RP219 CPU pattern

internal/generator/cpu_patterns.go

@@ -1,6 +1,8 @@
 package generator
 
-import "fmt"
+import (
+	"fmt"
+)
 
 var ebu75Colors = [...]YCbCr10{
 	{Y: 721, Cb: 512, Cr: 512},
@@ -24,6 +26,16 @@ var ebu100Colors = [...]YCbCr10{
 	{Y: 64, Cb: 512, Cr: 512},
 }
 
+var smpte75Colors = [...]YCbCr10{
+	{Y: 721, Cb: 512, Cr: 512},
+	{Y: 674, Cb: 176, Cr: 543},
+	{Y: 581, Cb: 589, Cr: 176},
+	{Y: 534, Cb: 253, Cr: 207},
+	{Y: 251, Cb: 771, Cr: 817},
+	{Y: 204, Cb: 435, Cr: 848},
+	{Y: 111, Cb: 848, Cr: 481},
+}
+
 var grayBarsColors = [...]YCbCr10{
 	{Y: 64, Cb: 512, Cr: 512},
 	{Y: 137, Cb: 512, Cr: 512},
@@ -58,6 +70,16 @@ func NewCPUPatternGenerator(width, height uint, pattern string) (*CPUGenerator,
 		baseColor = ebu100BaseColor
 	case "ebu100-move":
 		baseColor, dynamic = ebu100BaseColor, true
+	case "smpte":
+		if err := validateRP219Size(width, height); err != nil {
+			return nil, err
+		}
+		baseColor = rp219BaseColor
+	case "smpte-move":
+		if err := validateRP219Size(width, height); err != nil {
+			return nil, err
+		}
+		baseColor, dynamic = rp219BaseColor, true
 	case "gray-bars":
 		baseColor = grayBarsBaseColor
 	case "gray-bars-move":
@@ -117,3 +139,106 @@ func renderBasePattern(dst []byte, width, height int, baseColor baseColorFunc) e
 	}
 	return nil
 }
+
+var (
+	gray40 = YCbCr10{Y: 414, Cb: 512, Cr: 512}
+	gray15 = YCbCr10{Y: 195, Cb: 512, Cr: 512}
+	black  = YCbCr10{Y: 64, Cb: 512, Cr: 512}
+	white  = YCbCr10{Y: 940, Cb: 512, Cr: 512}
+)
+
+func rp219BaseColor(x, y, width, height int) YCbCr10 {
+	barsWidth := (height / 3) * 4
+	barsStart := (width - barsWidth) / 2
+	barsEnd := barsStart + barsWidth
+	oneBarWidth := barsWidth / 7
+
+	unitH := height / 12
+	section1End := unitH * 7
+	section2End := section1End + unitH
+	section3End := section2End + unitH
+
+	rampStart := barsStart + oneBarWidth
+	rampEnd := barsEnd
+	rampWidth := rampEnd - rampStart
+
+	switch {
+	case y < section1End:
+		if x < barsStart || x >= barsEnd {
+			return gray40
+		}
+
+		bar := min(
+			(x-barsStart)*len(smpte75Colors)/barsWidth,
+			len(smpte75Colors)-1,
+		)
+		return smpte75Colors[bar]
+
+	case y < section2End:
+		switch {
+		case x < barsStart:
+			return YCbCr10{Y: 754, Cb: 615, Cr: 64} // 100% cyan
+		case x < rampStart:
+			return YCbCr10{Y: 244, Cb: 612, Cr: 395} // -I
+		case x >= barsEnd:
+			return YCbCr10{Y: 127, Cb: 960, Cr: 471} // 100% blue
+		default:
+			return YCbCr10{Y: 721, Cb: 512, Cr: 512} // 75% white
+		}
+
+	case y < section3End:
+		switch {
+		case x < barsStart:
+			return YCbCr10{Y: 877, Cb: 64, Cr: 553} // 100% yellow
+		case x < rampStart:
+			return YCbCr10{Y: 141, Cb: 697, Cr: 606} // +Q
+		case x >= barsEnd:
+			return YCbCr10{Y: 250, Cb: 409, Cr: 960} // 75% red
+		default:
+			rampY := 64 + ((x-rampStart)*876)/rampWidth
+			return YCbCr10{Y: uint32(rampY), Cb: 512, Cr: 512}
+		}
+
+	default:
+		if x < barsStart || x >= barsEnd {
+			return gray15
+		}
+
+		bar := (x - barsStart) / oneBarWidth
+		switch {
+		case bar == 1:
+			return white
+		case bar == 3:
+			offset := (x - barsStart) % oneBarWidth
+			subBar := offset * 3 / oneBarWidth
+
+			switch subBar {
+			case 0:
+				return YCbCr10{Y: 46, Cb: 512, Cr: 512}
+			case 1:
+				return black
+			default:
+				return YCbCr10{Y: 82, Cb: 512, Cr: 512}
+			}
+
+		default:
+			return black
+		}
+	}
+}
+
+func validateRP219Size(width, height uint) error {
+	if height < 12 {
+		return fmt.Errorf("cpu RP 219 requires frame height of at least 12, got %d", height)
+	}
+	barsWidth := (height / 3) * 4
+	if barsWidth < 7 || width < barsWidth {
+		return fmt.Errorf(
+			"cpu RP 219 requires frame width %d to fit a 4:3 pattern area for height %d, got %d",
+			barsWidth,
+			height,
+			width,
+		)
+	}
+	return nil
+}