Enabled previously commented out support for unsync lyrics/transcript…

…ion frames (USLT) - fixes #3.
tolo · Aug 3, 2022 · 578d1fa · 578d1fa
1 parent 2b07657
commit 578d1fa
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,8 +2,11 @@
 
 ##Version 0.2.0
 
+### Features
+* Enabled previously commented out support for unsync lyrics/transcription frames (USLT). Resolved with input from [pull request 3](https://github.com/tolo/id3tag/issues/3), added by @theckr96.
+
 ### Bug fixes
-* Fixed incorrect parsing of tag size field (resolves [issue 1](https://github.com/tolo/id3tag/issues/1), reported by @VirtualAstronaut). 
+* Fixed incorrect parsing of tag size field. Resolves [issue 1](https://github.com/tolo/id3tag/issues/1), reported by @VirtualAstronaut. 
 
 ##Version 0.1.0
 

diff --git a/lib/src/frames/frames.dart b/lib/src/frames/frames.dart
@@ -7,3 +7,4 @@ export 'picture_frame.dart';
 export 'text_information_frame.dart';
 //export 'url_frame.dart';
 export 'user_url_frame.dart';
+export 'lyrics_frame.dart';
diff --git a/lib/src/frames/transcription_frame.dart → lib/src/frames/lyrics_frame.dart b/lib/src/frames/transcription_frame.dart → lib/src/frames/lyrics_frame.dart
@@ -8,14 +8,14 @@ import 'frame_parser.dart';
 const String _frameName = 'USLT';
 
 
-class Transcription extends Frame {
+class Lyrics extends Frame {
   @override String get frameName => _frameName;
 
   final String language;
   final String contentDescriptor;
   final String lyrics;
 
-  Transcription({required this.language, required this.contentDescriptor, required this.lyrics});
+  Lyrics({required this.language, required this.contentDescriptor, required this.lyrics});
 
   @override
   Map<String, dynamic> toDictionary() {
@@ -29,25 +29,25 @@ class Transcription extends Frame {
 }
 
 
-class TranscriptionFrameParser extends FrameParser<Transcription> {
+class TranscriptionFrameParser extends FrameParser<Lyrics> {
   @override
   List<String> get frameNames => [_frameName];
 
   @override
-  Transcription? parseFrame(RawFrame rawFrame) {
+  Lyrics? parseFrame(RawFrame rawFrame) {
     final frameContent = rawFrame.frameContent;
     frameContent.readEncoding();
     final language = latin1.decode(frameContent.readBytes(3));
     var contentDescriptor = frameContent.readString(checkEncoding: false);
-    final lyrics = (frameContent.remainingBytes > 0)
-        ? frameContent.readString(checkEncoding: false, terminatorMandatory: false)
-        : contentDescriptor;
 
-    // TODO: Review
-    if (frameContent.remainingBytes == 0) {
+    var lyrics = '';
+    if (frameContent.remainingBytes > 0) {
+      lyrics = frameContent.readString(checkEncoding: false, terminatorMandatory: false);
+    } else {
+      lyrics = contentDescriptor;
       contentDescriptor = '';
     }
 
-    return Transcription(language: language, contentDescriptor: contentDescriptor, lyrics: lyrics);
+    return Lyrics(language: language, contentDescriptor: contentDescriptor, lyrics: lyrics);
   }
 }
diff --git a/lib/src/id3_parser.dart b/lib/src/id3_parser.dart
@@ -145,6 +145,7 @@ class ID3Parser implements ID3TagReader {
     addParser(TextInformationFrameParser());
     //addParser(UrlFrameParser()); // TODO
     addParser(UserUrlFrameParser());
+    addParser(TranscriptionFrameParser());
 
     return parserMap;
   }

diff --git a/lib/src/id3_tag.dart b/lib/src/id3_tag.dart
@@ -44,6 +44,9 @@ class ID3Tag {
     return _chapters;
   }
 
+  /// Gets the unsynchronized lyric/text transcription ('USLT') frame, represented as a [Lyrics] object.
+  List<Lyrics> get lyrics => framesWithTypeAndName<Lyrics>('USLT');
+
 
   ID3Tag({required this.tagVersion, required this.tagFound, required this.frames});
 

diff --git a/test/id3frames_test.dart b/test/id3frames_test.dart
@@ -35,4 +35,11 @@ void main() {
     final frame = tag.frames.firstWhereOrNull((f) => f.frameName == 'APIC');
     expect(frame, isNotNull);
   });
+
+  test('Tag should contain lyrics', () {
+    final parser = ID3Parser(File('test/apic.mp3')); // apic test file also contains uslt
+    final tag = parser.readTagSync();
+    final frame = tag.frames.firstWhereOrNull((f) => f.frameName == 'USLT');
+    expect(frame, isNotNull);
+  });
 }