mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-12-26 11:48:55 +01:00
128 lines
3.2 KiB
Go
128 lines
3.2 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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"time"
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"github.com/gopherjs/gopherjs/js"
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"github.com/hajimehoshi/ebiten"
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)
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type player struct {
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src io.Reader
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sampleRate int
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positionInSamples int64
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context *js.Object
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bufferSource *js.Object
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}
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func startPlaying(src io.Reader, sampleRate int) error {
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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 nil
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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 errors.New("audio: audio couldn't be initialized")
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}
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p := &player{
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src: src,
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sampleRate: sampleRate,
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bufferSource: nil,
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context: class.New(),
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}
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p.positionInSamples = int64(p.context.Get("currentTime").Float() * float64(p.sampleRate))
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go func() {
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defer p.close()
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for {
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err := p.proceed()
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if err == io.EOF {
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break
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}
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if err != nil {
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// TODO: Record the last error
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panic(err)
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}
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time.Sleep(1 * time.Millisecond)
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}
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}()
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return nil
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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 max64(a, b int64) int64 {
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if a > b {
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return a
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}
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return b
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}
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func (p *player) proceed() error {
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bufferSize := p.sampleRate * bytesPerSample * channelNum / ebiten.FPS
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c := int64(p.context.Get("currentTime").Float() * float64(p.sampleRate))
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if p.positionInSamples < c {
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p.positionInSamples = c
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}
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b := make([]byte, bufferSize)
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n, err := p.src.Read(b)
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if 0 < n {
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buf := p.context.Call("createBuffer", channelNum, n/bytesPerSample/channelNum, p.sampleRate)
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l := buf.Call("getChannelData", 0)
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r := buf.Call("getChannelData", 1)
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il, ir := toLR(b[:n])
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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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p.bufferSource = p.context.Call("createBufferSource")
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p.bufferSource.Set("buffer", buf)
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p.bufferSource.Call("connect", p.context.Get("destination"))
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p.bufferSource.Call("start", float64(p.positionInSamples)/float64(p.sampleRate))
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// Call 'stop' or we'll get noisy sound especially on Chrome.
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p.bufferSource.Call("stop", float64(p.positionInSamples+int64(len(il)))/float64(p.sampleRate))
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p.positionInSamples += int64(len(il))
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}
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return err
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}
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func (p *player) close() error {
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if p.bufferSource == nil {
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return nil
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}
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p.bufferSource.Call("stop")
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p.bufferSource.Call("disconnect")
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p.bufferSource = nil
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return nil
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}
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