gurix
c9794cd4cd
- PanGains uses cos/sin constant-power pan law (D-11) - StereoFramesToInt16Bytes converts stereo frames to interleaved LE int16 bytes - clamp prevents int16 overflow for values outside [-1.0, 1.0] - All 7 mixer tests pass (pan law, byte conversion, clamping)
97 lines
2.6 KiB
Go
97 lines
2.6 KiB
Go
package synth
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import (
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"math"
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"testing"
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)
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func TestPanGainsCenter(t *testing.T) {
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gainL, gainR := PanGains(0.0)
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expected := math.Sqrt2 / 2 // cos(pi/4) = sin(pi/4) = 0.707...
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if math.Abs(gainL-expected) > 1e-9 {
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t.Errorf("PanGains(0.0) gainL = %v, want ~%v", gainL, expected)
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}
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if math.Abs(gainR-expected) > 1e-9 {
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t.Errorf("PanGains(0.0) gainR = %v, want ~%v", gainR, expected)
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}
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}
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func TestPanGainsFullLeft(t *testing.T) {
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gainL, gainR := PanGains(-1.0)
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if math.Abs(gainL-1.0) > 1e-9 {
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t.Errorf("PanGains(-1.0) gainL = %v, want ~1.0", gainL)
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}
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if math.Abs(gainR-0.0) > 1e-9 {
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t.Errorf("PanGains(-1.0) gainR = %v, want ~0.0", gainR)
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}
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}
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func TestPanGainsFullRight(t *testing.T) {
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gainL, gainR := PanGains(1.0)
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if math.Abs(gainL-0.0) > 1e-9 {
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t.Errorf("PanGains(1.0) gainL = %v, want ~0.0", gainL)
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}
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if math.Abs(gainR-1.0) > 1e-9 {
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t.Errorf("PanGains(1.0) gainR = %v, want ~1.0", gainR)
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}
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}
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func TestPanGainsPowerPreserved(t *testing.T) {
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pans := []float64{-1.0, -0.75, -0.5, -0.25, 0.0, 0.25, 0.5, 0.75, 1.0}
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for _, p := range pans {
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gainL, gainR := PanGains(p)
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power := gainL*gainL + gainR*gainR
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if math.Abs(power-1.0) > 1e-9 {
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t.Errorf("PanGains(%v) power = %v, want 1.0 (constant power law)", p, power)
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}
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}
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}
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func TestStereoFramesToInt16Bytes(t *testing.T) {
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frames := [][2]float64{{1.0, -1.0}}
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buf := StereoFramesToInt16Bytes(frames)
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if len(buf) != 4 {
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t.Fatalf("expected 4 bytes, got %d", len(buf))
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}
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// int16(32767) in little-endian = [0xFF, 0x7F]
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// int16(-32767) in little-endian = [0x01, 0x80]
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expectedL := int16(32767)
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expectedR := int16(-32767)
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gotL := int16(uint16(buf[0]) | uint16(buf[1])<<8)
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gotR := int16(uint16(buf[2]) | uint16(buf[3])<<8)
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if gotL != expectedL {
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t.Errorf("left channel = %d, want %d", gotL, expectedL)
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}
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if gotR != expectedR {
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t.Errorf("right channel = %d, want %d", gotR, expectedR)
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}
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}
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func TestStereoFramesToInt16BytesZero(t *testing.T) {
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frames := [][2]float64{{0.0, 0.0}}
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buf := StereoFramesToInt16Bytes(frames)
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if len(buf) != 4 {
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t.Fatalf("expected 4 bytes, got %d", len(buf))
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}
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for i, b := range buf {
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if b != 0 {
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t.Errorf("byte[%d] = %d, want 0", i, b)
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}
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}
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}
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func TestClampPreventsOverflow(t *testing.T) {
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// Values > 1.0 should be clamped to 1.0 before int16 conversion
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frames := [][2]float64{{2.0, -2.0}}
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buf := StereoFramesToInt16Bytes(frames)
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gotL := int16(uint16(buf[0]) | uint16(buf[1])<<8)
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gotR := int16(uint16(buf[2]) | uint16(buf[3])<<8)
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// Should be clamped to max int16 positive / negative
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if gotL != int16(32767) {
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t.Errorf("clamped left = %d, want 32767", gotL)
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}
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if gotR != int16(-32767) {
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t.Errorf("clamped right = %d, want -32767", gotR)
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}
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}
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