resampling.go

func (p *player) resample() {
        inL, inR := toLR(p.buf)
        if len(inL) != len(inR) {
                panic("oto: len(inL) must == len(inR)")
        }

        s := p.context.Get("sampleRate").Int()
        if p.sampleRate == s {
                p.buf = nil
                p.bufL = append(p.bufL, inL...)
                p.bufR = append(p.bufR, inR...)
                return
        }

        outLen := len(inL) * s / p.sampleRate
        if outLen == 0 {
                return
        }

        ctx := offlineAudioContextClass.New(p.channelNum, outLen, s)
        ctx.Set("oncomplete", func(e *js.Object) {
                buf := e.Get("renderedBuffer")
                outL := buf.Call("getChannelData", 0).Interface().([]float32)
                outR := buf.Call("getChannelData", 1).Interface().([]float32)
                p.bufL = append(p.bufL, outL...)
                p.bufR = append(p.bufR, outR...)
        })

        buf := ctx.Call("createBuffer", p.channelNum, len(inL), p.sampleRate)
        buf.Call("copyToChannel", inL, 0, 0)
        buf.Call("copyToChannel", inR, 1, 0)
        src := ctx.Call("createBufferSource")
        src.Set("buffer", buf)
        src.Call("connect", ctx.Get("destination"))
        src.Call("start", 0)
}