mirror of
https://github.com/hajimehoshi/ebiten.git
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Hajime Hoshi
parent
7a0e31a23a
commit
a22fdee171
@ -12,8 +12,6 @@
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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 wasm
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// Package mp3 provides MP3 decoder.
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//
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// On desktops and mobiles, a pure Go decoder is used.
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@ -1,245 +0,0 @@
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// Copyright 2017 The Ebiten 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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// +build js
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// +build !wasm
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package mp3
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import (
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"math"
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"syscall/js"
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"time"
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"github.com/hajimehoshi/ebiten/v2/audio"
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)
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// TODO: This just uses decodeAudioData, that can treat audio files other than MP3.
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type Stream struct {
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leftData []float32
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rightData []float32
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posInBytes int
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}
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var (
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errTryAgain = errors.New("mp3: try again")
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errTimeout = errors.New("mp3: timeout")
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)
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func (s *Stream) Read(b []byte) (int, error) {
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l := len(s.leftData)*4 - s.posInBytes
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if l > len(b) {
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l = len(b)
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}
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l = l / 4 * 4
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const max = 1<<15 - 1
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for i := 0; i < l/4; i++ {
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il := int32(s.leftData[s.posInBytes/4+i] * max)
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if il > max {
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il = max
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}
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if il < -max {
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il = -max
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}
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ir := int32(s.rightData[s.posInBytes/4+i] * max)
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if ir > max {
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ir = max
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}
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if ir < -max {
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ir = -max
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}
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b[4*i] = byte(il)
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b[4*i+1] = byte(il >> 8)
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b[4*i+2] = byte(ir)
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b[4*i+3] = byte(ir >> 8)
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}
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s.posInBytes += l
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if s.posInBytes == len(s.leftData)*4 {
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return l, io.EOF
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}
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return l, nil
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}
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func (s *Stream) Seek(offset int64, whence int) (int64, error) {
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next := int64(0)
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switch whence {
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case io.SeekStart:
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next = offset
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case io.SeekCurrent:
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next = int64(s.posInBytes) + offset
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case io.SeekEnd:
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next = s.Length() + offset
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}
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s.posInBytes = int(next)
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return next, nil
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}
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func (s *Stream) Close() error {
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return nil
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}
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func (s *Stream) Length() int64 {
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return int64(len(s.leftData) * 4)
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}
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// seekNextFrame seeks the next frame and returns the new buffer with the new position.
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// seekNextFrame also returns true when seeking is successful, or false otherwise.
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//
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// Seeking is necessary when decoding fails. Safari's MP3 decoder can't treat IDs well (#438).
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func seekNextFrame(buf []byte) ([]byte, bool) {
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// TODO: Need to skip tags explicitly? (hajimehoshi/go-mp3#9)
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if len(buf) < 1 {
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return nil, false
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}
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buf = buf[1:]
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for {
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if buf[0] == 0xff && buf[1]&0xfe == 0xfe {
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break
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}
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buf = buf[1:]
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if len(buf) < 2 {
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return nil, false
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}
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}
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return buf, true
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}
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func Decode(context *audio.Context, src audio.ReadSeekCloser) (*Stream, error) {
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b, err := ioutil.ReadAll(src)
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if err != nil {
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return nil, err
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}
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if err := src.Close(); err != nil {
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return nil, err
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}
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var s *Stream
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try := 0
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for {
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s, err = decode(context, b, try)
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switch err {
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case errTryAgain:
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buf, ok := seekNextFrame(b)
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if !ok {
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return nil, fmt.Errorf("mp3: Decode failed: invalid format?")
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}
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b = buf
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continue
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case errTimeout:
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try++
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continue
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default:
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if err != nil {
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return nil, err
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}
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}
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break
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}
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return s, nil
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}
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var offlineAudioContextClass = js.Null()
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func init() {
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if klass := js.Global().Get("OfflineAudioContext"); klass != js.Undefined() {
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offlineAudioContextClass = klass
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return
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}
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if klass := js.Global().Get("webkitOfflineAudioContext"); klass != js.Undefined() {
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offlineAudioContextClass = klass
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return
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}
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}
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func float32ArrayToSlice(arr js.Value) []float32 {
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f := make([]float32, arr.Length())
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a := js.TypedArrayOf(f)
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a.Call("set", arr)
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a.Release()
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return f
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}
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func decode(context *audio.Context, buf []byte, try int) (*Stream, error) {
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if offlineAudioContextClass == js.Null() {
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return nil, errors.New("mp3: OfflineAudioContext is not available")
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}
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s := &Stream{}
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ch := make(chan error)
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// TODO: webkitOfflineAudioContext's constructor might causes 'Syntax' error
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// when the sample rate is not so usual like 22050 on Safari.
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// Should this be handled before calling this?
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// TODO: 1 is a correct second argument?
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oc := offlineAudioContextClass.New(2, 1, context.SampleRate())
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u8 := js.TypedArrayOf(buf)
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defer u8.Release()
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a := u8.Get("buffer").Call("slice", u8.Get("byteOffset"), u8.Get("byteOffset").Int()+u8.Get("byteLength").Int())
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succeeded := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
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buf := args[0]
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s.leftData = float32ArrayToSlice(buf.Call("getChannelData", 0))
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switch n := buf.Get("numberOfChannels").Int(); n {
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case 1:
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s.rightData = s.leftData
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close(ch)
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case 2:
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s.rightData = float32ArrayToSlice(buf.Call("getChannelData", 1))
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close(ch)
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default:
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ch <- fmt.Errorf("mp3: number of channels must be 1 or 2 but %d", n)
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}
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return nil
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})
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defer succeeded.Release()
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failed := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
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err := args[0]
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if err != js.Null() || err != js.Undefined() {
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ch <- fmt.Errorf("mp3: decodeAudioData failed: %v", err)
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} else {
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// On Safari, error value might be null and it is needed to retry decoding
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// from the next frame (#438).
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ch <- errTryAgain
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}
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return nil
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})
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defer failed.Release()
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oc.Call("decodeAudioData", a, succeeded, failed)
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timeout := time.Duration(math.Pow(2, float64(try))) * time.Second
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t := time.NewTimer(timeout)
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defer t.Stop()
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select {
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case err := <-ch:
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if err != nil {
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return nil, err
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}
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case <-t.C:
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// Sometimes decode fails without calling the callbacks (#464).
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// Let's just try again in this case.
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return nil, errTimeout
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}
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return s, nil
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}
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