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audio: Bug fix: Reduce noise by using long buffers (#205)

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This commit is contained in:
Hajime Hoshi 2016-04-21 02:48:43 +09:00
parent 9a18ffe563
commit 5d5f27bcbf
1 changed files with 27 additions and 16 deletions
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43
audio/internal/driver/driver_js.go
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@ -27,6 +27,7 @@ type Player struct {
channelNum int
bytesPerSample int
positionInSamples int64
bufferedData []byte
context *js.Object
bufferSource *js.Object
}
@ -43,6 +44,7 @@ func NewPlayer(sampleRate, channelNum, bytesPerSample int) (*Player, error) {
sampleRate: sampleRate,
channelNum: channelNum,
bytesPerSample: bytesPerSample,
bufferedData: []byte{},
bufferSource: nil,
context: class.New(),
}
@ -61,27 +63,36 @@ func toLR(data []byte) ([]int16, []int16) {
}
func (p *Player) Proceed(data []byte) error {
p.bufferedData = append(p.bufferedData, data...)
c := int64(p.context.Get("currentTime").Float() * float64(p.sampleRate))
if p.positionInSamples < c {
p.positionInSamples = c
}
n := len(data)
buf := p.context.Call("createBuffer", p.channelNum, n/p.bytesPerSample/p.channelNum, p.sampleRate)
l := buf.Call("getChannelData", 0)
r := buf.Call("getChannelData", 1)
il, ir := toLR(data)
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)
// Looks like low sample rate (e.g. 22050) requires a quite long buffer (#205).
// 4096 is not perfect but it reduce noise to some extent.
const dataSize = 4096
for dataSize <= len(p.bufferedData) {
data := p.bufferedData[:dataSize]
size := len(data) / p.bytesPerSample / p.channelNum
// TODO: size must be const or you'll get noise (e.g. sample rate is 22050)
buf := p.context.Call("createBuffer", p.channelNum, size, p.sampleRate)
l := buf.Call("getChannelData", 0)
r := buf.Call("getChannelData", 1)
il, ir := toLR(data)
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))
p.bufferedData = p.bufferedData[dataSize:]
}
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 nil
}