HOW TO: Use the LEADTOOLS Video Callback Filter to recognize barcodes via webcam.

public void ReceiveProc(int pData, int lWidth, int lHeight, int lBitCount, int lSize, int bTopDown)

img = new RasterImage(
    RasterMemoryFlags.Conventional, //A combination of the RasterMemoryFlags enumeration members indicating the type of memory to allocate for the image data.
    lWidth, // Width of the image in pixels.
    lHeight, //Height of the image in pixels.
    lBitCount, //The number of bits per pixel.
    RasterByteOrder.Bgr, //Color order for 16-, 24-, 32-, 48- and 64-bit images.
    viewPerspective, //Specifies where the beginning of the image is stored.
    null, //The palette that the image will use. You can specify your own palette, or use null (Nothing in Visual Basic) for LEAD's fixed palette. The palette member is used only when bitsPerPixel is less than or equal to 8.
    null, //Unmanaged data pointer that will contain the image data when flags is RasterMemoryFlags.User.
    lSize); //Length in bytes of the data passed to userData. Only when used when userData is not IntPtr.Zero and flags is RasterMemoryFlags.User.
img.Access();
img.SetRow(0, new IntPtr(pData), lSize);
img.Release();
//at this point you have an image of the current frame in memory and you can apply processing, some form of recognition, etc.. 

BarcodeData[] DetectedBarcodecs = barcodeEngine.Reader.ReadBarcodes(image, LogicalRectangle.Empty, 0, new BarcodeSymbology[] { BarcodeSymbology.Unknown });
if (DetectedBarcodecs != null)
{
   foreach (BarcodeData data in DetectedBarcodecs)
   {
      if (data != null)
      {
         Console.WriteLine("Barcode Sybmology: " + data.Symbology);
      }
   }
}