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examples/piano: use NewPlayerF32FromBytes

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Updates #2160
This commit is contained in:
Hajime Hoshi 2024-07-22 23:26:02 +09:00
parent a12e32faf9
commit ce6931f81c
1 changed files with 25 additions and 19 deletions
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44
examples/piano/main.go
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@ -54,30 +54,36 @@ const (
) )
// pianoAt returns an i-th sample of piano with the given frequency. // pianoAt returns an i-th sample of piano with the given frequency.
func pianoAt(i int, freq float64) float64 { func pianoAt(i int, freq float32) float32 {
// Create piano-like waves with multiple sin waves. // Create piano-like waves with multiple sin waves.
amp := []float64{1.0, 0.8, 0.6, 0.4, 0.2} amp := []float32{1.0, 0.8, 0.6, 0.4, 0.2}
x := []float64{4.0, 2.0, 1.0, 0.5, 0.25} x := []float32{4.0, 2.0, 1.0, 0.5, 0.25}
v := 0.0 var v float32
for j := 0; j < len(amp); j++ { for j := 0; j < len(amp); j++ {
// Decay // Decay
a := amp[j] * math.Exp(-5*float64(i)*freq/baseFreq/(x[j]*sampleRate)) a := amp[j] * float32(math.Exp(float64(-5*float32(i)*freq/baseFreq/(x[j]*sampleRate))))
v += a * math.Sin(2.0*math.Pi*float64(i)*freq*float64(j+1)/sampleRate) v += a * float32(math.Sin(2.0*math.Pi*float64(i)*float64(freq)*float64(j+1)/sampleRate))
} }
return v / 5.0 return v / 5.0
} }
// toBytes returns the 2ch little endian 16bit byte sequence with the given left/right sequence. // toBytes returns the 2ch little endian 16bit byte sequence with the given left/right sequence.
func toBytes(l, r []int16) []byte { func toBytes(l, r []float32) []byte {
if len(l) != len(r) { if len(l) != len(r) {
panic("len(l) must equal to len(r)") panic("len(l) must equal to len(r)")
} }
b := make([]byte, len(l)*4) b := make([]byte, len(l)*8)
for i := range l { for i := range l {
b[4*i] = byte(l[i]) lv := math.Float32bits(l[i])
b[4*i+1] = byte(l[i] >> 8) rv := math.Float32bits(r[i])
b[4*i+2] = byte(r[i]) b[8*i] = byte(lv)
b[4*i+3] = byte(r[i] >> 8) b[8*i+1] = byte(lv >> 8)
b[8*i+2] = byte(lv >> 16)
b[8*i+3] = byte(lv >> 24)
b[8*i+4] = byte(rv)
b[8*i+5] = byte(rv >> 8)
b[8*i+6] = byte(rv >> 16)
b[8*i+7] = byte(rv >> 24)
} }
return b return b
} }
@ -96,9 +102,9 @@ func init() {
// Create a reference data and use this for other frequency. // Create a reference data and use this for other frequency.
const refFreq = 110 const refFreq = 110
length := 4 * sampleRate * baseFreq / refFreq length := 4 * sampleRate * baseFreq / refFreq
refData := make([]int16, length) refData := make([]float32, length)
for i := 0; i < length; i++ { for i := 0; i < length; i++ {
refData[i] = int16(pianoAt(i, refFreq) * math.MaxInt16) refData[i] = pianoAt(i, refFreq)
} }
for i := range keys { for i := range keys {
@ -106,8 +112,8 @@ func init() {
// Calculate the wave data for the freq. // Calculate the wave data for the freq.
length := 4 * sampleRate * baseFreq / int(freq) length := 4 * sampleRate * baseFreq / int(freq)
l := make([]int16, length) l := make([]float32, length)
r := make([]int16, length) r := make([]float32, length)
for i := 0; i < length; i++ { for i := 0; i < length; i++ {
idx := int(float64(i) * freq / refFreq) idx := int(float64(i) * freq / refFreq)
if len(refData) <= idx { if len(refData) <= idx {
@ -214,16 +220,16 @@ func (g *Game) Update() error {
if !inpututil.IsKeyJustPressed(key) { if !inpututil.IsKeyJustPressed(key) {
continue continue
} }
g.playNote(baseFreq * math.Exp2(float64(i-1)/12.0)) g.playNote(baseFreq * float32(math.Exp2(float64(i-1)/12.0)))
} }
} }
return nil return nil
} }
// playNote plays piano sound with the given frequency. // playNote plays piano sound with the given frequency.
func (g *Game) playNote(freq float64) { func (g *Game) playNote(freq float32) {
f := int(freq) f := int(freq)
p := g.audioContext.NewPlayerFromBytes(pianoNoteSamples[f]) p := g.audioContext.NewPlayerF32FromBytes(pianoNoteSamples[f])
p.Play() p.Play()
} }