mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-09-20 13:22:19 +02:00
103 lines
2.4 KiB
Go
103 lines
2.4 KiB
Go
// Copyright 2015 Hajime Hoshi
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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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// +build js
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package audio
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import (
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"errors"
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"io"
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"io/ioutil"
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"github.com/gopherjs/gopherjs/js"
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)
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var context *js.Object
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type audioProcessor struct {
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src io.ReadSeeker
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sampleRate int
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position float64
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}
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func toLR(data []byte) ([]int16, []int16) {
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l := make([]int16, len(data)/4)
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r := make([]int16, len(data)/4)
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for i := 0; i < len(data)/4; i++ {
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l[i] = int16(data[4*i]) | int16(data[4*i+1])<<8
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r[i] = int16(data[4*i+2]) | int16(data[4*i+3])<<8
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}
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return l, r
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}
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func (a *audioProcessor) play() error {
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// TODO: Reading all data at once is temporary implemntation. Treat this as stream.
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buf, err := ioutil.ReadAll(a.src)
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if err != nil {
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return err
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}
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if len(buf) == 0 {
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return nil
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}
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const channelNum = 2
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const bytesPerSample = channelNum * 16 / 8
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b := context.Call("createBuffer", channelNum, len(buf)/bytesPerSample, a.sampleRate)
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l := b.Call("getChannelData", 0)
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r := b.Call("getChannelData", 1)
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il, ir := toLR(buf)
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const max = 1 << 15
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for i := 0; i < len(il); i++ {
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l.SetIndex(i, float64(il[i])/max)
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r.SetIndex(i, float64(ir[i])/max)
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}
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s := context.Call("createBufferSource")
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s.Set("buffer", b)
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s.Call("connect", context.Get("destination"))
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s.Call("start", a.position)
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a.position += b.Get("duration").Float()
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return nil
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}
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func play(src io.ReadSeeker, sampleRate int) error {
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if context == nil {
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if !initialize() {
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return errors.New("audio couldn't be initialized")
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}
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}
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a := &audioProcessor{
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src: src,
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sampleRate: sampleRate,
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position: context.Get("currentTime").Float(),
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}
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return a.play()
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}
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func initialize() bool {
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// Do nothing in node.js.
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if js.Global.Get("require") != js.Undefined {
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return false
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}
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class := js.Global.Get("AudioContext")
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if class == js.Undefined {
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class = js.Global.Get("webkitAudioContext")
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}
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if class == js.Undefined {
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return false
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}
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context = class.New()
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return true
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}
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