[chore] added some comments

example/midi_play.dart

@@ -13,6 +13,7 @@ import 'package:tekartik_midi/midi_player_base.dart';
 class _MidiPlayer extends MidiPlayerBase {
   @override
   void rawPlayEvent(PlayableEvent event) {
+    // ignore: avoid_print
     print(event);
   }
 

lib/midi_file_player.dart

@@ -7,10 +7,14 @@ import 'package:tekartik_common_utils/list_utils.dart';
 
 import 'midi.dart';
 
+/// Playable event
 class PlayableEvent {
+  /// in millis
   final num timestamp; // ms
+  /// The event to play
   final MidiEvent midiEvent;
 
+  /// Constructor
   PlayableEvent(this.timestamp, this.midiEvent);
 
   @override
@@ -21,10 +25,13 @@ class PlayableEvent {
 
 /// Prepare located events
 class LocatedTrackPlayer {
+  /// The track
   MidiTrack track;
 
+  /// Constructor
   LocatedTrackPlayer(this.track);
 
+  /// List of located events
   List<LocatedEvent> get preLocatedEvents {
     var events = <LocatedEvent>[];
     var currentTime = 0;

lib/midi_player_base.dart

@@ -417,10 +417,12 @@ abstract class MidiPlayerBase {
     }
   }
 
+  /// Get the total duration of the file
   num get totalDurationMs {
     return _midiFilePlayer!.totalDurationMs;
   }
 
+  /// Get the current position in the file
   num get currentAbsoluteMs {
     if (!_isPlaying) {
       return 0;

lib/src/buffer/midi_buffer.dart

@@ -1,4 +1,4 @@
-abstract class Buffer {
+abstract class _Buffer {
   late List<int> _data;
   int _position = 0;
 
@@ -19,7 +19,9 @@ abstract class Buffer {
   }
 }
 
-class InBuffer extends Buffer {
+/// Input buffer
+class InBuffer extends _Buffer {
+  /// Constructor
   InBuffer(List<int> data) {
     _data = data;
   }
@@ -29,37 +31,46 @@ class InBuffer extends Buffer {
 
   //int operator [](int index) => _data[index];
 
+  /// Get the next byte and advance the position
   int next() {
     return _data[_position++];
   }
 
+  /// Skip [count] bytes
   void skip(int count) {
     _position += count;
   }
 }
 
-class OutBuffer extends Buffer {
+/// Output buffer
+class OutBuffer extends _Buffer {
   @override
   int get length => _position;
 
+  /// Constructor
   OutBuffer(int size) {
     _data = List<int>.filled(size, 0);
   }
 
+  /// Restart the buffer
   void restart() {
     _position = 0;
   }
 
+  /// Add a byte
   void add(int value) {
     _data[_position++] = value;
   }
 
+  /// get the remaining count
   int get remainingAvailable => _data.length - _position;
 
+  /// Check if there is enough space
   bool hasAvailable(int size) {
     return remainingAvailable >= size;
   }
 
+  /// Check if the data is equal to the list
   bool equalsList(List<int> data) {
     if (length == data.length) {
       for (var i = 0; i < length; i++) {

lib/src/midi/event.dart

@@ -28,6 +28,7 @@ class TrackEvent {
   final int deltaTime;
   final MidiEvent midiEvent;
 
+  /// Constructor
   TrackEvent(this.deltaTime, this.midiEvent);
 
   @override
@@ -85,32 +86,40 @@ abstract class MidiEvent {
   /// Meta command.
   static const int cmdMetaEvent = 0xFF;
 
+  /// Constructor
   MidiEvent();
 
+  /// Constructor with command
   MidiEvent.withParam(this.command);
 
   /// Compute command from an event type and a channel
   static int commandChannel(int eventType, int channel) {
     return ((eventType << 4) | (channel & 0xF));
   }
 
+  /// Get the event type
   @Deprecated('use commandGetEventType')
   static int commandGetCommand(int command) => commandGetEventType(command);
 
+  /// Get the event type
   static int commandGetEventType(int command) {
     return ((command & 0xF0) >> 4);
   }
 
+  /// Get the channel
   static int commandGetChannel(int command) {
     // (command & 0xF)
     return (command & 0xF);
   }
 
+  /// Get the event type
   int get eventType => commandGetEventType(command);
 
+  /// Get the event type
   @Deprecated('user event type instead')
   int get codeCommand => eventType;
 
+  /// Base command
   factory MidiEvent.base(int command) {
     MidiEvent event;
 
@@ -174,19 +183,25 @@ abstract class MidiEvent {
 
 /// Channel event.
 abstract class ChannelEvent extends MidiEvent {
+  /// Channel
   int get channel => MidiEvent.commandGetChannel(command);
 
+  /// Constructor
   ChannelEvent();
 
-  ChannelEvent.withParam(int comand, int channel)
-      : super.withParam(MidiEvent.commandChannel(comand, channel));
+  /// Constructor with command and channel
+  ChannelEvent.withParam(int command, int channel)
+      : super.withParam(MidiEvent.commandChannel(command, channel));
 }
 
+/// Param1ByteEvent
 abstract class Param1ByteEvent extends ChannelEvent {
   int? _param1;
 
+  /// Constructor
   Param1ByteEvent();
 
+  /// Constructor with command, channel and param1
   Param1ByteEvent.withParam(super.command, super.channel, this._param1)
       : super.withParam();