faster !

drivers/video/ppm.go

@@ -3,7 +3,7 @@ package video
 import (
 	"context"
 	"image"
-	"image/color"
+	"image/draw"
 	"io"
 	"time"
 
@@ -58,7 +58,7 @@ func (v *PPMStreamDriver) Properties() []prop.Media {
 
 func (v *PPMStreamDriver) VideoRecord(p prop.Media) (video.Reader, error) {
 	logrus.Debug(p)
-	canvas := image.NewYCbCr(
+	/*canvas := image.NewYCbCr(
 		image.Rect(0, 0, p.Width, p.Height),
 		image.YCbCrSubsampleRatio420,
 	)
@@ -70,7 +70,12 @@ func (v *PPMStreamDriver) VideoRecord(p prop.Media) (video.Reader, error) {
 			canvas.Cb[canvas.COffset(x, y)] = Cb
 			canvas.Cr[canvas.COffset(x, y)] = Cr
 		}
-	}
+	}*/
+
+	canvas := image.NewRGBA(image.Rect(0, 0, p.Width, p.Height))
+	var (
+		prevHeight, prevWidth int
+	)
 
 	r := video.ReaderFunc(func() (img image.Image, release func(), err error) {
 		select {
@@ -79,30 +84,30 @@ func (v *PPMStreamDriver) VideoRecord(p prop.Media) (video.Reader, error) {
 		case ppmF := <-v.PPMImage:
 			defer ppmF.Image.Close()
 
+			// skip timeouted frame
+			if time.Since(ppmF.Time) > time.Second/time.Duration(p.FrameRate) {
+				return canvas, func() {}, nil
+			}
+
 			img, _, err := image.Decode(ppmF.Image)
 			if err != nil {
 				return nil, func() {}, err
 			}
 
-			// resize image and draw it to canvas
-			//resized := resize.Resize(uint(p.Width), uint(p.Height), img, resize.Bilinear)
+			// screen geometroy change
+			if img.Bounds().Dx() != prevWidth || img.Bounds().Dy() != prevHeight {
+				draw.Draw(canvas, canvas.Rect, image.Black, image.Black.Bounds().Min, draw.Over)
+				prevWidth = img.Bounds().Dx()
+				prevHeight = img.Bounds().Dy()
+			}
+
 			offsetX := (canvas.Rect.Dx() - img.Bounds().Dx()) / 2
 			offsetY := (canvas.Rect.Dy() - img.Bounds().Dy()) / 2
 
-			for y := 0; y < img.Bounds().Dy(); y++ {
-				for x := 0; x < img.Bounds().Dx(); x++ {
-					r, g, b, _ := img.At(x, y).RGBA()
-
-					Y, Cb, Cr := color.RGBToYCbCr(uint8(r), uint8(g), uint8(b))
-
-					_x := offsetX + x
-					_y := offsetY + y
-
-					canvas.Y[canvas.YOffset(_x, _y)] = Y
-					canvas.Cb[canvas.COffset(_x, _y)] = Cb
-					canvas.Cr[canvas.COffset(_x, _y)] = Cr
-				}
-			}
+			draw.Draw(canvas, image.Rect(
+				offsetX, offsetY, offsetX+img.Bounds().Dx(), offsetY+img.Bounds().Dy(),
+			), img, img.Bounds().Min, draw.Over)
+		case <-time.After(time.Second / time.Duration(p.FrameRate)):
 		default:
 		}
 		return canvas, func() {}, nil