How to render video from raw frames in WPF?

Question

I have a special video camera (using GigEVision protocol) that I control using a provided library. I can subscribe to a frame received event and then access the frame data via a IntPtr.

In my old WinForms app I could render the frame by either creating a Bitmap object from the data and setting it to a PictureBox Image, or by passing the PictureBox handle to a function in the provided library which would draw directly on the area.

What is the best and fastest way to do a similar thing in WPF? The video camera runs anywhere from 30 to 100 fps.

edit(1):

Since the frame received event is not on the UI thread it has to work across threads.

edit(2):

I found a solution using WriteableBitmap:

void camera_FrameReceived(IntPtr info, IntPtr frame) 
{
    if (VideoImageControlToUpdate == null)
    {
        throw new NullReferenceException("VideoImageControlToUpdate must be set before frames can be processed");
    }

    int width, height, size;
    unsafe
    {
        BITMAPINFOHEADER* b = (BITMAPINFOHEADER*)info;

        width = b->biWidth;
        height = b->biHeight;
        size = (int)b->biSizeImage;
    }
    if (height < 0) height = -height;

        //Warp space-time
        VideoImageControlToUpdate.Dispatcher.Invoke((Action)delegate {
        try
        {
            if (VideoImageControlToUpdateSource == null)
            {
                VideoImageControlToUpdateSource =
                    new WriteableBitmap(width, height, 96, 96, PixelFormats.Gray8, BitmapPalettes.Gray256);
            }
            else if (VideoImageControlToUpdateSource.PixelHeight != height ||
                     VideoImageControlToUpdateSource.PixelWidth != width)
            {
                VideoImageControlToUpdateSource =
                    new WriteableBitmap(width, height, 96, 96, PixelFormats.Gray8, BitmapPalettes.Gray256);
            }

            VideoImageControlToUpdateSource.Lock();

            VideoImageControlToUpdateSource.WritePixels(
                new Int32Rect(0, 0, width, height),
                frame,
                size,
                width);

            VideoImageControlToUpdateSource.AddDirtyRect(new System.Windows.Int32Rect(0, 0, width, height));
            VideoImageControlToUpdateSource.Unlock();
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.ToString());
        }
    });
}

In the above, VideoImageControlToUpdate is a WPF Image control.

For more speed I believe the VideoRendererElement found on codeplex is faster.

ima ima · Accepted Answer · 2009-08-14T08:16:54

Best way: WriteableBitmap.WritePixels(..., IntPtr source, ...)

Fastest way: Use WIC and all operations in IntPtr unmanaged memory. But why use WPF at all in this case? Consider using DirectX overlay if that kind of performance is required.

How to render video from raw frames in WPF?

1 Answers