got basic motion detection working

main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"crypto/sha256"
 	"encoding/base64"
+	"image"
 	"io/ioutil"
 	"log"
 	"net/http"
@@ -55,14 +56,39 @@ func stream(w http.ResponseWriter, r *http.Request) {
 	// TODO async for this?
 	saveStreamInstant(URL, img)
 
-	mat, err := gocv.IMDecode(img, gocv.IMReadColor)
-	newMat := gocv.NewMat()
+	h := sha256.New()
+	h.Write([]byte(URL))
+	streamDir := base64.URLEncoding.EncodeToString(h.Sum(nil))
+	streamStoreDir := filepath.Join(".", "streams", string(streamDir))
+	previousStreamInstantPath := filepath.Join(streamStoreDir, "previous.jpg")
 
-	gocv.ConvertScaleAbs(mat, &newMat, 2.0, 60)
+	_, err = os.Stat(previousStreamInstantPath)
+	previousExists := !os.IsNotExist(err)
 
-	gocvIMG, err := gocv.IMEncode(".jpg", newMat)
+	if previousExists {
+		newMat := gocv.NewMat()
 
-	w.Write(gocvIMG)
+		mat, err := gocv.IMDecode(img, gocv.IMReadColor)
+		if err != nil {
+			log.Fatal("Could not IMDecode img")
+		}
+
+		gocv.CvtColor(mat, &newMat, gocv.ColorBGRToGray)
+		gocv.GaussianBlur(newMat, &newMat, image.Point{X: 21, Y: 21}, 0, 0, gocv.BorderReflect)
+
+		previous := gocv.IMRead(previousStreamInstantPath, gocv.IMReadColor)
+
+		gocv.CvtColor(previous, &previous, gocv.ColorBGRToGray)
+		gocv.GaussianBlur(previous, &previous, image.Point{X: 21, Y: 21}, 0, 0, gocv.BorderReflect)
+
+		gocv.AbsDiff(previous, newMat, &newMat)
+
+		gocv.Threshold(newMat, &newMat, 25, 255, gocv.ThresholdBinary)
+
+		img, err = gocv.IMEncode(".jpg", newMat)
+	}
+
+	w.Write(img)
 }
 
 func saveStreamInstant(URL string, img []byte) {