Workaround for MediaPlayer thumbnail app causes infinite loop

[William Johnston]

Hi,

A support technician proposed a workaround to black images created for thumbnails.

The code to create a thumbnail is below:

//passes results to Response.Output Stream
private void CreateThumbnail (string url)
{
try
{
MediaPlayer mp = new MediaPlayer();
mp.Open(new Uri(url));
mp.Position = new TimeSpan(00, 00, 01);
Workaround(mp);

RenderTargetBit map rtb = new RenderTargetBit map(260, 184, 1 / 200, 1 / 200, PixelFormats.Pb gra32);

DrawingVisual dv = new DrawingVisual() ;
DrawingContext dc = dv.RenderOpen() ;
RectAnimation ra = new RectAnimation() ;
dc.DrawVideo(mp , new Rect(0, 0, 260, 184));

dc.Close();
rtb.Render(dv);

BmpBitmapEncode r encoder = new BmpBitmapEncode r();
encoder.Frames. Add(BitmapFrame .Create(rtb));

MemoryStream memoryStream = new MemoryStream();
encoder.Save(me moryStream);

Bitmap bmp = new Bitmap(memorySt ream);
Response.Conten tType = "image/JPEG";
bmp.Save(Respon se.OutputStream , ImageFormat.Jpe g);
}
catch (Exception e)
{
System.Console. WriteLine("Crea teThumbnail: " + e.Message);
System.Environm ent.Exit(1);
}
}

private void Workaround(Medi aPlayer mp)
{
mp.Play();
TimeSpan startPosition = mp.Position;
while (startPosition == mp.Position)
{
System.Threadin g.Thread.Sleep( 1000);
}
mp.Pause();
}

private const string defaultVideoURL = "http://tenbase2.com/movie_clips/Glenn%20Beck%20 11_07_07/VTS_01_1/movie_segment5. mp2";
An infinite loop sometimes occurs for the Workaround while loop. A black thumbnail is created without the while loop.

Any suggestions on how to reliably create a thumbnail?

This app is an HTTP Handler as an ASP.NET Web application.

Thanks,
William Johnston