improve examples (#708)

examples/client-record-format-h264/dummy_image.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"image"
+	"image/color"
+)
+
+var dummyImageCount = 0
+
+func createDummyImage() *image.RGBA {
+	img := image.NewRGBA(image.Rect(0, 0, 640, 480))
+
+	var cl color.RGBA
+	switch dummyImageCount {
+	case 0:
+		cl = color.RGBA{255, 0, 0, 0}
+	case 1:
+		cl = color.RGBA{0, 255, 0, 0}
+	case 2:
+		cl = color.RGBA{0, 0, 255, 0}
+	}
+	dummyImageCount = (dummyImageCount + 1) % 3
+
+	for y := 0; y < img.Rect.Dy(); y++ {
+		for x := 0; x < img.Rect.Dx(); x++ {
+			img.SetRGBA(x, y, cl)
+		}
+	}
+
+	return img
+}