install go2rtc on bob

installs_on_host/go2rtc/pkg/y4m/y4m.go

@@ -0,0 +1,149 @@
+package y4m
+
+import (
+	"bytes"
+	"image"
+
+	"github.com/AlexxIT/go2rtc/pkg/core"
+)
+
+const FourCC = "YUV4"
+
+const frameHdr = "FRAME\n"
+
+func ParseHeader(b []byte) (fmtp string) {
+	for b != nil {
+		// YUV4MPEG2 W1280 H720 F24:1 Ip A1:1 C420mpeg2 XYSCSS=420MPEG2
+		// https://manned.org/yuv4mpeg.5
+		// https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/yuv4mpegenc.c
+		key := b[0]
+
+		var value string
+		if i := bytes.IndexByte(b, ' '); i > 0 {
+			value = string(b[1:i])
+			b = b[i+1:]
+		} else {
+			value = string(b[1:])
+			b = nil
+		}
+
+		switch key {
+		case 'W':
+			fmtp = "width=" + value
+		case 'H':
+			fmtp += ";height=" + value
+		case 'C':
+			fmtp += ";colorspace=" + value
+		}
+	}
+	return
+}
+
+func GetSize(fmtp string) int {
+	w := core.Atoi(core.Between(fmtp, "width=", ";"))
+	h := core.Atoi(core.Between(fmtp, "height=", ";"))
+
+	switch core.Between(fmtp, "colorspace=", ";") {
+	case "mono":
+		return w * h
+	case "420mpeg2", "420jpeg":
+		return w * h * 3 / 2
+	case "422":
+		return w * h * 2
+	case "444":
+		return w * h * 3
+	}
+
+	return 0
+}
+
+func NewImage(fmtp string) func(frame []byte) image.Image {
+	w := core.Atoi(core.Between(fmtp, "width=", ";"))
+	h := core.Atoi(core.Between(fmtp, "height=", ";"))
+	rect := image.Rect(0, 0, w, h)
+
+	switch core.Between(fmtp, "colorspace=", ";") {
+	case "mono":
+		return func(frame []byte) image.Image {
+			return &image.Gray{
+				Pix:    frame,
+				Stride: w,
+				Rect:   rect,
+			}
+		}
+	case "420mpeg2", "420jpeg":
+		i1 := w * h
+		i2 := i1 + i1/4
+		i3 := i2 + i1/4
+
+		return func(frame []byte) image.Image {
+			return &image.YCbCr{
+				Y:              frame[:i1],
+				Cb:             frame[i1:i2],
+				Cr:             frame[i2:i3],
+				YStride:        w,
+				CStride:        w / 2,
+				SubsampleRatio: image.YCbCrSubsampleRatio420,
+				Rect:           rect,
+			}
+		}
+	case "422":
+		i1 := w * h
+		i2 := i1 + i1/2
+		i3 := i2 + i1/2
+
+		return func(frame []byte) image.Image {
+			return &image.YCbCr{
+				Y:              frame[:i1],
+				Cb:             frame[i1:i2],
+				Cr:             frame[i2:i3],
+				YStride:        w,
+				CStride:        w / 2,
+				SubsampleRatio: image.YCbCrSubsampleRatio422,
+				Rect:           rect,
+			}
+		}
+	case "444":
+		i1 := w * h
+		i2 := i1 + i1
+		i3 := i2 + i1
+
+		return func(frame []byte) image.Image {
+			return &image.YCbCr{
+				Y:              frame[:i1],
+				Cb:             frame[i1:i2],
+				Cr:             frame[i2:i3],
+				YStride:        w,
+				CStride:        w,
+				SubsampleRatio: image.YCbCrSubsampleRatio444,
+				Rect:           rect,
+			}
+		}
+	}
+
+	return nil
+}
+
+// HasSameColor checks if all pixels has same color
+func HasSameColor(img image.Image) bool {
+	var pix []byte
+
+	switch img := img.(type) {
+	case *image.Gray:
+		pix = img.Pix
+	case *image.YCbCr:
+		pix = img.Y
+	}
+
+	if len(pix) == 0 {
+		return false
+	}
+
+	i0 := pix[0]
+	for _, i := range pix {
+		if i != i0 {
+			return false
+		}
+	}
+	return true
+}