audio/internal/readerplayer: Move the buffer for resuming to the driver side

Closes #1633

audio/internal/readerdriver/driver.go

@@ -20,7 +20,6 @@ import (
 
 type Context interface {
 	NewPlayer(io.Reader) Player
-	MaxBufferSize() int
 	Suspend() error
 	Resume() error
 	io.Closer
@@ -59,7 +58,7 @@ func (c *context) oneBufferSize() int {
 
 // maxBufferSize returns the maximum size of the buffer for the audio source.
 // This buffer is used when unreading on pausing the player.
-func (c *context) MaxBufferSize() int {
+func (c *context) maxBufferSize() int {
 	// The number of underlying buffers should be 2.
 	return c.oneBufferSize() * 2
 }

audio/internal/readerdriver/driver_android.go

@@ -80,8 +80,22 @@ type player struct {
 }
 
 func (p *player) Pause() {
-	// TODO: Implement the 'true' pause after #1633 is fixed.
-	p.Reset()
+	p.cond.L.Lock()
+	defer p.cond.L.Unlock()
+
+	if p.err != nil {
+		return
+	}
+	if p.closed {
+		return
+	}
+	if p.p == nil {
+		return
+	}
+	if err := p.p.Pause(); err != nil {
+		p.setErrorImpl(err)
+		return
+	}
 }
 
 func (p *player) Play() {
@@ -224,10 +238,10 @@ func (p *player) shouldWait() bool {
 	if p.p == nil {
 		return false
 	}
-	if !p.p.IsPlaying() {
-		return false
+	if p.p.IsPlaying() {
+		return p.p.UnplayedBufferSize() >= int64(p.context.maxBufferSize())
 	}
-	return p.p.UnplayedBufferSize() >= int64(p.context.MaxBufferSize())
+	return true
 }
 
 func (p *player) wait() bool {

audio/internal/readerdriver/driver_js.go

@@ -137,11 +137,17 @@ func (p *player) Pause() {
 	}
 
 	// Change the state first. appendBuffer is called as an 'ended' callback.
+	var data [2][]float32
 	for _, n := range p.bufferSourceNodes {
+		for ch := 0; ch < 2; ch++ {
+			t := n.Get("buffer").Call("getChannelData", ch)
+			data[ch] = append(data[ch], float32ArrayToFloat32Slice(t)...)
+		}
 		n.Set("onended", nil)
 		n.Call("stop")
 		n.Call("disconnect")
 	}
+	p.buf = append(fromLR(data[0], data[1]), p.buf...)
 	p.state = playerPaused
 	p.bufferSourceNodes = p.bufferSourceNodes[:0]
 	p.nextPos = 0
@@ -264,7 +270,7 @@ func (p *player) UnplayedBufferSize() int64 {
 	for _, n := range p.bufferSourceNodes {
 		sec += n.Get("buffer").Get("duration").Float()
 	}
-	return int64(sec * float64(p.context.sampleRate*p.context.channelNum*p.context.bitDepthInBytes))
+	return int64(len(p.buf)) + int64(sec*float64(p.context.sampleRate*p.context.channelNum*p.context.bitDepthInBytes))
 }
 
 func (p *player) Err() error {
@@ -287,10 +293,6 @@ func (w *go2cppDriverWrapper) NewPlayer(r io.Reader) Player {
 	return w.c.NewPlayer(r)
 }
 
-func (w *go2cppDriverWrapper) MaxBufferSize() int {
-	return w.c.MaxBufferSize()
-}
-
 func (w *go2cppDriverWrapper) Suspend() error {
 	// Do nothing so far.
 	return nil
@@ -317,6 +319,24 @@ func toLR(data []byte) ([]float32, []float32) {
 	return l, r
 }
 
+func fromLR(l, r []float32) []byte {
+	const max = 1 << 15
+
+	if len(l) != len(r) {
+		panic("readerdriver: len(l) must equal to len(r) at fromLR")
+	}
+	bs := make([]byte, len(l)*4)
+	for i := range l {
+		lv := int16(l[i] * max)
+		bs[4*i] = byte(lv)
+		bs[4*i+1] = byte(lv >> 8)
+		rv := int16(r[i] * max)
+		bs[4*i+2] = byte(rv)
+		bs[4*i+3] = byte(rv >> 8)
+	}
+	return bs
+}
+
 func float32SliceToTypedArray(s []float32) js.Value {
 	h := (*reflect.SliceHeader)(unsafe.Pointer(&s))
 	h.Len *= 4
@@ -329,3 +349,16 @@ func float32SliceToTypedArray(s []float32) js.Value {
 	buf := a.Get("buffer")
 	return js.Global().Get("Float32Array").New(buf, a.Get("byteOffset"), a.Get("byteLength").Int()/4)
 }
+
+func float32ArrayToFloat32Slice(v js.Value) []float32 {
+	bs := make([]byte, v.Get("byteLength").Int())
+	js.CopyBytesToGo(bs, js.Global().Get("Uint8Array").New(v.Get("buffer"), v.Get("byteOffset"), v.Get("byteLength")))
+
+	h := (*reflect.SliceHeader)(unsafe.Pointer(&bs))
+	h.Len /= 4
+	h.Cap /= 4
+	f32s := *(*[]float32)(unsafe.Pointer(h))
+	runtime.KeepAlive(bs)
+
+	return f32s
+}

audio/readerplayer.go

@@ -92,7 +92,7 @@ func (p *readerPlayer) ensurePlayer() error {
 		p.factory.context = c
 	}
 	if p.stream == nil {
-		s, err := newTimeStream(p.src, p.factory.sampleRate, p.factory.context.MaxBufferSize())
+		s, err := newTimeStream(p.src, p.factory.sampleRate)
 		if err != nil {
 			return err
 		}
@@ -130,9 +130,7 @@ func (p *readerPlayer) Pause() {
 		return
 	}
 
-	n := p.player.UnplayedBufferSize()
 	p.player.Pause()
-	p.stream.Unread(int(n))
 	p.context.removePlayer(p)
 }
 
@@ -231,23 +229,19 @@ func (p *readerPlayer) source() io.Reader {
 }
 
 type timeStream struct {
-	r             io.Reader
-	sampleRate    int
-	pos           int64
-	buf           []byte
-	unread        int
-	maxBufferSize int
+	r          io.Reader
+	sampleRate int
+	pos        int64
 
 	// m is a mutex for this stream.
 	// All the exported functions are protected by this mutex as Read can be read from a different goroutine than Seek.
 	m sync.Mutex
 }
 
-func newTimeStream(r io.Reader, sampleRate int, maxBufferSize int) (*timeStream, error) {
+func newTimeStream(r io.Reader, sampleRate int) (*timeStream, error) {
 	s := &timeStream{
-		r:             r,
-		sampleRate:    sampleRate,
-		maxBufferSize: maxBufferSize,
+		r:          r,
+		sampleRate: sampleRate,
 	}
 	if seeker, ok := s.r.(io.Seeker); ok {
 		// Get the current position of the source.
@@ -260,35 +254,12 @@ func newTimeStream(r io.Reader, sampleRate int, maxBufferSize int) (*timeStream,
 	return s, nil
 }
 
-func (s *timeStream) Unread(n int) {
-	s.m.Lock()
-	defer s.m.Unlock()
-
-	if s.unread+n > len(s.buf) {
-		// This should not happen usually, but the player's UnplayedBufferSize can include some errors.
-		n = len(s.buf) - s.unread
-	}
-	s.unread += n
-	s.pos -= int64(n)
-}
-
 func (s *timeStream) Read(buf []byte) (int, error) {
 	s.m.Lock()
 	defer s.m.Unlock()
 
-	if s.unread > 0 {
-		n := copy(buf, s.buf[len(s.buf)-s.unread:])
-		s.unread -= n
-		s.pos += int64(n)
-		return n, nil
-	}
-
 	n, err := s.r.Read(buf)
 	s.pos += int64(n)
-	s.buf = append(s.buf, buf[:n]...)
-	if m := s.maxBufferSize; len(s.buf) > m {
-		s.buf = s.buf[len(s.buf)-m:]
-	}
 	return n, err
 }
 
@@ -312,8 +283,6 @@ func (s *timeStream) Seek(offset time.Duration) error {
 	}
 
 	s.pos = pos
-	s.buf = s.buf[:0]
-	s.unread = 0
 	return nil
 }