audio is prepared, next is MXL part

cmd/mxl-pattern/main.go

@@ -20,6 +20,7 @@ import (
 	"github.com/qvest-digital/go-mxl/mxl"
 	"github.com/spf13/pflag"
 
+	"mxl-pattern-generator/internal/audio"
 	"mxl-pattern-generator/internal/flowdef"
 	"mxl-pattern-generator/internal/generator"
 	"mxl-pattern-generator/internal/video"
@@ -51,6 +52,7 @@ type appArgs struct {
 
 	audioChannels     uint8
 	audioSamplingFreq string
+	audioLevel        string
 	audioUUID         string
 }
 
@@ -159,7 +161,17 @@ func validateVideoArgs(args *appArgs) error {
 }
 
 func validateAudioArgs(args *appArgs) error {
-	if args.audioFlowDefFile != "" || args.audioChannels == 0 {
+	if args.audioFlowDefFile == "" && args.audioChannels == 0 {
+		return nil
+	}
+	if _, ok := audioLevels[args.audioLevel]; !ok {
+		return fmt.Errorf(
+			"unsupported audio level %q (supported: %s)",
+			args.audioLevel,
+			sortedMapKeys(audioLevels),
+		)
+	}
+	if args.audioFlowDefFile != "" {
 		return nil
 	}
 	if _, exists := samplingRates[args.audioSamplingFreq]; !exists {
@@ -271,6 +283,11 @@ var patterns = map[string]pattern{
 	},
 }
 
+var audioLevels = map[string]float64{
+	"ebu":   audio.LevelEBUDBFS,
+	"smpte": audio.LevelSMPTEDBFS,
+}
+
 func listPatterns(w io.Writer) {
 	fmt.Fprintln(w, "List of available video patterns:")
 	names := make([]string, 0, len(patterns))
@@ -326,9 +343,10 @@ func addFlags(fs *pflag.FlagSet, args *appArgs) {
 	fs.StringVar(&args.videoFPS, "fps", "25", "Video pattern FPS")
 	fs.StringVar(&args.videoUUID, "video-id", "", "Video UUID. Will be created, if not provided")
 	// Audio pattern flags
-	fs.Uint8VarP(&args.audioChannels, "channel", "c", 0, "Amount of audio channels. Each channel: num * 1kHz. Zero = no sound [TODO]")
+	fs.Uint8VarP(&args.audioChannels, "channel", "c", 0, "Amount of audio channels. Each channel: num * 1kHz")
-	fs.StringVarP(&args.audioSamplingFreq, "freq", "f", "48", "Sampling frequency of test audio feed in kHz [TODO]")
+	fs.StringVarP(&args.audioSamplingFreq, "freq", "f", "48", "Sampling frequency of test audio feed in kHz")
-	fs.StringVar(&args.audioUUID, "audio-id", "", "Audio UUID. Will be created, if not provided [TODO]")
+	fs.StringVar(&args.audioLevel, "audio-level", "ebu", "Audio alignment level: ebu (-18 dBFS) or smpte (-20 dBFS)")
+	fs.StringVar(&args.audioUUID, "audio-id", "", "Audio UUID. Will be created, if not provided")
 }
 
 func parseArgs(argv []string, stdout, stderr io.Writer) (parseResult, error) {
@@ -418,6 +436,49 @@ func buildVideoConfig(args appArgs) (video.Config, error) {
 	}, nil
 }
 
+// buildAudioConfig returns nil when audio is disabled. An explicit audio flow
+// definition enables audio even when --channel is zero.
+func buildAudioConfig(args appArgs) (*audio.Config, error) {
+	if args.audioFlowDefFile == "" && args.audioChannels == 0 {
+		return nil, nil
+	}
+	levelDBFS, ok := audioLevels[args.audioLevel]
+	if !ok {
+		return nil, fmt.Errorf("unsupported audio level %q", args.audioLevel)
+	}
+
+	var definition flowdef.Audio
+	if args.audioFlowDefFile != "" {
+		data, err := os.ReadFile(args.audioFlowDefFile)
+		if err != nil {
+			return nil, fmt.Errorf("read audio flow definition %q: %w", args.audioFlowDefFile, err)
+		}
+		definition, err = flowdef.ParseFloat32Audio(data)
+		if err != nil {
+			return nil, fmt.Errorf("parse audio flow definition %q: %w", args.audioFlowDefFile, err)
+		}
+	} else {
+		rate, ok := samplingRates[args.audioSamplingFreq]
+		if !ok {
+			return nil, fmt.Errorf("unsupported audio sample rate %q", args.audioSamplingFreq)
+		}
+		var err error
+		definition, err = flowdef.NewFloat32Audio(
+			args.audioUUID,
+			uint(args.audioChannels),
+			flowdef.Rational{Numerator: uint(rate.Num), Denominator: uint(rate.Den)},
+		)
+		if err != nil {
+			return nil, fmt.Errorf("build audio flow definition: %w", err)
+		}
+	}
+
+	return &audio.Config{
+		Definition: definition,
+		LevelDBFS:  levelDBFS,
+	}, nil
+}
+
 func main() {
 	parsed, err := parseArgs(os.Args[1:], os.Stdout, os.Stderr)
 	if err != nil {

cmd/mxl-pattern/main_test.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 	"testing"
 
+	"mxl-pattern-generator/internal/audio"
 	"mxl-pattern-generator/internal/flowdef"
 )
 
@@ -162,3 +163,90 @@ func TestBuildVideoConfigFromFile(t *testing.T) {
 		t.Fatalf("rate = %d/%d, want file value 60000/1001", cfg.Rate().Num, cfg.Rate().Den)
 	}
 }
+
+func TestBuildAudioConfigDisabled(t *testing.T) {
+	cfg, err := buildAudioConfig(appArgs{})
+	if err != nil {
+		t.Fatalf("buildAudioConfig: %v", err)
+	}
+	if cfg != nil {
+		t.Fatalf("config = %+v, want nil for disabled audio", cfg)
+	}
+}
+
+func TestBuildAudioConfigFromArgs(t *testing.T) {
+	cfg, err := buildAudioConfig(appArgs{
+		audioUUID:         "b3bb5be7-9fe9-4324-a5bb-4c70e1084449",
+		audioChannels:     2,
+		audioSamplingFreq: "48",
+		audioLevel:        "ebu",
+	})
+	if err != nil {
+		t.Fatalf("buildAudioConfig: %v", err)
+	}
+	if cfg == nil {
+		t.Fatal("config is nil")
+	}
+	if cfg.Channels() != 2 {
+		t.Fatalf("channels = %d, want 2", cfg.Channels())
+	}
+	if cfg.Rate().Num != 48000 || cfg.Rate().Den != 1 {
+		t.Fatalf("rate = %d/%d, want 48000/1", cfg.Rate().Num, cfg.Rate().Den)
+	}
+	if cfg.LevelDBFS != audio.LevelEBUDBFS {
+		t.Fatalf("level = %.2f dBFS, want %.2f dBFS", cfg.LevelDBFS, audio.LevelEBUDBFS)
+	}
+}
+
+func TestBuildAudioConfigFromFile(t *testing.T) {
+	definition, err := flowdef.NewFloat32Audio(
+		"b3bb5be7-9fe9-4324-a5bb-4c70e1084449",
+		8,
+		flowdef.Rational{Numerator: 96000, Denominator: 1},
+	)
+	if err != nil {
+		t.Fatalf("NewFloat32Audio: %v", err)
+	}
+	data, err := json.Marshal(definition)
+	if err != nil {
+		t.Fatalf("json.Marshal: %v", err)
+	}
+	path := t.TempDir() + "/audio.json"
+	if err := os.WriteFile(path, data, 0o600); err != nil {
+		t.Fatalf("os.WriteFile: %v", err)
+	}
+
+	cfg, err := buildAudioConfig(appArgs{
+		audioFlowDefFile:  path,
+		audioChannels:     2,
+		audioSamplingFreq: "48",
+		audioLevel:        "smpte",
+	})
+	if err != nil {
+		t.Fatalf("buildAudioConfig: %v", err)
+	}
+	if cfg == nil {
+		t.Fatal("config is nil")
+	}
+	if cfg.Channels() != 8 {
+		t.Fatalf("channels = %d, want file value 8", cfg.Channels())
+	}
+	if cfg.Rate().Num != 96000 || cfg.Rate().Den != 1 {
+		t.Fatalf("rate = %d/%d, want file value 96000/1", cfg.Rate().Num, cfg.Rate().Den)
+	}
+	if cfg.LevelDBFS != audio.LevelSMPTEDBFS {
+		t.Fatalf("level = %.2f dBFS, want %.2f dBFS", cfg.LevelDBFS, audio.LevelSMPTEDBFS)
+	}
+}
+
+func TestValidateAudioArgsRejectsUnknownLevelForFlowDefinition(t *testing.T) {
+	args := appArgs{
+		audioFlowDefFile: "audio.json",
+		audioLevel:       "unknown",
+	}
+
+	err := validateAudioArgs(&args)
+	if err == nil || !strings.Contains(err.Error(), "unsupported audio level") {
+		t.Fatalf("error = %v, want unsupported audio level error", err)
+	}
+}

internal/audio/config.go

@@ -0,0 +1,32 @@
+package audio
+
+import (
+	"mxl-pattern-generator/internal/flowdef"
+
+	"github.com/qvest-digital/go-mxl/mxl"
+)
+
+const (
+	LevelEBUDBFS   = -18.0
+	LevelSMPTEDBFS = -20.0
+)
+
+type Config struct {
+	Definition flowdef.Audio
+	LevelDBFS  float64
+}
+
+func (c Config) ID() string {
+	return c.Definition.ID
+}
+
+func (c Config) Channels() uint {
+	return c.Definition.ChannelCount
+}
+
+func (c Config) Rate() mxl.Rational {
+	return mxl.Rational{
+		Num: int64(c.Definition.SampleRate.Numerator),
+		Den: int64(c.Definition.SampleRate.Denominator),
+	}
+}

internal/audio/generator.go

@@ -0,0 +1,122 @@
+package audio
+
+import (
+	"encoding/binary"
+	"fmt"
+	"math"
+)
+
+type Generator interface {
+	// Generate fills consecutive float32 sample fragments for one channel.
+	// firstSample is the absolute MXL sample index, so phase does not depend on
+	// batch or ring-buffer boundaries.
+	Generate(channel uint, firstSample uint64, fragments ...[]byte) error
+}
+
+type SineGenerator struct {
+	channels      uint
+	sampleRate    float64
+	baseFrequency float64
+	amplitude     float32
+}
+
+func NewSineGenerator(
+	cfg Config,
+	baseFrequency float64,
+) (*SineGenerator, error) {
+	if cfg.Channels() == 0 {
+		return nil, fmt.Errorf("channel count must be greater than zero")
+	}
+	rate := cfg.Rate()
+	if rate.Num <= 0 || rate.Den <= 0 {
+		return nil, fmt.Errorf(
+			"sample rate numerator and denominator must be greater than zero, got %d/%d",
+			rate.Num,
+			rate.Den,
+		)
+	}
+	if math.IsNaN(baseFrequency) || math.IsInf(baseFrequency, 0) || baseFrequency <= 0 {
+		return nil, fmt.Errorf("base frequency must be finite and greater than zero, got %g", baseFrequency)
+	}
+
+	sampleRate := float64(rate.Num) / float64(rate.Den)
+	highestFrequency := float64(cfg.Channels()) * baseFrequency
+	nyquist := sampleRate / 2
+	if highestFrequency >= nyquist {
+		return nil, fmt.Errorf(
+			"highest tone frequency %.0f Hz must be below Nyquist frequency %.0f Hz",
+			highestFrequency,
+			nyquist,
+		)
+	}
+
+	if math.IsNaN(cfg.LevelDBFS) || math.IsInf(cfg.LevelDBFS, 0) {
+		return nil, fmt.Errorf("audio level must be finite")
+	}
+	if cfg.LevelDBFS > 0 {
+		return nil, fmt.Errorf(
+			"audio level must not exceed 0 dBFS, got %.2f",
+			cfg.LevelDBFS,
+		)
+	}
+	if cfg.LevelDBFS < -100 {
+		return nil, fmt.Errorf(
+			"audio level must be at least -100 dBFS, got %.2f dBFS",
+			cfg.LevelDBFS,
+		)
+	}
+
+	amplitude := math.Pow(10, cfg.LevelDBFS/20)
+	return &SineGenerator{
+		channels:      cfg.Channels(),
+		sampleRate:    sampleRate,
+		baseFrequency: baseFrequency,
+		amplitude:     float32(amplitude),
+	}, nil
+}
+
+func (g *SineGenerator) Generate(
+	channel uint,
+	firstSample uint64,
+	fragments ...[]byte,
+) error {
+	if channel >= g.channels {
+		return fmt.Errorf(
+			"audio channel %d is out of range [0, %d)",
+			channel,
+			g.channels,
+		)
+	}
+
+	frequency := float64(channel+1) * g.baseFrequency
+	sampleIndex := firstSample
+
+	for fragmentIndex, fragment := range fragments {
+		if len(fragment)%4 != 0 {
+			return fmt.Errorf(
+				"audio fragment %d has %d bytes; float32 data requires a multiple of 4",
+				fragmentIndex,
+				len(fragment),
+			)
+		}
+	}
+
+	for _, fragment := range fragments {
+		for offset := 0; offset < len(fragment); offset += 4 {
+			phase := 2 * math.Pi *
+				frequency *
+				float64(sampleIndex) /
+				g.sampleRate
+
+			sample := g.amplitude * float32(math.Sin(phase))
+
+			binary.LittleEndian.PutUint32(
+				fragment[offset:offset+4],
+				math.Float32bits(sample),
+			)
+			sampleIndex++
+		}
+	}
+
+	return nil
+}

internal/audio/generator_test.go

@@ -0,0 +1,155 @@
+package audio
+
+import (
+	"bytes"
+	"encoding/binary"
+	"math"
+	"testing"
+
+	"mxl-pattern-generator/internal/flowdef"
+)
+
+const testAudioID = "b3bb5be7-9fe9-4324-a5bb-4c70e1084449"
+
+func testConfig(t *testing.T, channels uint, rate flowdef.Rational, level float64) Config {
+	t.Helper()
+	definition, err := flowdef.NewFloat32Audio(testAudioID, channels, rate)
+	if err != nil {
+		t.Fatalf("NewFloat32Audio: %v", err)
+	}
+	return Config{Definition: definition, LevelDBFS: level}
+}
+
+func decodeSample(data []byte, index int) float32 {
+	return math.Float32frombits(binary.LittleEndian.Uint32(data[index*4:]))
+}
+
+func requireSampleNear(t *testing.T, got, want float32) {
+	t.Helper()
+	if math.Abs(float64(got-want)) > 1e-6 {
+		t.Fatalf("sample = %.8f, want %.8f", got, want)
+	}
+}
+
+func TestNewSineGeneratorValidation(t *testing.T) {
+	valid := testConfig(t, 2, flowdef.Rational{Numerator: 48000, Denominator: 1}, LevelEBUDBFS)
+
+	tests := []struct {
+		name    string
+		cfg     Config
+		baseHz  float64
+		wantErr bool
+	}{
+		{name: "valid", cfg: valid, baseHz: 1000},
+		{name: "zero channels", cfg: Config{Definition: flowdef.Audio{SampleRate: flowdef.Rational{Numerator: 48000, Denominator: 1}}, LevelDBFS: LevelEBUDBFS}, baseHz: 1000, wantErr: true},
+		{name: "zero numerator", cfg: Config{Definition: flowdef.Audio{SampleRate: flowdef.Rational{Denominator: 1}, ChannelCount: 1}, LevelDBFS: LevelEBUDBFS}, baseHz: 1000, wantErr: true},
+		{name: "zero denominator", cfg: Config{Definition: flowdef.Audio{SampleRate: flowdef.Rational{Numerator: 48000}, ChannelCount: 1}, LevelDBFS: LevelEBUDBFS}, baseHz: 1000, wantErr: true},
+		{name: "zero base", cfg: valid, baseHz: 0, wantErr: true},
+		{name: "NaN base", cfg: valid, baseHz: math.NaN(), wantErr: true},
+		{name: "NaN level", cfg: Config{Definition: valid.Definition, LevelDBFS: math.NaN()}, baseHz: 1000, wantErr: true},
+		{name: "above full scale", cfg: Config{Definition: valid.Definition, LevelDBFS: 1}, baseHz: 1000, wantErr: true},
+		{name: "too quiet", cfg: Config{Definition: valid.Definition, LevelDBFS: -101}, baseHz: 1000, wantErr: true},
+		{name: "Nyquist", cfg: testConfig(t, 24, flowdef.Rational{Numerator: 48000, Denominator: 1}, LevelEBUDBFS), baseHz: 1000, wantErr: true},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			_, err := NewSineGenerator(tc.cfg, tc.baseHz)
+			if (err != nil) != tc.wantErr {
+				t.Fatalf("error = %v, wantErr %v", err, tc.wantErr)
+			}
+		})
+	}
+}
+
+func TestNewSineGeneratorPreservesRationalSampleRate(t *testing.T) {
+	cfg := testConfig(t, 1, flowdef.Rational{Numerator: 48000, Denominator: 1001}, LevelEBUDBFS)
+	gen, err := NewSineGenerator(cfg, 1)
+	if err != nil {
+		t.Fatalf("NewSineGenerator: %v", err)
+	}
+	want := 48000.0 / 1001.0
+	if math.Abs(gen.sampleRate-want) > 1e-12 {
+		t.Fatalf("sample rate = %.12f, want %.12f", gen.sampleRate, want)
+	}
+}
+
+func TestSineGeneratorKnownSamplesAndChannels(t *testing.T) {
+	cfg := testConfig(t, 2, flowdef.Rational{Numerator: 48000, Denominator: 1}, LevelSMPTEDBFS)
+	gen, err := NewSineGenerator(cfg, 1000)
+	if err != nil {
+		t.Fatalf("NewSineGenerator: %v", err)
+	}
+
+	channel0 := make([]byte, 37*4)
+	if err := gen.Generate(0, 0, channel0); err != nil {
+		t.Fatalf("Generate channel 0: %v", err)
+	}
+	requireSampleNear(t, decodeSample(channel0, 0), 0)
+	requireSampleNear(t, decodeSample(channel0, 12), 0.1)
+	requireSampleNear(t, decodeSample(channel0, 24), 0)
+	requireSampleNear(t, decodeSample(channel0, 36), -0.1)
+
+	channel1 := make([]byte, 7*4)
+	if err := gen.Generate(1, 0, channel1); err != nil {
+		t.Fatalf("Generate channel 1: %v", err)
+	}
+	requireSampleNear(t, decodeSample(channel1, 6), 0.1)
+}
+
+func TestSineGeneratorUsesConfiguredBaseFrequency(t *testing.T) {
+	cfg := testConfig(t, 1, flowdef.Rational{Numerator: 48000, Denominator: 1}, LevelEBUDBFS)
+	gen, err := NewSineGenerator(cfg, 2000)
+	if err != nil {
+		t.Fatalf("NewSineGenerator: %v", err)
+	}
+
+	data := make([]byte, 7*4)
+	if err := gen.Generate(0, 0, data); err != nil {
+		t.Fatalf("Generate: %v", err)
+	}
+	wantPeak := float32(math.Pow(10, LevelEBUDBFS/20))
+	requireSampleNear(t, decodeSample(data, 6), wantPeak)
+}
+
+func TestSineGeneratorFragmentContinuity(t *testing.T) {
+	cfg := testConfig(t, 1, flowdef.Rational{Numerator: 48000, Denominator: 1}, LevelEBUDBFS)
+	gen, err := NewSineGenerator(cfg, 1000)
+	if err != nil {
+		t.Fatalf("NewSineGenerator: %v", err)
+	}
+
+	whole := make([]byte, 40*4)
+	if err := gen.Generate(0, 100, whole); err != nil {
+		t.Fatalf("Generate whole: %v", err)
+	}
+	first := make([]byte, 13*4)
+	second := make([]byte, 27*4)
+	if err := gen.Generate(0, 100, first, second); err != nil {
+		t.Fatalf("Generate fragments: %v", err)
+	}
+	joined := append(append([]byte(nil), first...), second...)
+	if !bytes.Equal(joined, whole) {
+		t.Fatal("fragmented output differs from contiguous output")
+	}
+}
+
+func TestSineGeneratorRejectsInvalidInputWithoutWriting(t *testing.T) {
+	cfg := testConfig(t, 1, flowdef.Rational{Numerator: 48000, Denominator: 1}, LevelEBUDBFS)
+	gen, err := NewSineGenerator(cfg, 1000)
+	if err != nil {
+		t.Fatalf("NewSineGenerator: %v", err)
+	}
+
+	first := bytes.Repeat([]byte{0xAA}, 8)
+	before := append([]byte(nil), first...)
+	if err := gen.Generate(0, 0, first, make([]byte, 3)); err == nil {
+		t.Fatal("Generate accepted a misaligned fragment")
+	}
+	if !bytes.Equal(first, before) {
+		t.Fatal("Generate modified data before reporting an invalid fragment")
+	}
+	if err := gen.Generate(1, 0, make([]byte, 4)); err == nil {
+		t.Fatal("Generate accepted an out-of-range channel")
+	}
+}

internal/flowdef/flowdef.go

@@ -12,6 +12,7 @@ const (
 	FormatVideo      = "urn:x-nmos:format:video"
 	FormatAudio      = "urn:x-nmos:format:audio"
 	MediaTypeV210    = "video/v210"
+	MediaTypeFloat32 = "audio/float32"
 
 	InterlaceProgressive = "progressive"
 	ColorSpaceBT709      = "BT709"
@@ -32,6 +33,22 @@ type Rational struct {
 	Denominator uint `json:"denominator"`
 }
 
+func (r *Rational) UnmarshalJSON(data []byte) error {
+	var value struct {
+		Numerator   uint  `json:"numerator"`
+		Denominator *uint `json:"denominator"`
+	}
+	if err := json.Unmarshal(data, &value); err != nil {
+		return err
+	}
+	r.Numerator = value.Numerator
+	r.Denominator = 1
+	if value.Denominator != nil {
+		r.Denominator = *value.Denominator
+	}
+	return nil
+}
+
 type Video struct {
 	Common
 
@@ -141,3 +158,66 @@ func (v Video) Validate() error {
 	}
 	return nil
 }
+
+func NewFloat32Audio(
+	id string,
+	channels uint,
+	rate Rational,
+) (Audio, error) {
+	definition := Audio{
+		Common: Common{
+			Description: "go-mxl-pattern-gen generated audio",
+			ID:          id,
+			Tags: map[string][]string{
+				"urn:x-nmos:tag:grouphint/v1.0": {
+					"go-mxl-pattern-gen:Audio",
+				},
+			},
+			Format:    FormatAudio,
+			Label:     "go-mxl-pattern-gen generated audio",
+			Parents:   []string{},
+			MediaType: MediaTypeFloat32,
+		},
+		SampleRate:   rate,
+		ChannelCount: channels,
+		BitDepth:     32,
+	}
+	if err := definition.Validate(); err != nil {
+		return Audio{}, err
+	}
+	return definition, nil
+}
+
+func (a Audio) Validate() error {
+	if err := uuid.Validate(a.ID); err != nil {
+		return fmt.Errorf("invalid id %q: %w", a.ID, err)
+	}
+	if a.Format != FormatAudio {
+		return fmt.Errorf("format must be %q, got %q", FormatAudio, a.Format)
+	}
+	if a.MediaType != MediaTypeFloat32 {
+		return fmt.Errorf("media_type must be %q, got %q", MediaTypeFloat32, a.MediaType)
+	}
+	if a.ChannelCount == 0 {
+		return fmt.Errorf("channel_count must be greater than zero")
+	}
+	if a.SampleRate.Numerator == 0 || a.SampleRate.Denominator == 0 {
+		return fmt.Errorf("sample_rate numerator and denominator must be greater than zero, got %d/%d",
+			a.SampleRate.Numerator, a.SampleRate.Denominator)
+	}
+	if a.BitDepth != 32 {
+		return fmt.Errorf("bit_depth must be 32, got %d", a.BitDepth)
+	}
+	return nil
+}
+
+func ParseFloat32Audio(data []byte) (Audio, error) {
+	var definition Audio
+	if err := json.Unmarshal(data, &definition); err != nil {
+		return Audio{}, fmt.Errorf("decode audio flow definition: %w", err)
+	}
+	if err := definition.Validate(); err != nil {
+		return Audio{}, fmt.Errorf("invalid audio flow definition: %w", err)
+	}
+	return definition, nil
+}

internal/flowdef/flowdef_test.go

@@ -7,6 +7,7 @@ import (
 )
 
 const testVideoID = "5fbec3b1-1b0f-417d-9059-8b94a47197ed"
+const testAudioID = "b3bb5be7-9fe9-4324-a5bb-4c70e1084449"
 
 func TestNewV210Video(t *testing.T) {
 	definition, err := NewV210Video(testVideoID, 1920, 1080, Rational{Numerator: 30000, Denominator: 1001})
@@ -65,3 +66,113 @@ func TestParseV210VideoRejectsAudio(t *testing.T) {
 		t.Fatalf("error = %v, want video format error", err)
 	}
 }
+
+func TestNewFloat32Audio(t *testing.T) {
+	definition, err := NewFloat32Audio(testAudioID, 2, Rational{Numerator: 48000, Denominator: 1})
+	if err != nil {
+		t.Fatalf("NewFloat32Audio: %v", err)
+	}
+	if definition.ID != testAudioID {
+		t.Fatalf("ID = %q, want %q", definition.ID, testAudioID)
+	}
+	if definition.Format != FormatAudio || definition.MediaType != MediaTypeFloat32 {
+		t.Fatalf("format/media type = %q/%q", definition.Format, definition.MediaType)
+	}
+	if definition.ChannelCount != 2 || definition.BitDepth != 32 {
+		t.Fatalf("channels/bit depth = %d/%d, want 2/32", definition.ChannelCount, definition.BitDepth)
+	}
+	if definition.SampleRate != (Rational{Numerator: 48000, Denominator: 1}) {
+		t.Fatalf("sample rate = %+v, want 48000/1", definition.SampleRate)
+	}
+	if definition.Parents == nil {
+		t.Fatal("Parents is nil; want an empty JSON array")
+	}
+}
+
+func TestNewFloat32AudioRejectsZeroChannels(t *testing.T) {
+	_, err := NewFloat32Audio(testAudioID, 0, Rational{Numerator: 48000, Denominator: 1})
+	if err == nil || !strings.Contains(err.Error(), "channel_count") {
+		t.Fatalf("error = %v, want channel_count error", err)
+	}
+}
+
+func TestNewFloat32AudioRejectsInvalidRate(t *testing.T) {
+	_, err := NewFloat32Audio(testAudioID, 2, Rational{Numerator: 48000, Denominator: 0})
+	if err == nil || !strings.Contains(err.Error(), "sample_rate") {
+		t.Fatalf("error = %v, want sample_rate error", err)
+	}
+}
+
+func TestParseFloat32Audio(t *testing.T) {
+	want, err := NewFloat32Audio(testAudioID, 2, Rational{Numerator: 48000, Denominator: 1})
+	if err != nil {
+		t.Fatalf("NewFloat32Audio: %v", err)
+	}
+	data, err := json.Marshal(want)
+	if err != nil {
+		t.Fatalf("json.Marshal: %v", err)
+	}
+
+	got, err := ParseFloat32Audio(data)
+	if err != nil {
+		t.Fatalf("ParseFloat32Audio: %v", err)
+	}
+	if got.ID != want.ID || got.ChannelCount != want.ChannelCount || got.SampleRate != want.SampleRate {
+		t.Fatalf("parsed definition = %+v, want %+v", got, want)
+	}
+}
+
+func TestParseFloat32AudioDefaultsDenominator(t *testing.T) {
+	data := []byte(`{
+		"description":"test audio",
+		"id":"b3bb5be7-9fe9-4324-a5bb-4c70e1084449",
+		"tags":{},
+		"format":"urn:x-nmos:format:audio",
+		"label":"test audio",
+		"parents":[],
+		"media_type":"audio/float32",
+		"sample_rate":{"numerator":48000},
+		"channel_count":2,
+		"bit_depth":32
+	}`)
+
+	definition, err := ParseFloat32Audio(data)
+	if err != nil {
+		t.Fatalf("ParseFloat32Audio: %v", err)
+	}
+	if definition.SampleRate.Denominator != 1 {
+		t.Fatalf("denominator = %d, want implicit 1", definition.SampleRate.Denominator)
+	}
+}
+
+func TestParseFloat32AudioRejectsExplicitZeroDenominator(t *testing.T) {
+	data := []byte(`{
+		"id":"b3bb5be7-9fe9-4324-a5bb-4c70e1084449",
+		"format":"urn:x-nmos:format:audio",
+		"media_type":"audio/float32",
+		"sample_rate":{"numerator":48000,"denominator":0},
+		"channel_count":2,
+		"bit_depth":32
+	}`)
+
+	_, err := ParseFloat32Audio(data)
+	if err == nil || !strings.Contains(err.Error(), "sample_rate") {
+		t.Fatalf("error = %v, want sample_rate error", err)
+	}
+}
+
+func TestParseFloat32AudioRejectsVideo(t *testing.T) {
+	definition, err := NewV210Video(testVideoID, 1920, 1080, Rational{Numerator: 25, Denominator: 1})
+	if err != nil {
+		t.Fatalf("NewV210Video: %v", err)
+	}
+	data, err := json.Marshal(definition)
+	if err != nil {
+		t.Fatalf("json.Marshal: %v", err)
+	}
+
+	_, err = ParseFloat32Audio(data)
+	if err == nil || !strings.Contains(err.Error(), "format must be") {
+		t.Fatalf("error = %v, want audio format error", err)
+	}
+}