feat: Add metadata writers

README.md

@@ -12,6 +12,8 @@ It's still in development and there's some metadat format that I could implement
 
 ## Usage
 
+### Read
+
 ```dart
 import 'dart:io';
 
@@ -28,6 +30,32 @@ void main() {
 }
 ```
 
+### Write
+
+This use case is a bit more complicated. You have to manipulate the raw metadata and update the good field.
+
+```dart
+void main() {
+  final fullMetadata = readAllMetadata(track);
+
+  switch (fullMetadata) {
+    case Mp3Metadata m:
+      m.songName = "New title";
+      break;
+    case Mp4Metadata m:
+      m.title = "New title";
+      break;
+    case VorbisMetadata m:
+      m.title = ["New title"];
+      break;
+  }
+
+  writeMetadata(track, fullMetadata);
+}
+```
+
+Also, all the ID3v2 metadata will be written in the minor version 4.
+
 ## Performance
 
 By running the following code on my laptop with a SSD, it ables to get the metadata of 3392 tracks in less than 200ms (if we don't fetch the covers). With the covers, about 400ms.

example/main.dart

@@ -1,15 +1,35 @@
 import 'dart:io';
 
 import 'package:audio_metadata_reader/audio_metadata_reader.dart';
+import 'package:audio_metadata_reader/src/metadata/base.dart';
+import 'package:audio_metadata_reader/src/writer.dart';
 
-Future<void> main() async {
+void main() {
   final track = File("Pieces.mp3");
 
   // Getting the image of a track can be heavy and slow the reading
-  final metadata = await readMetadata(track, getImage: false);
+  final metadata = readMetadata(track, getImage: false);
 
   print(metadata.title);
   print(metadata.album);
   print(metadata.duration);
   // etc...
+
+  print("Now we are going to rewrite the metadata");
+
+  final fullMetadata = readAllMetadata(track);
+
+  switch (fullMetadata) {
+    case Mp3Metadata m:
+      m.songName = "New title";
+      break;
+    case Mp4Metadata m:
+      m.title = "New title";
+      break;
+    case VorbisMetadata m:
+      m.title = ["New title"];
+      break;
+  }
+
+  writeMetadata(track, fullMetadata);
 }

lib/audio_metadata_reader.dart

@@ -2,6 +2,26 @@ library audio_metadata_reader;
 
 export "src/parsers/tag_parser.dart" show AudioMetadata, Picture;
 export 'src/metadata/base.dart' show PictureType;
+export 'src/utils/metadata_parser_exception.dart' show MetadataParserException;
+export 'src/parser.dart' show readMetadata, readAllMetadata;
+
+export 'src/parsers/id3v1.dart' show ID3v1Parser;
+export 'src/parsers/id3v2.dart' show ID3v2Parser;
+export 'src/parsers/flac.dart' show FlacParser;
+export 'src/parsers/mp4.dart' show MP4Parser;
+export 'src/parsers/ogg.dart' show OGGParser;
+
+export 'src/writers/id3v4_writer.dart' show Id3v4Writer;
 export 'src/utils/metadata_parser_exception.dart'
     show MetadataParserException, NoMetadataParserException;
 export 'src/parser.dart' show readMetadata;
+export 'src/utils/metadata_parser_exception.dart' show MetadataParserException;
+export 'src/parser.dart' show readMetadata, readAllMetadata;
+
+export 'src/parsers/id3v1.dart' show ID3v1Parser;
+export 'src/parsers/id3v2.dart' show ID3v2Parser;
+export 'src/parsers/flac.dart' show FlacParser;
+export 'src/parsers/mp4.dart' show MP4Parser;
+export 'src/parsers/ogg.dart' show OGGParser;
+
+export 'src/writers/id3v4_writer.dart' show Id3v4Writer;

lib/src/metadata/base.dart

@@ -1,3 +1,14 @@
+import 'dart:collection';
+import 'dart:typed_data';
+
+import 'package:audio_metadata_reader/audio_metadata_reader.dart';
+
+part 'mp3_metadata.dart';
+part 'mp4_metadata.dart';
+part 'vorbis_metadata.dart';
+
+sealed class ParserTag {}
+
 enum PictureType {
   other,
   fileIcon32x32,

lib/src/metadata/mp3_metadata.dart

@@ -1,8 +1,6 @@
 // https://teslabs.com/openplayer/docs/docs/specs/id3v2.3.0%20-%20ID3.org.pdf
 
-import 'dart:typed_data';
-
-import '../parsers/tag_parser.dart';
+part of 'base.dart';
 
 class Mp3Metadata extends ParserTag {
   String? album; // TALB

lib/src/metadata/mp4_metadata.dart

@@ -1,4 +1,4 @@
-import 'package:audio_metadata_reader/src/parsers/tag_parser.dart';
+part of 'base.dart';
 
 class Mp4Metadata extends ParserTag {
   String? title;

lib/src/metadata/vorbis_metadata.dart

@@ -1,6 +1,4 @@
-import 'dart:collection';
-
-import 'package:audio_metadata_reader/src/parsers/tag_parser.dart';
+part of 'base.dart';
 
 // https://xiph.org/vorbis/doc/v-comment.html
 // https://exiftool.org/TagNames/Vorbis.html

lib/src/parser.dart

@@ -1,21 +1,14 @@
 import 'dart:io';
 
 import 'package:audio_metadata_reader/audio_metadata_reader.dart';
-import 'package:audio_metadata_reader/src/metadata/mp3_metadata.dart';
-import 'package:audio_metadata_reader/src/metadata/mp4_metadata.dart';
-import 'package:audio_metadata_reader/src/metadata/vorbis_metadata.dart';
-import 'package:audio_metadata_reader/src/parsers/id3v1.dart';
-import 'package:audio_metadata_reader/src/parsers/id3v2.dart';
-import 'package:audio_metadata_reader/src/parsers/mp4.dart';
-import 'package:audio_metadata_reader/src/parsers/ogg.dart';
-import 'package:audio_metadata_reader/src/parsers/flac.dart';
+import 'package:audio_metadata_reader/src/metadata/base.dart';
 
 /// Parse the metadata of a file.
 ///
 /// It automatically detects the type of the file (`.mp3`, `.ogg`, `.flac` etc)
 /// and select the matching file parser.
 ///
-/// If there's no parser or an error, a `InvalidTag` instance should be returned.
+/// If there's no parser or an error, a `MetadataParserException` exception is raised.
 ///
 /// By default, it does not fetch the images of the file. Because some
 /// images/covers are sometimes huge (~5MB), it can drastically make the
@@ -179,3 +172,41 @@ AudioMetadata readMetadata(File track, {bool getImage = false}) {
     track: track,
   );
 }
+
+/// Parse the metadata of a file and return ALL the metadata. It contains more information
+/// than `readMetadata(...)` but you need more knowledges about the metadata specifications.
+///
+/// Use this one if you want to rewrite the metadata later.
+///
+/// It automatically detects the type of the file (`.mp3`, `.ogg`, `.flac` etc)
+/// and select the matching file parser.
+///
+/// If there's no parser or an error, a `MetadataParserException` exception is raised.
+///
+/// By default, it fetches the cover images
+ParserTag readAllMetadata(File track, {bool getImage = true}) {
+  final reader = track.openSync();
+
+  try {
+    if (ID3v2Parser.canUserParser(reader)) {
+      return ID3v2Parser(fetchImage: getImage).parse(reader);
+    } else if (FlacParser.canUserParser(reader)) {
+      return FlacParser(fetchImage: getImage).parse(reader);
+    } else if (MP4Parser.canUserParser(reader)) {
+      return MP4Parser(fetchImage: getImage).parse(reader);
+    } else if (OGGParser.canUserParser(reader)) {
+      return OGGParser(fetchImage: getImage).parse(reader);
+    } else if (ID3v2Parser.isID3v1(reader)) {
+      return ID3v1Parser().parse(reader);
+    }
+  } catch (e, trace) {
+    print(trace);
+    throw MetadataParserException(track: track, message: e.toString());
+  }
+
+  throw MetadataParserException(
+    track: track,
+    message:
+        "No available parser for this file. Please raise an issue in Github",
+  );
+}

lib/src/parsers/flac.dart

@@ -3,7 +3,6 @@ import 'dart:io';
 import 'dart:typed_data';
 
 import 'package:audio_metadata_reader/src/metadata/base.dart';
-import 'package:audio_metadata_reader/src/metadata/vorbis_metadata.dart';
 import 'package:audio_metadata_reader/src/parsers/tag_parser.dart';
 import 'package:audio_metadata_reader/src/utils/buffer.dart';
 

lib/src/parsers/id3v1.dart

@@ -2,7 +2,7 @@ import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
 
-import 'package:audio_metadata_reader/src/metadata/mp3_metadata.dart';
+import 'package:audio_metadata_reader/src/metadata/base.dart';
 import 'package:audio_metadata_reader/src/parsers/tag_parser.dart';
 import 'package:audio_metadata_reader/src/utils/bit_manipulator.dart';
 import 'package:audio_metadata_reader/src/utils/buffer.dart';

lib/src/parsers/id3v2.dart

@@ -3,7 +3,6 @@ import 'dart:io';
 import 'dart:typed_data';
 import 'package:audio_metadata_reader/src/constants/id3_genres.dart';
 import 'package:audio_metadata_reader/src/metadata/base.dart';
-import 'package:audio_metadata_reader/src/metadata/mp3_metadata.dart';
 import 'package:audio_metadata_reader/src/utils/bit_manipulator.dart';
 import 'package:audio_metadata_reader/src/utils/buffer.dart';
 import 'package:charset/charset.dart';

lib/src/parsers/mp4.dart

@@ -2,7 +2,7 @@ import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
 
-import 'package:audio_metadata_reader/src/metadata/mp4_metadata.dart';
+import 'package:audio_metadata_reader/src/metadata/base.dart';
 import 'package:audio_metadata_reader/src/parsers/tag_parser.dart';
 import 'package:mime/mime.dart';
 

lib/src/parsers/ogg.dart

@@ -1,7 +1,7 @@
 import 'dart:io';
 import 'dart:typed_data';
 
-import 'package:audio_metadata_reader/src/metadata/vorbis_metadata.dart';
+import 'package:audio_metadata_reader/src/metadata/base.dart';
 import 'package:audio_metadata_reader/src/parsers/tag_parser.dart';
 import 'package:audio_metadata_reader/src/parsers/vorbis_comment.dart';
 import 'package:audio_metadata_reader/src/utils/bit_manipulator.dart';

lib/src/parsers/tag_parser.dart

@@ -27,9 +27,6 @@ class Picture {
   }
 }
 
-/// An abstract class to represent the result of a parser
-abstract class ParserTag {}
-
 /// A generic class to gather the metadata. To make it universal, some format-specific metadata
 /// are dropped.
 ///

lib/src/parsers/vorbis_comment.dart

@@ -2,7 +2,6 @@ import 'dart:convert';
 import 'dart:typed_data';
 
 import 'package:audio_metadata_reader/src/metadata/base.dart';
-import 'package:audio_metadata_reader/src/metadata/vorbis_metadata.dart';
 import 'package:audio_metadata_reader/src/parsers/tag_parser.dart';
 
 void parseVorbisComment(

lib/src/utils/pad_bit.dart

@@ -0,0 +1,29 @@
+extension A on List<int> {
+  List<int> padBitLeft(int desiredLength, int paddingBit) {
+    if (length >= desiredLength) {
+      return this; // No padding needed
+    }
+
+    if (paddingBit != 0 && paddingBit != 1) {
+      throw ArgumentError("Padding bit must be 0 or 1.");
+    }
+
+    int paddingCount = desiredLength - length;
+    List<int> padding = List.filled(paddingCount, paddingBit);
+    return [...padding, ...this];
+  }
+
+  List<int> padBitRight(int desiredLength, int paddingBit) {
+    if (length >= desiredLength) {
+      return this; // No padding needed
+    }
+
+    if (paddingBit != 0 && paddingBit != 1) {
+      throw ArgumentError("Padding bit must be 0 or 1.");
+    }
+
+    int paddingCount = desiredLength - length;
+    List<int> padding = List.filled(paddingCount, paddingBit);
+    return [...this, ...padding];
+  }
+}

lib/src/writer.dart

@@ -0,0 +1,12 @@
+import 'dart:io';
+
+import 'package:audio_metadata_reader/audio_metadata_reader.dart';
+import 'package:audio_metadata_reader/src/metadata/base.dart';
+
+void writeMetadata(File track, ParserTag metadata) {
+  final reader = track.openSync();
+
+  if (ID3v2Parser.canUserParser(reader)) {
+    Id3v4Writer().write(track, metadata as Mp3Metadata);
+  }
+}