ebiten/exp/audio/audio_js.go
2016-04-03 06:36:04 +09:00

133 lines
3.3 KiB
Go

// Copyright 2015 Hajime Hoshi
//
// 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.
// +build js
package audio
import (
"errors"
"io"
"runtime"
"github.com/gopherjs/gopherjs/js"
"github.com/hajimehoshi/ebiten"
)
type player struct {
src io.Reader
sampleRate int
positionInSamples int64
context *js.Object
bufferSource *js.Object
}
func startPlaying(src io.Reader, sampleRate int) error {
// Do nothing in node.js.
if js.Global.Get("require") != js.Undefined {
return nil
}
class := js.Global.Get("AudioContext")
if class == js.Undefined {
class = js.Global.Get("webkitAudioContext")
}
if class == js.Undefined {
return errors.New("audio: audio couldn't be initialized")
}
p := &player{
src: src,
sampleRate: sampleRate,
bufferSource: nil,
context: class.New(),
}
p.positionInSamples = int64(p.context.Get("currentTime").Float() * float64(p.sampleRate))
return p.start()
}
func toLR(data []byte) ([]int16, []int16) {
l := make([]int16, len(data)/4)
r := make([]int16, len(data)/4)
for i := 0; i < len(data)/4; i++ {
l[i] = int16(data[4*i]) | int16(data[4*i+1])<<8
r[i] = int16(data[4*i+2]) | int16(data[4*i+3])<<8
}
return l, r
}
func max64(a, b int64) int64 {
if a > b {
return a
}
return b
}
func (p *player) proceed() error {
bufferSize := p.sampleRate * bytesPerSample * channelNum / ebiten.FPS
c := int64(p.context.Get("currentTime").Float() * float64(p.sampleRate))
if p.positionInSamples < c {
p.positionInSamples = c
}
b := make([]byte, bufferSize)
n, err := p.src.Read(b)
if 0 < n {
buf := p.context.Call("createBuffer", channelNum, n/bytesPerSample/channelNum, p.sampleRate)
l := buf.Call("getChannelData", 0)
r := buf.Call("getChannelData", 1)
il, ir := toLR(b[:n])
const max = 1 << 15
for i := 0; i < len(il); i++ {
l.SetIndex(i, float64(il[i])/max)
r.SetIndex(i, float64(ir[i])/max)
}
p.bufferSource = p.context.Call("createBufferSource")
p.bufferSource.Set("buffer", buf)
p.bufferSource.Call("connect", p.context.Get("destination"))
p.bufferSource.Call("start", float64(p.positionInSamples)/float64(p.sampleRate))
// Call 'stop' or we'll get noisy sound especially on Chrome.
p.bufferSource.Call("stop", float64(p.positionInSamples+int64(len(il)))/float64(p.sampleRate))
p.positionInSamples += int64(len(il))
}
return err
}
func (p *player) start() error {
// TODO: What if play is already called?
go func() {
defer p.close()
for {
err := p.proceed()
if err == io.EOF {
break
}
if err != nil {
// TODO: Record the last error
panic(err)
}
runtime.Gosched()
}
}()
return nil
}
func (p *player) close() error {
if p.bufferSource == nil {
return nil
}
p.bufferSource.Call("stop")
p.bufferSource.Call("disconnect")
p.bufferSource = nil
return nil
}