AnimatGuiCtrls.Video.AviManager.CopyTo C# (CSharp) Method

        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;
        }