/// <summary>Export a frame into a bitmap</summary>
/// <param name="position">Position of the frame</param>
public Bitmap GetBitmap(int position)
{
if (position > countFrames)
{
throw new Exception("Invalid frame position: " + position);
}
Avi.AVISTREAMINFO streamInfo = GetStreamInfo(StreamPointer);
Avi.BITMAPINFO bih = new Avi.BITMAPINFO();
int headerSize = Marshal.SizeOf(bih.bmiHeader);
//Decompress the frame and return a pointer to the DIB
int dib = Avi.AVIStreamGetFrame(getFrameObject, firstFrame + position);
//Copy the bitmap header into a managed struct
bih.bmiColors = this.palette;
bih.bmiHeader = (Avi.BITMAPINFOHEADER)Marshal.PtrToStructure(new IntPtr(dib), bih.bmiHeader.GetType());
if (bih.bmiHeader.biSizeImage < 1)
{
throw new Exception("Exception in VideoStreamGetFrame");
}
//copy the image
int framePaletteSize = bih.bmiHeader.biClrUsed * Avi.RGBQUAD_SIZE;
byte[] bitmapData = new byte[bih.bmiHeader.biSizeImage];
IntPtr dibPointer = new IntPtr(dib + Marshal.SizeOf(bih.bmiHeader) + framePaletteSize);
Marshal.Copy(dibPointer, bitmapData, 0, bih.bmiHeader.biSizeImage);
//copy bitmap info
byte[] bitmapInfo = new byte[Marshal.SizeOf(bih)];
IntPtr ptr = Marshal.AllocHGlobal(bitmapInfo.Length);
Marshal.StructureToPtr(bih, ptr, false);
Marshal.Copy(ptr, bitmapInfo, 0, bitmapInfo.Length);
Marshal.FreeHGlobal(ptr);
//create file header
Avi.BITMAPFILEHEADER bfh = new Avi.BITMAPFILEHEADER();
bfh.bfType = Avi.BMP_MAGIC_COOKIE;
bfh.bfSize = (Int32)(55 + bih.bmiHeader.biSizeImage); //size of file as written to disk
bfh.bfReserved1 = 0;
bfh.bfReserved2 = 0;
bfh.bfOffBits = Marshal.SizeOf(bih) + Marshal.SizeOf(bfh);
if (bih.bmiHeader.biBitCount < 8)
{
//There is a palette between header and pixel data
bfh.bfOffBits += bih.bmiHeader.biClrUsed * Avi.RGBQUAD_SIZE; //Avi.PALETTE_SIZE;
}
//write a bitmap stream
BinaryWriter bw = new BinaryWriter(new MemoryStream());
//write header
bw.Write(bfh.bfType);
bw.Write(bfh.bfSize);
bw.Write(bfh.bfReserved1);
bw.Write(bfh.bfReserved2);
bw.Write(bfh.bfOffBits);
//write bitmap info
bw.Write(bitmapInfo);
//write bitmap data
bw.Write(bitmapData);
Bitmap bmp = (Bitmap)Image.FromStream(bw.BaseStream);
Bitmap saveableBitmap = new Bitmap(bmp.Width, bmp.Height);
Graphics g = Graphics.FromImage(saveableBitmap);
g.DrawImage(bmp, 0, 0);
g.Dispose();
bmp.Dispose();
bw.Close();
return(saveableBitmap);
}