mirror of
https://github.com/hajimehoshi/ebiten.git
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f0ef1ecad0
This change adds these APIs * (*audio.Context).NewPlayerF32 * (*audio.Context).NewPlayerF32FromBytes * audio.NewInfiniteLoopF32 * audio.NewInfiniteLoopWithIntroF32 * audio.ResampleF32 * mp3.DecodeF32 * vorbis.DecodeF32 * wav.DecodeF32 Closes #2160
212 lines
5.8 KiB
Go
212 lines
5.8 KiB
Go
// Copyright 2020 The Ebiten Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package main
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import (
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"bytes"
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"fmt"
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"image"
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_ "image/png"
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"io"
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"log"
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"math"
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"time"
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"github.com/hajimehoshi/ebiten/v2"
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"github.com/hajimehoshi/ebiten/v2/audio"
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"github.com/hajimehoshi/ebiten/v2/audio/vorbis"
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"github.com/hajimehoshi/ebiten/v2/ebitenutil"
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raudio "github.com/hajimehoshi/ebiten/v2/examples/resources/audio"
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"github.com/hajimehoshi/ebiten/v2/examples/resources/images"
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)
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const (
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screenWidth = 640
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screenHeight = 480
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sampleRate = 48000
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)
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var ebitenImage *ebiten.Image
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type Game struct {
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player *audio.Player
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panstream *StereoPanStream
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// panning goes from -1 to 1
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// -1: 100% left channel, 0% right channel
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// 0: 100% both channels
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// 1: 0% left channel, 100% right channel
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panning float64
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count int
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xpos float64
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audioContext *audio.Context
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}
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func (g *Game) initAudioIfNeeded() {
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if g.player != nil {
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return
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}
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if g.audioContext == nil {
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g.audioContext = audio.NewContext(sampleRate)
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}
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// Decode an Ogg file.
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// oggS is a decoded io.ReadCloser and io.Seeker.
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oggS, err := vorbis.DecodeF32(bytes.NewReader(raudio.Ragtime_ogg))
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if err != nil {
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log.Fatal(err)
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}
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// Wrap the raw audio with the StereoPanStream
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g.panstream = NewStereoPanStream(audio.NewInfiniteLoop(oggS, oggS.Length()))
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g.panstream.SetPan(g.panning)
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g.player, err = g.audioContext.NewPlayerF32(g.panstream)
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if err != nil {
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log.Fatal(err)
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}
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// Play the infinite-length stream. This never ends.
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g.player.Play()
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}
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// time is within the 0 ... 1 range
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func lerp(a, b, t float64) float64 {
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return a*(1-t) + b*t
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}
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func (g *Game) Update() error {
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g.count++
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r := float64(g.count) * ((1.0 / 60.0) * 2 * math.Pi) * 0.1 // full cycle every 10 seconds
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g.xpos = (float64(screenWidth) / 2) + math.Cos(r)*(float64(screenWidth)/2)
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g.panning = lerp(-1, 1, g.xpos/float64(screenWidth))
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// Initialize the audio after the panning is determined.
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g.initAudioIfNeeded()
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g.panstream.SetPan(g.panning)
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return nil
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}
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func (g *Game) Draw(screen *ebiten.Image) {
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pos := g.player.Position()
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msg := fmt.Sprintf(`TPS: %0.2f
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This is an example using
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stereo audio panning.
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Current: %0.2f[s]
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Panning: %.2f`, ebiten.ActualTPS(), float64(pos)/float64(time.Second), g.panning)
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ebitenutil.DebugPrint(screen, msg)
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// draw image to show where the sound is at related to the screen
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op := &ebiten.DrawImageOptions{}
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op.GeoM.Translate(g.xpos-float64(ebitenImage.Bounds().Dx()/2), screenHeight/2)
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screen.DrawImage(ebitenImage, op)
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}
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func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
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return screenWidth, screenHeight
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}
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func main() {
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// Decode an image from the image file's byte slice.
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img, _, err := image.Decode(bytes.NewReader(images.Ebiten_png))
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if err != nil {
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log.Fatal(err)
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}
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ebitenImage = ebiten.NewImageFromImage(img)
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ebiten.SetWindowSize(screenWidth, screenHeight)
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ebiten.SetWindowTitle("Audio Panning Loop (Ebitengine Demo)")
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g := &Game{}
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if err := ebiten.RunGame(g); err != nil {
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log.Fatal(err)
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}
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}
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// StereoPanStream is an audio buffer that changes the stereo channel's signal
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// based on the Panning.
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type StereoPanStream struct {
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io.ReadSeeker
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pan float64 // -1: left; 0: center; 1: right
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buf []byte
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}
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func (s *StereoPanStream) Read(p []byte) (int, error) {
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// If the stream has a buffer that was read in the previous time, use this first.
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var bufN int
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if len(s.buf) > 0 {
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bufN = copy(p, s.buf)
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s.buf = s.buf[bufN:]
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}
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readN, err := s.ReadSeeker.Read(p[bufN:])
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if err != nil && err != io.EOF {
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return 0, err
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}
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// Align the buffer size in multiples of 4. The extra part is pushed to the buffer for the
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// next time.
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totalN := bufN + readN
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extra := totalN - totalN/8*8
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s.buf = append(s.buf, p[totalN-extra:totalN]...)
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alignedN := totalN - extra
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// This implementation uses a linear scale, ranging from -1 to 1, for stereo or mono sounds.
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// If pan = 0.0, the balance for the sound in each speaker is at 100% left and 100% right.
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// When pan is -1.0, only the left channel of the stereo sound is audible, when pan is 1.0,
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// only the right channel of the stereo sound is audible.
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// https://docs.unity3d.com/ScriptReference/AudioSource-panStereo.html
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ls := float32(math.Min(s.pan*-1+1, 1))
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rs := float32(math.Min(s.pan+1, 1))
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for i := 0; i < alignedN; i += 8 {
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lc := math.Float32frombits(uint32(p[i])|(uint32(p[i+1])<<8)|(uint32(p[i+2])<<16)|(uint32(p[i+3])<<24)) * ls
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rc := math.Float32frombits(uint32(p[i+4])|(uint32(p[i+5])<<8)|(uint32(p[i+6])<<16)|(uint32(p[i+7])<<24)) * rs
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lcBits := math.Float32bits(lc)
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rcBits := math.Float32bits(rc)
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p[i] = byte(lcBits)
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p[i+1] = byte(lcBits >> 8)
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p[i+2] = byte(lcBits >> 16)
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p[i+3] = byte(lcBits >> 24)
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p[i+4] = byte(rcBits)
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p[i+5] = byte(rcBits >> 8)
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p[i+6] = byte(rcBits >> 16)
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p[i+7] = byte(rcBits >> 24)
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}
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return alignedN, err
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}
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func (s *StereoPanStream) SetPan(pan float64) {
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s.pan = math.Min(math.Max(-1, pan), 1)
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}
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func (s *StereoPanStream) Pan() float64 {
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return s.pan
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}
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// NewStereoPanStream returns a new StereoPanStream with a buffered src.
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//
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// The src's format must be linear PCM (16bits little endian, 2 channel stereo)
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// without a header (e.g. RIFF header). The sample rate must be same as that
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// of the audio context.
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func NewStereoPanStream(src io.ReadSeeker) *StereoPanStream {
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return &StereoPanStream{
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ReadSeeker: src,
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}
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}
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