diff --git a/lib/src/enums.dart b/lib/src/enums.dart
index 9024bc6..6ffcd3b 100644
--- a/lib/src/enums.dart
+++ b/lib/src/enums.dart
@@ -3,6 +3,14 @@ enum RecorderAudioChannel { INPUT, OUTPUT }
 /// RTCDataChannelMessage type
 enum MessageType { text, binary }
 
+enum DataChannelProtocol { sctp , quic }
+
+enum SdpType { offer, answer }
+
+enum TrackType { audio, video }
+
+enum DeviceInfoType { videoInput, audioInput, audioOutput }
+
 enum RTCDataChannelState {
   RTCDataChannelConnecting,
   RTCDataChannelOpen,
@@ -204,3 +212,70 @@ RTCDegradationPreference degradationPreferenceforString(String? degradation) {
   }
   return RTCDegradationPreference.BALANCED;
 }
+
+SdpType? sdpTypeForString(String? type) {
+  switch (type) {
+    case 'offer':
+      return SdpType.offer;
+    case 'answer':
+      return SdpType.answer;
+    default:
+      return null;
+  }
+}
+
+final typeSdpTypeToString = <SdpType, String>{
+  SdpType.offer: 'offer',
+  SdpType.answer: 'answer',
+};
+
+TrackType? trackTypeForString(String? type) {
+  switch (type) {
+    case 'audio':
+      return TrackType.audio;
+    case 'video':
+      return TrackType.video;
+    default:
+      return null;
+  }
+}
+
+final typeTrackTypeToString = <TrackType, String>{
+  TrackType.audio: 'audio',
+  TrackType.video: 'video',
+};
+
+DeviceInfoType? deviceInfoTypeForString(String? type) {
+  switch (type) {
+    case 'audioinput':
+      return DeviceInfoType.audioInput;
+    case 'audiooutput':
+      return DeviceInfoType.audioOutput;
+    case 'videoinput':
+      return DeviceInfoType.videoInput;
+    default:
+      return null;
+  }
+}
+
+final typeDeviceInfoTypeToString = <DeviceInfoType, String>{
+  DeviceInfoType.audioInput: 'audioinput',
+  DeviceInfoType.audioOutput: 'audiooutput',
+  DeviceInfoType.videoInput: 'videoinput',
+};
+
+DataChannelProtocol? dataChannelProtocolForString(String? type) {
+  switch (type) {
+    case 'quic':
+      return DataChannelProtocol.quic;
+    case 'sctp':
+      return DataChannelProtocol.sctp;
+    default:
+      return null;
+  }
+}
+
+final typeDataChannelProtocolToString = <DataChannelProtocol, String>{
+  DataChannelProtocol.quic: 'quic',
+  DataChannelProtocol.sctp: 'sctp',
+};
\ No newline at end of file
diff --git a/lib/src/media_stream_track.dart b/lib/src/media_stream_track.dart
index c7f9b8f..b3477b5 100644
--- a/lib/src/media_stream_track.dart
+++ b/lib/src/media_stream_track.dart
@@ -1,5 +1,7 @@
 import 'dart:typed_data';
 
+import 'package:webrtc_interface/src/enums.dart';
+
 typedef StreamTrackCallback = Function();
 
 abstract class MediaStreamTrack {
@@ -15,9 +17,9 @@ abstract class MediaStreamTrack {
   /// If the corresponding source has or had no label, returns an empty string.
   String? get label;
 
-  /// Returns the string 'audio' if this object represents an audio track
+  /// Returns the type 'audio' if this object represents an audio track
   /// or 'video' if this object represents a video track.
-  String? get kind;
+  TrackType? get kind;
 
   /// Callback for onmute event
   StreamTrackCallback? onMute;
diff --git a/lib/src/mediadevices.dart b/lib/src/mediadevices.dart
index 9e43527..2b78553 100644
--- a/lib/src/mediadevices.dart
+++ b/lib/src/mediadevices.dart
@@ -1,3 +1,5 @@
+import 'package:webrtc_interface/src/enums.dart';
+
 import 'media_stream.dart';
 
 class MediaStreamConstraints {
@@ -150,7 +152,7 @@ class MediaDeviceInfo {
 
   /// Returns an enumerated value that is either 'videoinput', 'audioinput' or
   /// 'audiooutput'.
-  final String? kind;
+  final DeviceInfoType? kind;
 
   /// Returns a String that is a label describing this device
   /// (for example "External USB Webcam").
diff --git a/lib/src/rtc_data_channel.dart b/lib/src/rtc_data_channel.dart
index de5692f..70e746a 100644
--- a/lib/src/rtc_data_channel.dart
+++ b/lib/src/rtc_data_channel.dart
@@ -7,8 +7,8 @@ class RTCDataChannelInit {
   bool ordered = true;
   int maxRetransmitTime = -1;
   int maxRetransmits = -1;
-  String protocol = 'sctp'; //sctp | quic
-  String binaryType = 'text'; // "binary" || text
+  DataChannelProtocol protocol = DataChannelProtocol.sctp;
+  MessageType binaryType = MessageType.text;
   bool negotiated = false;
   int id = 0;
   Map<String, dynamic> toMap() {
@@ -18,7 +18,7 @@ class RTCDataChannelInit {
         //https://www.chromestatus.com/features/5198350873788416
         'maxPacketLifeTime': maxRetransmitTime,
       if (maxRetransmits > 0) 'maxRetransmits': maxRetransmits,
-      'protocol': protocol,
+      'protocol': typeDataChannelProtocolToString[protocol],
       'negotiated': negotiated,
       'id': id
     };
diff --git a/lib/src/rtc_session_description.dart b/lib/src/rtc_session_description.dart
index 07b390d..3edb8e5 100644
--- a/lib/src/rtc_session_description.dart
+++ b/lib/src/rtc_session_description.dart
@@ -1,8 +1,10 @@
+import 'enums.dart';
+
 class RTCSessionDescription {
   RTCSessionDescription(this.sdp, this.type);
   String? sdp;
-  String? type;
+  SdpType? type;
   dynamic toMap() {
-    return {'sdp': sdp, 'type': type};
+    return {'sdp': sdp, 'type': typeSdpTypeToString[type]};
   }
 }