frames from video

hi,

I am using imediadet to extract frames from video. My code looks like:


MediaDetClass md = new MediaDetClass();
md.Filename = videotextbox.Text;
md.CurrentStream = 0;

int startframe;
int endframe;
startframe = Convert.ToInt16(fromframe.Text);
endframe = Convert.ToInt16(toframe.Text);

for (int i = startframe; i <= endframe; i++)
{

string fBitmapName = i + "-sample" + ".bmp";
md.WriteBitmapBits(i, 640, 480, fBitmapName);
Image img = Image.FromFile(fBitmapName);
img.Save(@"c:\\frecproj\\frecdata\\temp_images\\" + i + "-sample" + ".jpg", ImageFormat.Jpeg);
img.Dispose();
System.IO.File.Delete(i + "-sample" + ".bmp");

}


The above code extratcs first few frames correclty but after 10 or 12 frames all the extracted frames look similar.

Help me on this.

Thanks
Paras.