ebiten/audio/mp3/decode_notgopherjs.go

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// Copyright 2017 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build !js wasm
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// Package mp3 provides MP3 decoder.
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//
// On desktops and mobiles, a pure Go decoder is used.
// On browsers, a native decoder on the browser is used.
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package mp3
import (
"io"
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"runtime"
"github.com/hajimehoshi/go-mp3"
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"github.com/hajimehoshi/ebiten/audio"
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"github.com/hajimehoshi/ebiten/audio/internal/convert"
)
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// Stream is a decoded stream.
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type Stream struct {
orig *mp3.Decoder
resampling *convert.Resampling
toClose io.Closer
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}
// Read is implementation of io.Reader's Read.
func (s *Stream) Read(buf []byte) (int, error) {
if s.resampling != nil {
return s.resampling.Read(buf)
}
return s.orig.Read(buf)
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}
// Seek is implementation of io.Seeker's Seek.
func (s *Stream) Seek(offset int64, whence int) (int64, error) {
if s.resampling != nil {
return s.resampling.Seek(offset, whence)
}
return s.orig.Seek(offset, whence)
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}
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// Close is implementation of io.Closer's Close.
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func (s *Stream) Close() error {
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runtime.SetFinalizer(s, nil)
return s.toClose.Close()
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}
// Length returns the size of decoded stream in bytes.
func (s *Stream) Length() int64 {
if s.resampling != nil {
return s.resampling.Length()
}
return s.orig.Length()
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}
// Size is deprecated as of 1.6.0-alpha. Use Length instead.
func (s *Stream) Size() int64 {
return s.Length()
}
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// Decode decodes MP3 source and returns a decoded stream.
//
// Decode returns error when decoding fails or IO error happens.
//
// Decode automatically resamples the stream to fit with the audio context if necessary.
//
// Decode takes the ownership of src, and Stream's Close function closes src.
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func Decode(context *audio.Context, src audio.ReadSeekCloser) (*Stream, error) {
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d, err := mp3.NewDecoder(src)
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if err != nil {
return nil, err
}
var r *convert.Resampling
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if d.SampleRate() != context.SampleRate() {
r = convert.NewResampling(d, d.Length(), d.SampleRate(), context.SampleRate())
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}
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s := &Stream{
orig: d,
resampling: r,
toClose: src,
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}
runtime.SetFinalizer(s, (*Stream).Close)
return s, nil
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}