[video_player] Fixes mechanism to detect identifier in multiline WebV…

…TT captions (#8555) In order to play WebVTT captions which include multiple lines the detection must be changed, as captions don't necessarily have an identifier, when they are longer than two lines.
flutter · Feb 21, 2025 · a135dc6 · a135dc6
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diff --git a/packages/video_player/video_player/CHANGELOG.md b/packages/video_player/video_player/CHANGELOG.md
@@ -1,6 +1,7 @@
-## NEXT
+## 2.9.3
 
 * Updates minimum supported SDK version to Flutter 3.22/Dart 3.4.
+* Fixes mechanism to detect identifier in multi-line WebVTT captions.
 
 ## 2.9.2
 

diff --git a/packages/video_player/video_player/lib/src/web_vtt.dart b/packages/video_player/video_player/lib/src/web_vtt.dart
@@ -49,8 +49,9 @@ List<Caption> _parseCaptionsFromWebVTTString(String file) {
       continue;
     }
 
-    // Caption has header
-    final bool hasHeader = captionLines.length > 2;
+    // Caption has header / identifier
+    // See: https://www.w3.org/TR/webvtt1/#webvtt-cue-identifier for valid cue identifier
+    final bool hasHeader = !captionLines[0].contains(_webVTTArrow);
     if (hasHeader) {
       final int? tryParseCaptionNumber = int.tryParse(captionLines[0]);
       if (tryParseCaptionNumber != null) {

diff --git a/packages/video_player/video_player/pubspec.yaml b/packages/video_player/video_player/pubspec.yaml
@@ -3,7 +3,7 @@ description: Flutter plugin for displaying inline video with other Flutter
   widgets on Android, iOS, and web.
 repository: https://github.com/flutter/packages/tree/main/packages/video_player/video_player
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+video_player%22
-version: 2.9.2
+version: 2.9.3
 
 environment:
   sdk: ^3.4.0

diff --git a/packages/video_player/video_player/test/web_vtt_test.dart b/packages/video_player/video_player/test/web_vtt_test.dart
@@ -24,6 +24,21 @@ void main() {
       parsedFile = WebVTTCaptionFile(_valid_vtt_with_multiline);
       expect(parsedFile.captions.length, 1);
 
+      expect(parsedFile.captions[0].number, 2);
+      expect(parsedFile.captions[0].start,
+          const Duration(seconds: 2, milliseconds: 800));
+      expect(parsedFile.captions[0].end,
+          const Duration(seconds: 3, milliseconds: 283));
+      expect(parsedFile.captions[0].text,
+          '— It will perforate your stomach.\n— You could die.');
+    });
+
+    test('with Multiline without identifier', () {
+      parsedFile =
+          WebVTTCaptionFile(_valid_vtt_with_multiline_without_identifier);
+      expect(parsedFile.captions.length, 1);
+
+      expect(parsedFile.captions[0].number, 1);
       expect(parsedFile.captions[0].start,
           const Duration(seconds: 2, milliseconds: 800));
       expect(parsedFile.captions[0].end,
@@ -147,6 +162,15 @@ WEBVTT
 
 ''';
 
+const String _valid_vtt_with_multiline_without_identifier = '''
+WEBVTT
+
+00:02.800 --> 00:03.283
+— It will perforate your stomach.
+— You could die.
+
+''';
+
 /// See https://www.w3.org/TR/webvtt1/#styling
 const String _valid_vtt_with_styles = '''
 WEBVTT