diff --git a/Vocaluxe/Lib/Video/IVideoDecoder.cs b/Vocaluxe/Lib/Video/IVideoDecoder.cs
index 6c48a24e..cf17f822 100644
--- a/Vocaluxe/Lib/Video/IVideoDecoder.cs
+++ b/Vocaluxe/Lib/Video/IVideoDecoder.cs
@@ -23,31 +23,94 @@ namespace Vocaluxe.Lib.Video
 {
     interface IVideoDecoder
     {
+        /// <summary>
+        /// Initializes videodecoder. Got to be called before usage
+        /// </summary>
+        /// <returns>True on success, false if something went wrong.</returns>
         bool Init();
+
+        /// <summary>
+        /// Close all video streams
+        /// </summary>
         void CloseAll();
 
+        /// <summary>
+        /// Loads the file with the given file path.
+        /// </summary>
+        /// <param name="videoFileName">Absolute file path of the video file</param>
+        /// <returns>StreamID &gt;=0 on success or -1 on failure</returns>
         int Load(string videoFileName);
+
+        /// <summary>
+        /// Closes the stream with the given ID
+        /// </summary>
+        /// <param name="streamID">ID of the stream</param>
+        /// <returns>true if stream was closed, false if stream doesn't exist or already closed</returns>
         bool Close(int streamID);
+
+        /// <summary>
+        /// Gets the number of streams currently active
+        /// </summary>
+        /// <returns></returns>
         int GetNumStreams();
 
+        /// <summary>
+        /// Gets the length of the video in s
+        /// </summary>
+        /// <param name="streamID">Id of the stream</param>
+        /// <returns>Length of the video in s</returns>
         float GetLength(int streamID);
 
         /// <summary>
+        /// Gets a frame of the video and sets the current video time
         /// </summary>
-        /// <param name="streamID"></param>
-        /// <param name="frame"></param>
-        /// <param name="time"></param>
-        /// <param name="videoTime"></param>
-        /// <returns>True if frame is valid</returns>
+        /// <param name="streamID">Id of the stream</param>
+        /// <param name="frame">Reference to already initialized video texture (from previous calls). If null, one will be created.<br/>
+        /// Returns the current video frame which might be outdated if time != current (internal) video position or unchanged (even null) if none is available.</param>
+        /// <param name="time">The position in s of the video you want to get a frame of. If != current (internal) video position, it will seek to get to right position.<br/>
+        /// <b>Note:</b>Will be ignored for looped playback!</param>
+        /// <param name="videoTime">The actual position in s of the returned frame. Should be ~ time+VideoGap</param>
+        /// <returns>True if frame is valid, false: frame and videoTime might be unchanged or invalid</returns>
         bool GetFrame(int streamID, ref CTexture frame, float time, out float videoTime);
 
+        /// <summary>
+        /// Seeks to given position
+        /// </summary>
+        /// <param name="streamID">Id of the stream</param>
+        /// <param name="start">Position to seek to</param>
+        /// <param name="gap">New video gap -> Actual position will be start+gap</param>
+        /// <returns>True on success</returns>
         bool Skip(int streamID, float start, float gap);
+
+        /// <summary>
+        /// Set if the video should be looped
+        /// </summary>
+        /// <param name="streamID">Id of the stream</param>
+        /// <param name="loop">True if it should be looped</param>
         void SetLoop(int streamID, bool loop);
+
+        /// <summary>
+        /// Pauses the video (no new frames will be decoded)
+        /// </summary>
+        /// <param name="streamID">Id of the stream</param>
         void Pause(int streamID);
+
+        /// <summary>
+        /// Resumes a paused video
+        /// </summary>
+        /// <param name="streamID">Id of the stream</param>
         void Resume(int streamID);
 
+        /// <summary>
+        /// Check if the given video is finished
+        /// </summary>
+        /// <param name="streamID">Id of the stream</param>
+        /// <returns>True if all frames are shown</returns>
         bool Finished(int streamID);
 
+        /// <summary>
+        /// Do a step of the decoder in unthreaded decoders. Should be called once every frame.
+        /// </summary>
         void Update();
     }
 }
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