/// <summary>Add a wave audio stream from another file to this file</summary>
 /// <param name="waveFileName">Name of the wave file to add</param>
 /// <param name="startAtFrameIndex">Index of the video frame at which the sound is going to start</param>
 public void AddAudioStream(String waveFileName, int startAtFrameIndex)
 {
     AviManager audioManager = new AviManager(waveFileName, true);
     AudioStream newStream = audioManager.GetWaveStream();
     AddAudioStream(newStream, startAtFrameIndex);
     audioManager.Close();
 }
        /// <summary>Copy a piece of video and wave sound int a new file</summary>
        /// <param name="newFileName">File name</param>
        /// <param name="startAtSecond">Start copying at second x</param>
        /// <param name="stopAtSecond">Stop copying at second y</param>
        /// <returns>AviManager for the new video</returns>
        public AviManager CopyTo(String newFileName, float startAtSecond, float stopAtSecond)
        {
            AviManager newFile = new AviManager(newFileName, false);

            try {
                //copy video stream

                VideoStream videoStream = GetVideoStream();

                int startFrameIndex = (int)(videoStream.FrameRate * startAtSecond);
                int stopFrameIndex = (int)(videoStream.FrameRate * stopAtSecond);

                videoStream.GetFrameOpen();
                Bitmap bmp = videoStream.GetBitmap(startFrameIndex);
                VideoStream newStream = newFile.AddVideoStream(false, videoStream.FrameRate, bmp);
                for (int n = startFrameIndex + 1; n <= stopFrameIndex; n++) {
                    bmp = videoStream.GetBitmap(n);
                    newStream.AddFrame(bmp);
                }
                videoStream.GetFrameClose();

                //copy audio stream

                AudioStream waveStream = GetWaveStream();

                Avi.AVISTREAMINFO streamInfo = new Avi.AVISTREAMINFO();
                Avi.PCMWAVEFORMAT streamFormat = new Avi.PCMWAVEFORMAT();
                int streamLength = 0;
                IntPtr ptrRawData = waveStream.GetStreamData(
                    ref streamInfo,
                    ref streamFormat,
                    ref streamLength);

                int startByteIndex = (int)( startAtSecond * (float)(waveStream.CountSamplesPerSecond * streamFormat.nChannels * waveStream.CountBitsPerSample) / 8);
                int stopByteIndex = (int)( stopAtSecond * (float)(waveStream.CountSamplesPerSecond * streamFormat.nChannels * waveStream.CountBitsPerSample) / 8);

                IntPtr ptrWavePart = new IntPtr(ptrRawData.ToInt32() + startByteIndex);

                byte[] rawData = new byte[stopByteIndex - startByteIndex];
                Marshal.Copy(ptrWavePart, rawData, 0, rawData.Length);
                Marshal.FreeHGlobal(ptrRawData);

                streamInfo.dwLength = rawData.Length;
                streamInfo.dwStart = 0;

                IntPtr unmanagedRawData = Marshal.AllocHGlobal(rawData.Length);
                Marshal.Copy(rawData, 0, unmanagedRawData, rawData.Length);
                newFile.AddAudioStream(unmanagedRawData, streamInfo, streamFormat, rawData.Length);
                Marshal.FreeHGlobal(unmanagedRawData);
            } catch (Exception ex) {
                newFile.Close();
                throw ex;
            }

            return newFile;
        }