?file=' + encodeURIComponent(currentFile.filepath)
             + '&start=' + pos.toFixed(3);
@@ -1024,6 +1025,9 @@ function initVideoControls() {
     // Drop the transcode-seek freeze frame the moment the new segment is live.
     // 'playing' is the accurate signal; 'loadeddata' covers a seek made while
     // paused (where 'playing' never fires), and 'error' avoids a stuck overlay.
+    // Any seek — native or transcode reload — re-bases the subtitle floor
+    $(vid).on('seeking', function () { setSubtitleSeekFloor(effectivePlaybackTime()); });
+
     $(vid).on('playing', hideSeekFreeze);
     $(vid).on('loadeddata', function () { if (vid.paused) { hideSeekFreeze(); } });
     $(vid).on('error', hideSeekFreeze);
@@ -1477,6 +1481,7 @@ function updateSubtitleDisplay() {
     var cues  = loadedSubtitleFiles[activeSubtitleIndex].cues;
     var found = null;
     for (var i = 0; i < cues.length; i++) {
+        if (cues[i].start < subtitleSeekFloor) { continue; }   // in flight when we landed
         if (currentTime >= cues[i].start && currentTime <= cues[i].end) { found = cues[i]; break; }
     }
     if (found) {
@@ -1624,6 +1629,20 @@ function applyActiveSubtitle() {
     }
 }
 
+// ── Subtitle seek floor ──────────────────────────────────────────────────────
+// After a seek, any line that had already begun before the landing point is
+// skipped entirely; only lines that start at or after it are shown. Seeking to
+// 1:02 with lines at 1:00-1:03 and 1:05-1:10 therefore shows nothing until 1:05.
+var subtitleSeekFloor = 0;
+
+function setSubtitleSeekFloor(time) {
+    subtitleSeekFloor = Math.max(0, time || 0);
+    if (assRenderer) { assRenderer.setSuppressBefore(subtitleSeekFloor); }
+    updateSubtitleDisplay();
+}
+
+function resetSubtitleSeekFloor() { setSubtitleSeekFloor(0); }
+
 // ── Styled ASS rendering ─────────────────────────────────────────────────────
 // ASS tracks are fetched in their native form and drawn by script/ass.js, which
 // preserves per-line styling and position. That is what makes dual-language
@@ -1647,14 +1666,17 @@ function syncAssOverlayGeometry() {
     var cw = vid.clientWidth, ch = vid.clientHeight;
     var vw = vid.videoWidth, vh = vid.videoHeight;
 
-    var left = 0, top = 0, width = cw, height = ch;
-    if (vw > 0 && vh > 0 && cw > 0 && ch > 0) {
-        var scale = Math.min(cw / vw, ch / vh);
-        width  = vw * scale;
-        height = vh * scale;
-        left   = (cw - width) / 2;
-        top    = (ch - height) / 2;
-    }
+    // Until the decoder reports the picture size there is no way to know where
+    // the letterbox bars are. Falling back to the raw element box would scale
+    // the script against the black bars too and push bottom-anchored lines down
+    // over the controls, so keep the last known good geometry instead.
+    if (!(vw > 0 && vh > 0 && cw > 0 && ch > 0)) { return; }
+
+    var scale  = Math.min(cw / vw, ch / vh);
+    var width  = vw * scale;
+    var height = vh * scale;
+    var left   = (cw - width) / 2;
+    var top    = (ch - height) / 2;
     if (overlay._w !== width || overlay._h !== height || overlay._l !== left || overlay._t !== top) {
         overlay._w = width; overlay._h = height; overlay._l = left; overlay._t = top;
         overlay.style.left   = left + 'px';
@@ -1950,6 +1972,7 @@ function initMain(){
     initSettingsPopup();
     initScrubPreview();
     initAssRenderer();
+    resetSubtitleSeekFloor();   // a freshly opened file starts unsuppressed
     if (currentFile) {
         scheduleStoryboardLoad(currentFile.filepath);
         loadEmbeddedTrackList(currentFile.filepath);

src/web/Movie/index.html

@@ -2529,6 +2529,7 @@ function transcodeSeekTo(seconds) {
     if (transcodeDuration > 0) { pos = Math.min(transcodeDuration, pos); }
 
     showSeekFreeze();
+    setSubtitleSeekFloor(pos);
     transcodeSeekOffset = pos;
     vid.src = TRANSCODE_API + '?file='
             + encodeURIComponent(currentEpisodes[playingIndex].filepath)
@@ -3356,6 +3357,7 @@ function isWebPlayable(ext) {
 function startPlayback(index) {
     cancelCountdown();
     hideSeekFreeze();   // never carry a frozen frame across to a different episode
+    resetSubtitleSeekFloor();   // a fresh episode starts unsuppressed
     $('#resume-popup').removeClass('active');
     if (!currentEpisodes || currentEpisodes.length === 0) { return; }
     playingIndex = index;
@@ -3654,6 +3656,9 @@ function initVideoControls() {
     // Drop the transcode-seek freeze frame the moment the new segment is live.
     // 'playing' is the accurate signal; 'loadeddata' covers a seek made while
     // paused (where 'playing' never fires), and 'error' avoids a stuck overlay.
+    // Any seek — native or transcode reload — re-bases the subtitle floor
+    $(vid).on('seeking', function () { setSubtitleSeekFloor(effectivePlaybackTime()); });
+
     $(vid).on('playing', hideSeekFreeze);
     $(vid).on('loadeddata', function () { if (vid.paused) { hideSeekFreeze(); } });
     $(vid).on('error', hideSeekFreeze);
@@ -4412,6 +4417,7 @@ function updateSubtitleDisplay() {
     var cues = loadedSubtitleFiles[activeSubtitleIndex].cues;
     var found = null;
     for (var i = 0; i < cues.length; i++) {
+        if (cues[i].start < subtitleSeekFloor) { continue; }   // in flight when we landed
         if (currentTime >= cues[i].start && currentTime <= cues[i].end) {
             found = cues[i]; break;
         }
@@ -4561,6 +4567,20 @@ function applyActiveSubtitle() {
     }
 }
 
+// ─── Subtitle seek floor ──────────────────────────────────────────────────────
+// After a seek, any line that had already begun before the landing point is
+// skipped entirely; only lines that start at or after it are shown. Seeking to
+// 1:02 with lines at 1:00-1:03 and 1:05-1:10 therefore shows nothing until 1:05.
+var subtitleSeekFloor = 0;
+
+function setSubtitleSeekFloor(time) {
+    subtitleSeekFloor = Math.max(0, time || 0);
+    if (assRenderer) { assRenderer.setSuppressBefore(subtitleSeekFloor); }
+    updateSubtitleDisplay();
+}
+
+function resetSubtitleSeekFloor() { setSubtitleSeekFloor(0); }
+
 // ─── Styled ASS rendering ─────────────────────────────────────────────────────
 // ASS tracks are fetched in their native form and drawn by script/ass.js, which
 // preserves per-line styling and position. That is what makes dual-language
@@ -4584,14 +4604,17 @@ function syncAssOverlayGeometry() {
     var cw = vid.clientWidth, ch = vid.clientHeight;
     var vw = vid.videoWidth, vh = vid.videoHeight;
 
-    var left = 0, top = 0, width = cw, height = ch;
-    if (vw > 0 && vh > 0 && cw > 0 && ch > 0) {
-        var scale = Math.min(cw / vw, ch / vh);
-        width  = vw * scale;
-        height = vh * scale;
-        left   = (cw - width) / 2;
-        top    = (ch - height) / 2;
-    }
+    // Until the decoder reports the picture size there is no way to know where
+    // the letterbox bars are. Falling back to the raw element box would scale
+    // the script against the black bars too and push bottom-anchored lines down
+    // over the controls, so keep the last known good geometry instead.
+    if (!(vw > 0 && vh > 0 && cw > 0 && ch > 0)) { return; }
+
+    var scale  = Math.min(cw / vw, ch / vh);
+    var width  = vw * scale;
+    var height = vh * scale;
+    var left   = (cw - width) / 2;
+    var top    = (ch - height) / 2;
     if (overlay._w !== width || overlay._h !== height || overlay._l !== left || overlay._t !== top) {
         overlay._w = width; overlay._h = height; overlay._l = left; overlay._t = top;
         overlay.style.left   = left + 'px';

src/web/Movie/script/ass.js

@@ -413,6 +413,7 @@ function Renderer(overlay) {
     this.height = 0;
     this.scale = 1;
     this._lastKey = null;
+    this._suppressBefore = 0;
 }
 
 Renderer.prototype.setTrack = function (track) {
@@ -437,12 +438,28 @@ Renderer.prototype.clear = function () {
     this._lastKey = null;
 };
 
+/**
+ * Ignore any line that had already begun before `time`.
+ *
+ * Seeking into the middle of a line would otherwise drop the viewer into a
+ * half-shown caption. Everything already in flight at the landing point is
+ * skipped; the next line to *begin* after it plays normally.
+ */
+Renderer.prototype.setSuppressBefore = function (time) {
+    this._suppressBefore = Math.max(0, time || 0);
+    this._lastKey = null;   // rebuild now so a suppressed line disappears at once
+};
+
 Renderer.prototype.activeEvents = function (time) {
     var out = [];
     if (!this.track) { return out; }
+    var floor = this._suppressBefore || 0;
     var events = this.track.events;
     for (var i = 0; i < events.length; i++) {
-        if (time >= events[i].start && time <= events[i].end) { out.push(events[i]); }
+        var ev = events[i];
+        if (time < ev.start || time > ev.end) { continue; }
+        if (ev.start < floor) { continue; }   // was already on screen when we landed
+        out.push(ev);
     }
     return out;
 };