tidying up and adding any other comments

filter/basic.go

@@ -96,18 +96,14 @@ func (b *BasicFilter) Close() error {
 func (b *BasicFilter) Process(j int, wg *sync.WaitGroup) {
 	defer wg.Done()
 	for i := 0; i < b.w; i++ {
-		// ti0 := time.Now()
 		n := b.img.At(i, j)
-		// ti1 := time.Now()
 		R, G, B, _ := n.RGBA()
-		// ti2 := time.Now()
 
+		// Compare the difference of the RGB values of each pixel to the background image.
 		diffB := absDiff(B, b.bg[j][i][2])
 		diffR := absDiff(R, b.bg[j][i][0])
 		diffG := absDiff(G, b.bg[j][i][1])
 
-		// ti3 := time.Now()
-
 		diff := diffR + diffG + diffB
 
 		if diff > 45000 {
@@ -121,17 +117,9 @@ func (b *BasicFilter) Process(j int, wg *sync.WaitGroup) {
 				b.bwImg.SetRGBA(i, j, color.RGBA{0x00, 0x00, 0x00, 0xff})
 			}
 		}
-		// ti4 := time.Now()
+
 		// Update backgound image.
 		copy(b.bg[j][i][:], []uint32{R, G, B})
-		// ti5 := time.Now()
-
-		// fmt.Print("At: ", ti1.Sub(ti0).Nanoseconds(), "\n")
-		// fmt.Print("RGBA: ", ti2.Sub(ti1).Nanoseconds(), "\n")
-		// fmt.Print("3x absDiff: ", ti3.Sub(ti2).Nanoseconds(), "\n")
-		// fmt.Print("total diff + threshold + debug: ", ti4.Sub(ti3).Nanoseconds(), "\n")
-		// fmt.Print("update bg: ", ti5.Sub(ti4).Nanoseconds(), "\n")
-		// fmt.Print("Total: ", time.Now().Sub(ti0).Nanoseconds(), "\n\n")
 	}
 }
 
@@ -140,7 +128,7 @@ func (b *BasicFilter) Process(j int, wg *sync.WaitGroup) {
 // are written to the destination encoder, frames without are discarded.
 func (b *BasicFilter) Write(f []byte) (int, error) {
 	t0 := time.Now()
-	//decode MJPEG
+	// Decode MJPEG.
 	r := bytes.NewReader(f)
 	var err error
 	b.img, err = jpeg.Decode(r)
@@ -150,8 +138,8 @@ func (b *BasicFilter) Write(f []byte) (int, error) {
 
 	t1 := time.Now()
 
-	//get background image and save a new background image if needed
-	//first frame must always be sent
+	// Get background image and save a new background image if needed
+	// first frame must always be sent.
 	if b.bg == nil {
 		bounds := b.img.Bounds()
 		b.w = bounds.Max.X
@@ -174,13 +162,9 @@ func (b *BasicFilter) Write(f []byte) (int, error) {
 		return len(f), nil
 	}
 
-	//for all pixels get the difference from the background image
-
-	// c := make(chan int)
-	// fmt.Print("channel made \n")
-	var m sync.Mutex
-
+	// Use 4x goroutines to each process one row of pixels
 	j := 0
+	var m sync.Mutex
 	m.Lock()
 	var wg sync.WaitGroup
 
@@ -198,9 +182,7 @@ func (b *BasicFilter) Write(f []byte) (int, error) {
 		m.Unlock()
 	}
 
-	t2 := time.Now()
-
-	//visualise
+	// Will save a video of where motion is detected in motion.mjpeg (in the current folder).
 	if b.debug {
 		col := color.RGBA{200, 100, 0, 255}
 		d := &font.Drawer{
@@ -221,19 +203,12 @@ func (b *BasicFilter) Write(f []byte) (int, error) {
 			return len(f), err
 		}
 	}
-	t3 := time.Now()
 
-	fmt.Print("Encode: ", t1.Sub(t0).Milliseconds(), "\n")
-	fmt.Print("Calc loop: ", t2.Sub(t1).Milliseconds(), "\n")
-	fmt.Print("VLC: ", t3.Sub(t2).Milliseconds(), "\n")
-	fmt.Print("Total: ", time.Now().Sub(t0).Milliseconds(), "\n\n")
-
-	//choose a threshold that motion is detected for if greater
+	// If there are not enough motion pixels then discard the frame.
 	if b.motion < 1000 {
 		return len(f), nil
 	}
-	//discard non motion frames
 
-	//write motion frames
+	// Write all motion frames.
 	return b.dst.Write(f)
 }