audio/mp3: Add JavaScript version

audio/mp3/decode.go

@@ -1,66 +0,0 @@
-// 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.
-
-// Package mp3 provides MP3 decoder.
-//
-// This package is very experimental.
-package mp3
-
-import (
-	"github.com/hajimehoshi/ebiten/audio"
-	"github.com/hajimehoshi/ebiten/audio/internal/convert"
-)
-
-type Stream struct {
-	inner audio.ReadSeekCloser
-	size  int64
-}
-
-// Read is implementation of io.Reader's Read.
-func (s *Stream) Read(buf []byte) (int, error) {
-	return s.inner.Read(buf)
-}
-
-// Seek is implementation of io.Seeker's Seek.
-func (s *Stream) Seek(offset int64, whence int) (int64, error) {
-	return s.inner.Seek(offset, whence)
-}
-
-// Read is implementation of io.Closer's Close.
-func (s *Stream) Close() error {
-	return s.inner.Close()
-}
-
-// Size returns the size of decoded stream in bytes.
-func (s *Stream) Size() int64 {
-	return s.size
-}
-
-func Decode(context *audio.Context, src audio.ReadSeekCloser) (*Stream, error) {
-	d, err := decode(src)
-	if err != nil {
-		return nil, err
-	}
-	// TODO: Resampling
-	var s audio.ReadSeekCloser = convert.NewSeeker(d)
-	size := d.Length()
-	if d.SampleRate() != context.SampleRate() {
-		s = convert.NewResampling(s, d.Length(), d.SampleRate(), context.SampleRate())
-		size = size * int64(context.SampleRate()) / int64(d.SampleRate())
-	}
-	return &Stream{
-		inner: s,
-		size:  size,
-	}, nil
-}

audio/mp3/decode_js.go

@@ -0,0 +1,106 @@
+// 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
+
+package mp3
+
+import (
+	"errors"
+	"io"
+	"io/ioutil"
+
+	"github.com/gopherjs/gopherjs/js"
+	"github.com/hajimehoshi/ebiten/audio"
+)
+
+// TODO: This just uses decodeAudioData can treat audio files other than MP3.
+
+type Stream struct {
+	leftData   []float32
+	rightData  []float32
+	posInBytes int
+}
+
+func (s *Stream) Read(b []byte) (int, error) {
+	l := len(s.leftData)*4 - s.posInBytes
+	if l > len(b) {
+		l = len(b)
+	}
+	l = l / 4 * 4
+	for i := 0; i < l/4; i++ {
+		il := int16(s.leftData[s.posInBytes/4+i] * (1 << 15))
+		ir := int16(s.rightData[s.posInBytes/4+i] * (1 << 15))
+		b[4*i] = uint8(il)
+		b[4*i+1] = uint8(il >> 8)
+		b[4*i+2] = uint8(ir)
+		b[4*i+3] = uint8(ir >> 8)
+	}
+	s.posInBytes += l
+	if s.posInBytes == len(s.leftData)*4 {
+		return l, io.EOF
+	}
+	return l, nil
+}
+
+func (s *Stream) Seek(offset int64, whence int) (int64, error) {
+	next := int64(0)
+	switch whence {
+	case 0:
+		next = offset
+	case 1:
+		next = int64(s.posInBytes) + offset
+	case 2:
+		next = int64(len(s.leftData)*4) + offset
+	}
+	s.posInBytes = int(next)
+	return next, nil
+}
+
+func (s *Stream) Close() error {
+	return nil
+}
+
+func (s *Stream) Size() int64 {
+	return int64(len(s.leftData) * 4)
+}
+
+func Decode(context *audio.Context, src audio.ReadSeekCloser) (*Stream, error) {
+	b, err := ioutil.ReadAll(src)
+	if err != nil {
+		return nil, err
+	}
+	if err := src.Close(); err != nil {
+		return nil, err
+	}
+	s := &Stream{}
+	ch := make(chan struct{})
+
+	klass := js.Global.Get("OfflineAudioContext")
+	if klass == js.Undefined {
+		klass = js.Global.Get("webkitOfflineAudioContext")
+	}
+	if klass == js.Undefined {
+		return nil, errors.New("vorbis: OfflineAudioContext is not available")
+	}
+	// TODO: 1 is a correct second argument?
+	oc := klass.New(2, 1, context.SampleRate())
+	oc.Call("decodeAudioData", js.NewArrayBuffer(b), func(buf *js.Object) {
+		s.leftData = buf.Call("getChannelData", 0).Interface().([]float32)
+		s.rightData = buf.Call("getChannelData", 1).Interface().([]float32)
+		close(ch)
+	})
+	<-ch
+	return s, nil
+}

audio/mp3/decode_notjs.go

@@ -12,14 +12,59 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// +build !js
+
+// Package mp3 provides MP3 decoder.
+//
+// This package is very experimental.
 package mp3
 
 import (
 	"github.com/hajimehoshi/go-mp3"
 
 	"github.com/hajimehoshi/ebiten/audio"
+	"github.com/hajimehoshi/ebiten/audio/internal/convert"
 )
 
-func decode(src audio.ReadSeekCloser) (*mp3.Decoded, error) {
-	return mp3.Decode(src)
+type Stream struct {
+	inner audio.ReadSeekCloser
+	size  int64
+}
+
+// Read is implementation of io.Reader's Read.
+func (s *Stream) Read(buf []byte) (int, error) {
+	return s.inner.Read(buf)
+}
+
+// Seek is implementation of io.Seeker's Seek.
+func (s *Stream) Seek(offset int64, whence int) (int64, error) {
+	return s.inner.Seek(offset, whence)
+}
+
+// Read is implementation of io.Closer's Close.
+func (s *Stream) Close() error {
+	return s.inner.Close()
+}
+
+// Size returns the size of decoded stream in bytes.
+func (s *Stream) Size() int64 {
+	return s.size
+}
+
+func Decode(context *audio.Context, src audio.ReadSeekCloser) (*Stream, error) {
+	d, err := mp3.Decode(src)
+	if err != nil {
+		return nil, err
+	}
+	// TODO: Resampling
+	var s audio.ReadSeekCloser = convert.NewSeeker(d)
+	size := d.Length()
+	if d.SampleRate() != context.SampleRate() {
+		s = convert.NewResampling(s, d.Length(), d.SampleRate(), context.SampleRate())
+		size = size * int64(context.SampleRate()) / int64(d.SampleRate())
+	}
+	return &Stream{
+		inner: s,
+		size:  size,
+	}, nil
 }