feat(plex): migrate video transcoding to HLS

lib/utils/codec_utils.dart

@@ -43,9 +43,9 @@ class CodecUtils {
     };
   }
 
-  /// Image-based (bitmap) subtitle codecs. These can't be converted to text;
-  /// during an HTTP/MKV transcode Plex copies the stream into the container and
-  /// the player renders it natively.
+  /// Image-based (bitmap) subtitle codecs. Plex burns these into the video
+  /// when the selected output transport cannot carry a bitmap subtitle
+  /// rendition.
   static bool isImageSubtitleCodec(String? codec) {
     if (codec == null) return false;
     return switch (codec.toLowerCase()) {
@@ -61,10 +61,9 @@ class CodecUtils {
     };
   }
 
-  /// Subtitle codecs that can be carried inside the HTTP/MKV transcode stream
-  /// (`subtitles=embedded`): text codecs plus the image codecs the MKV target
-  /// supports. Keyed sidecars are delivered separately and are not covered here.
-  static bool isEmbeddableSubtitleCodec(String? codec) {
+  /// Subtitle codecs Plex can deliver in a transcode. Text codecs can become
+  /// segmented HLS WebVTT; image codecs can be burned into the video.
+  static bool isTranscodableSubtitleCodec(String? codec) {
     return isTextSubtitleCodec(codec) || isImageSubtitleCodec(codec);
   }
 

lib/utils/player_utils.dart

@@ -1,11 +1,6 @@
 import '../mpv/mpv.dart';
 
 const restartBeforePreviousItemThreshold = Duration(seconds: 3);
-const plexTranscodeSeekRangeStartTolerance = Duration(milliseconds: 500);
-const plexTranscodeSeekRangeEndGuard = Duration(milliseconds: 500);
-const plexTranscodeSeekNoopTolerance = Duration(seconds: 1);
-
-enum PlexTranscodeSeekAction { nativeSeek, restartTranscode }
 
 bool shouldRestartBeforePreviousItem(Duration position) {
   return position > restartBeforePreviousItemThreshold;
@@ -17,40 +12,3 @@ Duration clampSeekPosition(Player player, Duration position) {
   if (duration > Duration.zero && position > duration) return duration;
   return position;
 }
-
-/// Plex MKV-over-HTTP transcodes are only native-seeked inside ranges the
-/// player reports as locally seekable. Anything outside those ranges needs a
-/// server-offset transcode restart.
-PlexTranscodeSeekAction resolvePlexTranscodeSeekAction({
-  required Duration currentPosition,
-  required Duration target,
-  required List<BufferRange> bufferRanges,
-  bool allowBufferedNativeSeek = true,
-  Duration rangeStartTolerance = plexTranscodeSeekRangeStartTolerance,
-  Duration rangeEndGuard = plexTranscodeSeekRangeEndGuard,
-  Duration noopTolerance = plexTranscodeSeekNoopTolerance,
-}) {
-  final validRanges = bufferRanges.where((range) => range.end >= range.start).toList();
-  if (allowBufferedNativeSeek &&
-      _isInAnyBufferedSeekRange(target, validRanges, startTolerance: rangeStartTolerance, endGuard: rangeEndGuard)) {
-    return PlexTranscodeSeekAction.nativeSeek;
-  }
-
-  if ((target - currentPosition).abs() <= noopTolerance) {
-    return PlexTranscodeSeekAction.nativeSeek;
-  }
-
-  return PlexTranscodeSeekAction.restartTranscode;
-}
-
-bool _isInAnyBufferedSeekRange(
-  Duration target,
-  List<BufferRange> ranges, {
-  required Duration startTolerance,
-  required Duration endGuard,
-}) {
-  for (final range in ranges) {
-    if (target >= range.start - startTolerance && target <= range.end - endGuard) return true;
-  }
-  return false;
-}