video config construction refactoring

internal/flowdef/flowdef.go

@@ -0,0 +1,143 @@
+// Package flowdef models and validates MXL flow-definition JSON.
+package flowdef
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/google/uuid"
+)
+
+const (
+	FormatVideo   = "urn:x-nmos:format:video"
+	FormatAudio   = "urn:x-nmos:format:audio"
+	MediaTypeV210 = "video/v210"
+
+	InterlaceProgressive = "progressive"
+	ColorSpaceBT709      = "BT709"
+)
+
+type Common struct {
+	Description string              `json:"description"`
+	ID          string              `json:"id"`
+	Tags        map[string][]string `json:"tags"`
+	Format      string              `json:"format"`
+	Label       string              `json:"label"`
+	Parents     []string            `json:"parents"`
+	MediaType   string              `json:"media_type"`
+}
+
+type Rational struct {
+	Numerator   uint `json:"numerator"`
+	Denominator uint `json:"denominator"`
+}
+
+type Video struct {
+	Common
+
+	GrainRate     Rational         `json:"grain_rate"`
+	FrameWidth    uint             `json:"frame_width"`
+	FrameHeight   uint             `json:"frame_height"`
+	InterlaceMode string           `json:"interlace_mode"`
+	ColorSpace    string           `json:"colorspace"`
+	Components    []VideoComponent `json:"components"`
+}
+
+type Audio struct {
+	Common
+
+	SampleRate   Rational `json:"sample_rate"`
+	ChannelCount uint     `json:"channel_count"`
+	BitDepth     uint     `json:"bit_depth"`
+}
+
+type VideoComponent struct {
+	Name     string `json:"name"`
+	Width    uint   `json:"width"`
+	Height   uint   `json:"height"`
+	BitDepth uint   `json:"bit_depth"`
+}
+
+func NewV210Video(id string, width, height uint, rate Rational) (Video, error) {
+	definition := Video{
+		Common: Common{
+			Description: "go-mxl-pattern-gen generated video",
+			ID:          id,
+			Tags: map[string][]string{
+				"urn:x-nmos:tag:grouphint/v1.0": {"go-mxl-pattern-gen:Video"},
+			},
+			Format:    FormatVideo,
+			Label:     "go-mxl-pattern-gen generated video",
+			Parents:   []string{},
+			MediaType: MediaTypeV210,
+		},
+		GrainRate:     rate,
+		FrameWidth:    width,
+		FrameHeight:   height,
+		InterlaceMode: InterlaceProgressive,
+		ColorSpace:    ColorSpaceBT709,
+		Components: []VideoComponent{
+			{Name: "Y", Width: width, Height: height, BitDepth: 10},
+			{Name: "Cb", Width: width / 2, Height: height, BitDepth: 10},
+			{Name: "Cr", Width: width / 2, Height: height, BitDepth: 10},
+		},
+	}
+	if err := definition.Validate(); err != nil {
+		return Video{}, err
+	}
+	return definition, nil
+}
+
+func ParseV210Video(data []byte) (Video, error) {
+	var definition Video
+	if err := json.Unmarshal(data, &definition); err != nil {
+		return Video{}, fmt.Errorf("decode video flow definition: %w", err)
+	}
+	if err := definition.Validate(); err != nil {
+		return Video{}, fmt.Errorf("invalid video flow definition: %w", err)
+	}
+	return definition, nil
+}
+
+func (v Video) Validate() error {
+	if err := uuid.Validate(v.ID); err != nil {
+		return fmt.Errorf("invalid id %q: %w", v.ID, err)
+	}
+	if v.Format != FormatVideo {
+		return fmt.Errorf("format must be %q, got %q", FormatVideo, v.Format)
+	}
+	if v.MediaType != MediaTypeV210 {
+		return fmt.Errorf("media_type must be %q, got %q", MediaTypeV210, v.MediaType)
+	}
+	if v.InterlaceMode != InterlaceProgressive {
+		return fmt.Errorf("interlace_mode must be %q, got %q", InterlaceProgressive, v.InterlaceMode)
+	}
+	if v.ColorSpace != ColorSpaceBT709 {
+		return fmt.Errorf("colorspace must be %q, got %q", ColorSpaceBT709, v.ColorSpace)
+	}
+	if v.FrameWidth == 0 || v.FrameWidth%6 != 0 {
+		return fmt.Errorf("frame_width must be greater than zero and divisible by 6, got %d", v.FrameWidth)
+	}
+	if v.FrameHeight == 0 {
+		return fmt.Errorf("frame_height must be greater than zero")
+	}
+	if v.GrainRate.Numerator == 0 || v.GrainRate.Denominator == 0 {
+		return fmt.Errorf("grain_rate numerator and denominator must be greater than zero, got %d/%d",
+			v.GrainRate.Numerator, v.GrainRate.Denominator)
+	}
+
+	want := []VideoComponent{
+		{Name: "Y", Width: v.FrameWidth, Height: v.FrameHeight, BitDepth: 10},
+		{Name: "Cb", Width: v.FrameWidth / 2, Height: v.FrameHeight, BitDepth: 10},
+		{Name: "Cr", Width: v.FrameWidth / 2, Height: v.FrameHeight, BitDepth: 10},
+	}
+	if len(v.Components) != len(want) {
+		return fmt.Errorf("v210 requires %d components, got %d", len(want), len(v.Components))
+	}
+	for i := range want {
+		if v.Components[i] != want[i] {
+			return fmt.Errorf("component %d must be %+v, got %+v", i, want[i], v.Components[i])
+		}
+	}
+	return nil
+}