add example opencv

examples/opencv.go

@@ -0,0 +1,101 @@
+package examples
+
+import (
+	"fmt"
+	"image"
+	"image/color"
+	"io"
+	"log"
+
+	ffmpeg "github.com/u2takey/ffmpeg-go"
+	"gocv.io/x/gocv"
+)
+
+func readProcess(infileName string, writer io.WriteCloser) <-chan error {
+	log.Println("Starting ffmpeg process1")
+	done := make(chan error)
+	go func() {
+		err := ffmpeg.Input(infileName).
+			Output("pipe:",
+				ffmpeg.KwArgs{
+					"format": "rawvideo", "pix_fmt": "rgb24",
+				}).
+			WithOutput(writer).
+			Run()
+		log.Println("ffmpeg process1 done")
+		_ = writer.Close()
+		done <- err
+		close(done)
+	}()
+	return done
+}
+
+func openCvProcess(xmlFile string, reader io.ReadCloser, w, h int) {
+	// open display window
+	window := gocv.NewWindow("Face Detect")
+	defer window.Close()
+
+	// color for the rect when faces detected
+	blue := color.RGBA{0, 0, 255, 0}
+
+	classifier := gocv.NewCascadeClassifier()
+	defer classifier.Close()
+
+	if !classifier.Load(xmlFile) {
+		fmt.Printf("Error reading cascade file: %v\n", xmlFile)
+		return
+	}
+
+	frameSize := w * h * 3
+	buf := make([]byte, frameSize, frameSize)
+	for {
+		n, err := io.ReadFull(reader, buf)
+		if n == 0 || err == io.EOF {
+			return
+		} else if n != frameSize || err != nil {
+			panic(fmt.Sprintf("read error: %d, %s", n, err))
+		}
+		img, err := gocv.NewMatFromBytes(h, w, gocv.MatTypeCV8UC3, buf)
+		if err != nil {
+			fmt.Println("decode fail", err)
+		}
+		if img.Empty() {
+			continue
+		}
+
+		// detect faces
+		rects := classifier.DetectMultiScale(img)
+		fmt.Printf("found %d faces\n", len(rects))
+
+		// draw a rectangle around each face on the original image,
+		// along with text identifing as "Human"
+		for _, r := range rects {
+			gocv.Rectangle(&img, r, blue, 3)
+
+			size := gocv.GetTextSize("Human", gocv.FontHersheyPlain, 1.2, 2)
+			pt := image.Pt(r.Min.X+(r.Min.X/2)-(size.X/2), r.Min.Y-2)
+			gocv.PutText(&img, "Human", pt, gocv.FontHersheyPlain, 1.2, blue, 2)
+		}
+
+		// show the image in the window, and wait 1 millisecond
+		window.IMShow(img)
+		if window.WaitKey(10) >= 0 {
+			break
+		}
+	}
+	return
+}
+
+func ExampleFaceDetection(inputFile, xmlFile string) {
+	w, h := getVideoSize(inputFile)
+	log.Println(w, h)
+
+	pr1, pw1 := io.Pipe()
+	done1 := readProcess(inputFile, pw1)
+	openCvProcess(xmlFile, pr1, w, h)
+	err := <-done1
+	if err != nil {
+		panic(err)
+	}
+	log.Println("Done")
+}