142 lines
3.9 KiB
Go
142 lines
3.9 KiB
Go
// Copyright 2021 The Oto 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 oto
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import (
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"errors"
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"runtime"
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"syscall/js"
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"unsafe"
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"github.com/ebitengine/oto/v3/internal/mux"
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)
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type context struct {
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audioContext js.Value
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scriptProcessor js.Value
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scriptProcessorCallback js.Func
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ready bool
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callbacks map[string]js.Func
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mux *mux.Mux
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}
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func newContext(sampleRate int, channelCount int, format mux.Format, bufferSizeInBytes int) (*context, chan struct{}, error) {
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ready := make(chan struct{})
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class := js.Global().Get("AudioContext")
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if !class.Truthy() {
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class = js.Global().Get("webkitAudioContext")
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}
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if !class.Truthy() {
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return nil, nil, errors.New("oto: AudioContext or webkitAudioContext was not found")
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}
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options := js.Global().Get("Object").New()
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options.Set("sampleRate", sampleRate)
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d := &context{
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audioContext: class.New(options),
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mux: mux.New(sampleRate, channelCount, format),
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}
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if bufferSizeInBytes == 0 {
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// 4096 was not great at least on Safari 15.
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bufferSizeInBytes = 8192 * channelCount
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}
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buf32 := make([]float32, bufferSizeInBytes/4)
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chBuf32 := make([][]float32, channelCount)
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for i := range chBuf32 {
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chBuf32[i] = make([]float32, len(buf32)/channelCount)
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}
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// TODO: Use AudioWorklet if available.
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sp := d.audioContext.Call("createScriptProcessor", bufferSizeInBytes/4/channelCount, 0, channelCount)
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f := js.FuncOf(func(this js.Value, arguments []js.Value) any {
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d.mux.ReadFloat32s(buf32)
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for i := 0; i < channelCount; i++ {
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for j := range chBuf32[i] {
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chBuf32[i][j] = buf32[j*channelCount+i]
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}
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}
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buf := arguments[0].Get("outputBuffer")
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if buf.Get("copyToChannel").Truthy() {
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for i := 0; i < channelCount; i++ {
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buf.Call("copyToChannel", float32SliceToTypedArray(chBuf32[i]), i, 0)
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}
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} else {
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// copyToChannel is not defined on Safari 11.
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for i := 0; i < channelCount; i++ {
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buf.Call("getChannelData", i).Call("set", float32SliceToTypedArray(chBuf32[i]))
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}
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}
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return nil
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})
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sp.Call("addEventListener", "audioprocess", f)
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d.scriptProcessor = sp
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d.scriptProcessorCallback = f
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sp.Call("connect", d.audioContext.Get("destination"))
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setCallback := func(event string) js.Func {
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var f js.Func
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f = js.FuncOf(func(this js.Value, arguments []js.Value) any {
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if !d.ready {
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d.audioContext.Call("resume")
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d.ready = true
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close(ready)
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}
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js.Global().Get("document").Call("removeEventListener", event, f)
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return nil
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})
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js.Global().Get("document").Call("addEventListener", event, f)
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d.callbacks[event] = f
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return f
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}
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// Browsers require user interaction to start the audio.
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// https://developers.google.com/web/updates/2017/09/autoplay-policy-changes#webaudio
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d.callbacks = map[string]js.Func{}
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setCallback("touchend")
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setCallback("keyup")
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setCallback("mouseup")
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return d, ready, nil
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}
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func (c *context) Suspend() error {
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c.audioContext.Call("suspend")
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return nil
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}
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func (c *context) Resume() error {
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c.audioContext.Call("resume")
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return nil
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}
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func (c *context) Err() error {
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return nil
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}
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func float32SliceToTypedArray(s []float32) js.Value {
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bs := unsafe.Slice((*byte)(unsafe.Pointer(&s[0])), len(s)*4)
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a := js.Global().Get("Uint8Array").New(len(bs))
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js.CopyBytesToJS(a, bs)
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runtime.KeepAlive(s)
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buf := a.Get("buffer")
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return js.Global().Get("Float32Array").New(buf, a.Get("byteOffset"), a.Get("byteLength").Int()/4)
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}
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