public unsafe void ProcessFrame( UnmanagedImage videoFrame )
{
lock ( sync )
{
// check previous frame
if ( previousFrame == null )
{
// save image dimension
width = videoFrame.Width;
height = videoFrame.Height;
// alocate memory for previous and current frames
previousFrame = UnmanagedImage.Create( width, height, PixelFormat.Format8bppIndexed );
motionFrame = UnmanagedImage.Create( width, height, PixelFormat.Format8bppIndexed );
frameSize = motionFrame.Stride * height;
// temporary buffer
if ( suppressNoise )
{
tempFrame = UnmanagedImage.Create( width, height, PixelFormat.Format8bppIndexed );
}
// convert source frame to grayscale
Tools.ConvertToGrayscale( videoFrame, previousFrame );
return;
}
// check image dimension
if ( ( videoFrame.Width != width ) || ( videoFrame.Height != height ) )
return;
// convert current image to grayscale
Tools.ConvertToGrayscale( videoFrame, motionFrame );
// pointers to previous and current frames
byte* prevFrame = (byte*) previousFrame.ImageData.ToPointer( );
byte* currFrame = (byte*) motionFrame.ImageData.ToPointer( );
// difference value
int diff;
// 1 - get difference between frames
// 2 - threshold the difference
// 3 - copy current frame to previous frame
for ( int i = 0; i < frameSize; i++, prevFrame++, currFrame++ )
{
// difference
diff = (int) *currFrame - (int) *prevFrame;
// copy current frame to previous
*prevFrame = *currFrame;
// treshold
*currFrame = ( ( diff >= differenceThreshold ) || ( diff <= differenceThresholdNeg ) ) ? (byte) 255 : (byte) 0;
}
if ( suppressNoise )
{
// suppress noise and calculate motion amount
AForge.SystemTools.CopyUnmanagedMemory( tempFrame.ImageData, motionFrame.ImageData, frameSize );
erosionFilter.Apply( tempFrame, motionFrame );
}
// calculate amount of motion pixels
pixelsChanged = 0;
byte* motion = (byte*) motionFrame.ImageData.ToPointer( );
for ( int i = 0; i < frameSize; i++, motion++ )
{
pixelsChanged += ( *motion & 1 );
}
}
}