feat: transcoding

lib/models/transcode_quality_preset.dart

@@ -0,0 +1,65 @@
+/// Video transcode quality presets modeled on Plex Web's custom-quality table.
+///
+/// When a non-[original] preset is selected, playback goes through Plex's
+/// `/video/:/transcode/universal/decision` + `start` flow. [original] bypasses
+/// transcoding entirely and uses the direct-play URL.
+enum TranscodeQualityPreset {
+  original(null, null, null),
+  p240_320(320, '420x240', 30),
+  p320_720(720, '576x320', 40),
+  p480_1_5mbps(1500, '720x480', 60),
+  p720_2mbps(2000, '1280x720', 60),
+  p720_3mbps(3000, '1280x720', 75),
+  p720_4mbps(4000, '1280x720', 100),
+  p1080_8mbps(8000, '1920x1080', 60),
+  p1080_10mbps(10000, '1920x1080', 75),
+  p1080_12mbps(12000, '1920x1080', 90),
+  p1080_20mbps(20000, '1920x1080', 100);
+
+  const TranscodeQualityPreset(this.videoBitrateKbps, this.videoResolution, this.videoQuality);
+
+  final int? videoBitrateKbps;
+  final String? videoResolution;
+  final int? videoQuality;
+
+  bool get isOriginal => this == TranscodeQualityPreset.original;
+
+  String get storageKey => name;
+
+  static TranscodeQualityPreset fromStorage(String? stored) {
+    if (stored == null) return TranscodeQualityPreset.original;
+    for (final v in TranscodeQualityPreset.values) {
+      if (v.name == stored) return v;
+    }
+    return TranscodeQualityPreset.original;
+  }
+
+  /// Resolution height (e.g. 720, 1080) parsed from [videoResolution]. Null for original.
+  int? get resolutionHeight {
+    final r = videoResolution;
+    if (r == null) return null;
+    final parts = r.split('x');
+    if (parts.length != 2) return null;
+    return int.tryParse(parts[1]);
+  }
+
+  /// Order shared by every picker surface so they can't drift apart:
+  /// [original] pinned first, then transcode presets highest-bitrate first.
+  static final List<TranscodeQualityPreset> displayOrder = List.unmodifiable([
+    original,
+    ...values.where((p) => !p.isOriginal).toList().reversed,
+  ]);
+}
+
+/// Outcome of a transcode decision call.
+enum TranscodeDecisionOutcome {
+  /// Decision indicates transcode is available (`transcodeDecisionCode == 1001`).
+  transcodeOk,
+
+  /// Decision indicates only direct play is available (`transcodeDecisionCode == 1000`).
+  /// Caller should fall back to the direct-play URL.
+  directPlayOnly,
+
+  /// Decision failed (HTTP error, code >= 2000, or parse error).
+  failed,
+}