fm-rds-tx/internal/stereo/encoder_test.go

package stereo

import (
	"math"
	"testing"

	"github.com/jan/fm-rds-tx/internal/audio"
)

func TestStereoEncoderEncode(t *testing.T) {
	enc := NewStereoEncoder(48000)
	frame := audio.NewFrame(1, -1)
	result := enc.Encode(frame)

	if diff := result.Mono; math.Abs(diff) > 1e-9 {
		t.Fatalf("expected mono 0, got %v", diff)
	}

	expected := 0.75 * ((1 - (-1)) / 2.0)
	if math.Abs(result.Stereo-expected) > 1e-9 {
		t.Fatalf("unexpected stereo level: %v", result.Stereo)
	}

	if result.Pilot < -0.1 || result.Pilot > 0.1 {
		t.Fatalf("pilot sample out of expected range: %v", result.Pilot)
	}
}

func TestStereoEncoderReset(t *testing.T) {
	frame := audio.NewFrame(0.1, -0.1)
	enc := NewStereoEncoder(48000)

	initial := make([]float64, 0, 4)
	for i := 0; i < 4; i++ {
		initial = append(initial, enc.Encode(frame).Pilot)
	}

	enc.Reset()

	afterReset := make([]float64, 0, 4)
	for i := 0; i < 4; i++ {
		afterReset = append(afterReset, enc.Encode(frame).Pilot)
	}

	for i := range initial {
		if math.Abs(initial[i]-afterReset[i]) > 1e-9 {
			t.Fatalf("reset failed at sample %d: %v vs %v", i, initial[i], afterReset[i])
		}
	}
}