diff --git a/filter/filters_circleci.go b/filter/filters_circleci.go
index e9b4b8df..bb49d712 100644
--- a/filter/filters_circleci.go
+++ b/filter/filters_circleci.go
@@ -37,7 +37,7 @@ func NewMOG(dst io.WriteCloser, area, threshold float64, history int, debug bool
 }
 
 // NewKNN returns a pointer to a new NoOp struct for testing purposes only.
-func NewKNN(dst io.WriteCloser, area, threshold float64, history, kernelSize int, debug bool, hf int) *NoOp {
+func NewKNN(dst io.WriteCloser, area, threshold float64, history, kernelSize int, debug bool, hf int, downscalingFactor int) *NoOp {
 	return &NoOp{dst: dst}
 }
 
diff --git a/filter/knn.go b/filter/knn.go
index b9b1c3f5..0009ce7d 100644
--- a/filter/knn.go
+++ b/filter/knn.go
@@ -49,17 +49,18 @@ type KNN struct {
 	hold    [][]byte                      // Will hold all frames up to hf (so only every hf frame is motion detected).
 	hf      int                           // The number of frames to be held.
 	hfCount int                           // Counter for the hold array.
+	scale   float64                       // The factor that frames will be downscaled by for motion detection.
 }
 
 // NewKNN returns a pointer to a new KNN filter struct.
-func NewKNN(dst io.WriteCloser, area, threshold float64, history, kernelSize int, debug bool, hf int) *KNN {
+func NewKNN(dst io.WriteCloser, area, threshold float64, history, kernelSize int, debug bool, hf int, downscalingFactor int) *KNN {
 	bs := gocv.NewBackgroundSubtractorKNNWithParams(history, threshold, false)
 	k := gocv.GetStructuringElement(gocv.MorphRect, image.Pt(kernelSize, kernelSize))
 	var windows []*gocv.Window
 	if debug {
 		windows = []*gocv.Window{gocv.NewWindow("KNN: Bounding boxes"), gocv.NewWindow("KNN: Motion")}
 	}
-	return &KNN{dst, area, &bs, k, debug, windows, make([][]byte, hf-1), hf, 0}
+	return &KNN{dst, area, &bs, k, debug, windows, make([][]byte, hf-1), hf, 0, 1 / float64(downscalingFactor)}
 }
 
 // Implements io.Closer.
@@ -94,6 +95,9 @@ func (m *KNN) Write(f []byte) (int, error) {
 	imgDelta := gocv.NewMat()
 	defer imgDelta.Close()
 
+	// Downsize image to speed up calculations.
+	gocv.Resize(img, &img, image.Point{}, m.scale, m.scale, gocv.InterpolationNearestNeighbor)
+
 	// Seperate foreground and background.
 	m.bs.Apply(img, &imgDelta)
 
diff --git a/revid/revid.go b/revid/revid.go
index c562799c..faac33a9 100644
--- a/revid/revid.go
+++ b/revid/revid.go
@@ -345,7 +345,7 @@ func (r *Revid) setupPipeline(mtsEnc func(dst io.WriteCloser, rate float64) (io.
 			case config.FilterVariableFPS:
 				r.filters[i] = filter.NewVariableFPS(dst, r.cfg.MinFPS, filter.NewMOG(dst, r.cfg.MOGMinArea, r.cfg.MOGThreshold, int(r.cfg.MOGHistory), r.cfg.ShowWindows, r.cfg.MotionInterval, r.cfg.MotionDownscaling))
 			case config.FilterKNN:
-				r.filters[i] = filter.NewKNN(dst, r.cfg.KNNMinArea, r.cfg.KNNThreshold, int(r.cfg.KNNHistory), int(r.cfg.KNNKernel), r.cfg.ShowWindows, r.cfg.MotionInterval)
+				r.filters[i] = filter.NewKNN(dst, r.cfg.KNNMinArea, r.cfg.KNNThreshold, int(r.cfg.KNNHistory), int(r.cfg.KNNKernel), r.cfg.ShowWindows, r.cfg.MotionInterval, r.cfg.MotionDownscaling)
 			case config.FilterDifference:
 				r.filters[i] = filter.NewDifference(dst, r.cfg.ShowWindows, r.cfg.DiffThreshold)
 			case config.FilterBasic: