mirror of
https://github.com/hajimehoshi/ebiten.git
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93 lines
2.5 KiB
Go
93 lines
2.5 KiB
Go
// 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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// 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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// On browsers, a native decoder on the browser is used.
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package mp3
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import (
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"io"
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"runtime"
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"github.com/hajimehoshi/go-mp3"
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"github.com/hajimehoshi/ebiten/v2/audio"
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"github.com/hajimehoshi/ebiten/v2/audio/internal/convert"
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)
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// Stream is a decoded stream.
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type Stream struct {
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orig *mp3.Decoder
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resampling *convert.Resampling
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toClose io.Closer
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}
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// Read is implementation of io.Reader's Read.
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func (s *Stream) Read(buf []byte) (int, error) {
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if s.resampling != nil {
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return s.resampling.Read(buf)
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}
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return s.orig.Read(buf)
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}
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// Seek is implementation of io.Seeker's Seek.
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func (s *Stream) Seek(offset int64, whence int) (int64, error) {
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if s.resampling != nil {
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return s.resampling.Seek(offset, whence)
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}
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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)
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return s.toClose.Close()
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}
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// Length returns the size of decoded stream in bytes.
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func (s *Stream) Length() int64 {
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if s.resampling != nil {
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return s.resampling.Length()
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}
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return s.orig.Length()
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}
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// Decode decodes MP3 source and returns a decoded stream.
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//
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// Decode returns error when decoding fails or IO error happens.
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//
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// Decode automatically resamples the stream to fit with the audio context if necessary.
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//
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// 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 {
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return nil, err
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}
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var r *convert.Resampling
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if d.SampleRate() != context.SampleRate() {
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r = convert.NewResampling(d, d.Length(), d.SampleRate(), context.SampleRate())
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}
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s := &Stream{
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orig: d,
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resampling: r,
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toClose: src,
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}
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runtime.SetFinalizer(s, (*Stream).Close)
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return s, nil
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}
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