ebiten/examples/realtimepcm/main.go
2024-07-23 01:06:44 +09:00

146 lines
3.2 KiB
Go

// Copyright 2022 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"log"
"math"
"sync"
"time"
"github.com/hajimehoshi/ebiten/v2"
"github.com/hajimehoshi/ebiten/v2/audio"
"github.com/hajimehoshi/ebiten/v2/ebitenutil"
)
const (
screenWidth = 640
screenHeight = 480
sampleRate = 48000
)
type Game struct {
audioContext *audio.Context
player *audio.Player
sineWave *SineWave
}
type SineWave struct {
frequency int
minFrequency int
maxFrequency int
// pos is the position in the wave length in the range of [0, 1).
pos float64
m sync.Mutex
}
func NewSineWave() *SineWave {
return &SineWave{
frequency: 440,
minFrequency: 440,
maxFrequency: 880,
}
}
func (s *SineWave) Update(raisePitch bool) {
s.m.Lock()
defer s.m.Unlock()
if raisePitch {
if s.frequency < s.maxFrequency {
s.frequency += 10
}
} else {
if s.frequency > s.minFrequency {
s.frequency -= 10
}
}
}
func (s *SineWave) Read(buf []byte) (int, error) {
s.m.Lock()
defer s.m.Unlock()
const bytesPerSample = 8
n := len(buf) / bytesPerSample * bytesPerSample
buf = buf[:n]
length := sampleRate / float64(s.frequency)
p := float64(length * s.pos)
for i := 0; i < n/bytesPerSample; i++ {
v := math.Float32bits(float32(math.Sin(2 * math.Pi * p / length)))
buf[8*i] = byte(v)
buf[8*i+1] = byte(v >> 8)
buf[8*i+2] = byte(v >> 16)
buf[8*i+3] = byte(v >> 24)
buf[8*i+4] = byte(v)
buf[8*i+5] = byte(v >> 8)
buf[8*i+6] = byte(v >> 16)
buf[8*i+7] = byte(v >> 24)
p++
}
_, s.pos = math.Modf(p / length)
return n, nil
}
func NewGame() *Game {
return &Game{
audioContext: audio.NewContext(sampleRate),
}
}
func (g *Game) Update() error {
if g.audioContext == nil {
g.audioContext = audio.NewContext(sampleRate)
}
if g.player == nil {
g.sineWave = NewSineWave()
p, err := g.audioContext.NewPlayerF32(g.sineWave)
if err != nil {
return err
}
g.player = p
g.player.Play()
// Adjust the buffer size to reflect the audio source changes in real time.
// Note that Ebitengine doesn't guarantee the audio quality when the buffer size is modified.
// 1/20[s] should work in most cases, but this might cause glitches in some environments.
g.player.SetBufferSize(time.Second / 20)
}
g.sineWave.Update(ebiten.IsKeyPressed(ebiten.KeyA))
return nil
}
func (g *Game) Draw(screen *ebiten.Image) {
ebitenutil.DebugPrint(screen, "This is an example of a real time PCM.\nPress and hold the A key.")
}
func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
return screenWidth, screenHeight
}
func main() {
ebiten.SetWindowSize(screenWidth, screenHeight)
ebiten.SetWindowTitle("Real Time PCM (Ebitengine Demo)")
if err := ebiten.RunGame(NewGame()); err != nil {
log.Fatal(err)
}
}