audio: Consume necessary and sufficient data on each Update (#205) (WIP)

exp/audio/audio.go

@@ -36,23 +36,14 @@ import (
 )
 
 type mixingStream struct {
-	sampleRate   int
-	writtenBytes int
-	frames       int
-	players      map[*Player]struct{}
+	sampleRate int
+	players    map[*Player]struct{}
 
 	// Note that Read (and other methods) need to be concurrent safe
 	// because Read is called from another groutine (see NewContext).
 	sync.RWMutex
 }
 
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
-
 const (
 	channelNum     = 2
 	bytesPerSample = 2
@@ -62,26 +53,24 @@ const (
 )
 
 func (s *mixingStream) SampleRate() int {
-	s.RLock()
-	defer s.RUnlock()
 	return s.sampleRate
 }
 
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
 func (s *mixingStream) Read(b []byte) (int, error) {
 	s.Lock()
 	defer s.Unlock()
 
-	bytesPerFrame := s.sampleRate * bytesPerSample * channelNum / ebiten.FPS
-	x := s.frames*bytesPerFrame + len(b)
-	if x <= s.writtenBytes {
-		return 0, nil
-	}
-
 	if len(s.players) == 0 {
-		l := min(len(b), x-s.writtenBytes)
+		l := len(b)
 		l &= mask
 		copy(b, make([]byte, l))
-		s.writtenBytes += l
 		return l, nil
 	}
 	closed := []*Player{}
@@ -120,17 +109,9 @@ func (s *mixingStream) Read(b []byte) (int, error) {
 	for _, p := range closed {
 		delete(s.players, p)
 	}
-	s.writtenBytes += l
 	return l, nil
 }
 
-func (s *mixingStream) update() error {
-	s.Lock()
-	defer s.Unlock()
-	s.frames++
-	return nil
-}
-
 func (s *mixingStream) newPlayer(src ReadSeekCloser) (*Player, error) {
 	s.Lock()
 	defer s.Unlock()
@@ -219,40 +200,26 @@ func (s *mixingStream) playerCurrent(player *Player) time.Duration {
 // You can also call Update independently from the game loop as 'async mode'.
 // In this case, audio goes on even when the game stops e.g. by diactivating the screen.
 type Context struct {
-	stream  *mixingStream
-	errorCh chan error
+	stream       *mixingStream
+	driver       *driver.Player
+	frames       int
+	writtenBytes int
 }
 
 // NewContext creates a new audio context with the given sample rate (e.g. 44100).
 func NewContext(sampleRate int) (*Context, error) {
 	// TODO: Panic if one context exists.
-	c := &Context{
-		errorCh: make(chan error),
-	}
+	c := &Context{}
 	c.stream = &mixingStream{
 		sampleRate: sampleRate,
 		players:    map[*Player]struct{}{},
 	}
 	// TODO: Rename this other than player
-	p, err := driver.NewPlayer(c.stream, sampleRate, channelNum, bytesPerSample)
+	p, err := driver.NewPlayer(sampleRate, channelNum, bytesPerSample)
+	c.driver = p
 	if err != nil {
 		return nil, err
 	}
-	go func() {
-		// TODO: Is it OK to close asap?
-		defer p.Close()
-		for {
-			err := p.Proceed()
-			if err == io.EOF {
-				break
-			}
-			if err != nil {
-				c.errorCh <- err
-				return
-			}
-			time.Sleep(1 * time.Millisecond)
-		}
-	}()
 	return c, nil
 }
 
@@ -264,12 +231,27 @@ func NewContext(sampleRate int) (*Context, error) {
 // you will find audio stops when the game stops e.g. when the window is deactivated.
 // In async mode, the audio never stops even when the game stops.
 func (c *Context) Update() error {
-	select {
-	case err := <-c.errorCh:
+	c.frames++
+	bytesPerFrame := c.stream.sampleRate * bytesPerSample * channelNum / ebiten.FPS
+	l := (c.frames * bytesPerFrame) - c.writtenBytes
+	l &= mask
+	c.writtenBytes += l
+	buf := make([]byte, l)
+	n, err := io.ReadFull(c.stream, buf)
+	if err != nil {
 		return err
-	default:
 	}
-	return c.stream.update()
+	if n != len(buf) {
+		return c.driver.Close()
+	}
+	err = c.driver.Proceed(buf)
+	if err == io.EOF {
+		return c.driver.Close()
+	}
+	if err != nil {
+		return err
+	}
+	return nil
 }
 
 // SampleRate returns the sample rate.

exp/audio/internal/driver/driver_js.go

@@ -18,13 +18,11 @@ package driver
 
 import (
 	"errors"
-	"io"
 
 	"github.com/gopherjs/gopherjs/js"
 )
 
 type Player struct {
-	src               io.Reader
 	sampleRate        int
 	channelNum        int
 	bytesPerSample    int
@@ -33,7 +31,7 @@ type Player struct {
 	bufferSource      *js.Object
 }
 
-func NewPlayer(src io.Reader, sampleRate, channelNum, bytesPerSample int) (*Player, error) {
+func NewPlayer(sampleRate, channelNum, bytesPerSample int) (*Player, error) {
 	class := js.Global.Get("AudioContext")
 	if class == js.Undefined {
 		class = js.Global.Get("webkitAudioContext")
@@ -42,7 +40,6 @@ func NewPlayer(src io.Reader, sampleRate, channelNum, bytesPerSample int) (*Play
 		return nil, errors.New("driver: audio couldn't be initialized")
 	}
 	p := &Player{
-		src:            src,
 		sampleRate:     sampleRate,
 		channelNum:     channelNum,
 		bytesPerSample: bytesPerSample,
@@ -63,37 +60,29 @@ func toLR(data []byte) ([]int16, []int16) {
 	return l, r
 }
 
-const (
-	// 1024 seems not enough (some noise remains after the tab is deactivated).
-	bufferSize = 2048
-)
-
-func (p *Player) Proceed() error {
+func (p *Player) Proceed(data []byte) error {
 	c := int64(p.context.Get("currentTime").Float() * float64(p.sampleRate))
 	if p.positionInSamples < c {
 		p.positionInSamples = c
 	}
-	b := make([]byte, bufferSize)
-	n, err := p.src.Read(b)
-	if 0 < n {
-		buf := p.context.Call("createBuffer", p.channelNum, n/p.bytesPerSample/p.channelNum, p.sampleRate)
-		l := buf.Call("getChannelData", 0)
-		r := buf.Call("getChannelData", 1)
-		il, ir := toLR(b[:n])
-		const max = 1 << 15
-		for i := 0; i < len(il); i++ {
-			l.SetIndex(i, float64(il[i])/max)
-			r.SetIndex(i, float64(ir[i])/max)
-		}
-		p.bufferSource = p.context.Call("createBufferSource")
-		p.bufferSource.Set("buffer", buf)
-		p.bufferSource.Call("connect", p.context.Get("destination"))
-		p.bufferSource.Call("start", float64(p.positionInSamples)/float64(p.sampleRate))
-		// Call 'stop' or we'll get noisy sound especially on Chrome.
-		p.bufferSource.Call("stop", float64(p.positionInSamples+int64(len(il)))/float64(p.sampleRate))
-		p.positionInSamples += int64(len(il))
+	n := len(data)
+	buf := p.context.Call("createBuffer", p.channelNum, n/p.bytesPerSample/p.channelNum, p.sampleRate)
+	l := buf.Call("getChannelData", 0)
+	r := buf.Call("getChannelData", 1)
+	il, ir := toLR(data)
+	const max = 1 << 15
+	for i := 0; i < len(il); i++ {
+		l.SetIndex(i, float64(il[i])/max)
+		r.SetIndex(i, float64(ir[i])/max)
 	}
-	return err
+	p.bufferSource = p.context.Call("createBufferSource")
+	p.bufferSource.Set("buffer", buf)
+	p.bufferSource.Call("connect", p.context.Get("destination"))
+	p.bufferSource.Call("start", float64(p.positionInSamples)/float64(p.sampleRate))
+	// Call 'stop' or we'll get noisy sound especially on Chrome.
+	p.bufferSource.Call("stop", float64(p.positionInSamples+int64(len(il)))/float64(p.sampleRate))
+	p.positionInSamples += int64(len(il))
+	return nil
 }
 
 func (p *Player) Close() error {

exp/audio/internal/driver/driver_openal.go

@@ -17,8 +17,8 @@
 package driver
 
 import (
+	"errors"
 	"fmt"
-	"io"
 	"runtime"
 
 	"github.com/hajimehoshi/go-openal/openal"
@@ -35,7 +35,6 @@ type Player struct {
 	alDevice   *openal.Device
 	alSource   openal.Source
 	alBuffers  []openal.Buffer
-	source     io.Reader
 	sampleRate int
 	isClosed   bool
 	alFormat   openal.Format
@@ -55,7 +54,7 @@ func alFormat(channelNum, bytesPerSample int) openal.Format {
 	panic(fmt.Sprintf("driver: invalid channel num (%d) or bytes per sample (%d)", channelNum, bytesPerSample))
 }
 
-func NewPlayer(src io.Reader, sampleRate, channelNum, bytesPerSample int) (*Player, error) {
+func NewPlayer(sampleRate, channelNum, bytesPerSample int) (*Player, error) {
 	d := openal.OpenDevice("")
 	if d == nil {
 		return nil, fmt.Errorf("driver: OpenDevice must not return nil")
@@ -78,39 +77,31 @@ func NewPlayer(src io.Reader, sampleRate, channelNum, bytesPerSample int) (*Play
 		alDevice:   d,
 		alSource:   s,
 		alBuffers:  []openal.Buffer{},
-		source:     src,
 		sampleRate: sampleRate,
 		alFormat:   alFormat(channelNum, bytesPerSample),
 	}
 	runtime.SetFinalizer(p, (*Player).Close)
 
 	bs := openal.NewBuffers(maxBufferNum)
+	const bufferSize = 1024
 	emptyBytes := make([]byte, bufferSize)
 	for _, b := range bs {
 		// Note that the third argument of only the first buffer is used.
 		b.SetData(p.alFormat, emptyBytes, int32(p.sampleRate))
-		p.alSource.QueueBuffer(b)
+		//p.alSource.QueueBuffer(b)
+		p.alBuffers = append(p.alBuffers, b)
 	}
 	p.alSource.Play()
 	return p, nil
 }
 
-const (
-	bufferSize = 1024
-)
-
-var (
-	tmpBuffer    = make([]byte, bufferSize)
-	tmpAlBuffers = make([]openal.Buffer, maxBufferNum)
-)
-
-func (p *Player) Proceed() error {
+func (p *Player) Proceed(data []byte) error {
 	if err := openal.Err(); err != nil {
 		return fmt.Errorf("driver: starting Proceed: %v", err)
 	}
 	processedNum := p.alSource.BuffersProcessed()
 	if 0 < processedNum {
-		bufs := tmpAlBuffers[:processedNum]
+		bufs := make([]openal.Buffer, processedNum)
 		p.alSource.UnqueueBuffers(bufs)
 		if err := openal.Err(); err != nil {
 			return fmt.Errorf("driver: UnqueueBuffers: %v", err)
@@ -118,20 +109,15 @@ func (p *Player) Proceed() error {
 		p.alBuffers = append(p.alBuffers, bufs...)
 	}
 
-	if 0 < len(p.alBuffers) {
-		n, err := p.source.Read(tmpBuffer)
-		if 0 < n {
-			buf := p.alBuffers[0]
-			p.alBuffers = p.alBuffers[1:]
-			buf.SetData(p.alFormat, tmpBuffer[:n], int32(p.sampleRate))
-			p.alSource.QueueBuffer(buf)
-			if err := openal.Err(); err != nil {
-				return fmt.Errorf("driver: QueueBuffer: %v", err)
-			}
-		}
-		if err != nil {
-			return err
-		}
+	if len(p.alBuffers) == 0 {
+		return errors.New("driver: p.alBuffers must > 0")
+	}
+	buf := p.alBuffers[0]
+	p.alBuffers = p.alBuffers[1:]
+	buf.SetData(p.alFormat, data, int32(p.sampleRate))
+	p.alSource.QueueBuffer(buf)
+	if err := openal.Err(); err != nil {
+		return fmt.Errorf("driver: QueueBuffer: %v", err)
 	}
 
 	if p.alSource.State() == openal.Stopped || p.alSource.State() == openal.Initial {

exp/audio/internal/driver/driver_windows.go

@@ -27,7 +27,6 @@ import "C"
 import (
 	"errors"
 	"fmt"
-	"io"
 	"unsafe"
 )
 
@@ -76,7 +75,6 @@ func releaseSemaphore() {
 }
 
 type Player struct {
-	src     io.Reader
 	out     C.HWAVEOUT
 	buffer  []byte
 	headers []*header
@@ -84,7 +82,7 @@ type Player struct {
 
 const bufferSize = 1024
 
-func NewPlayer(src io.Reader, sampleRate, channelNum, bytesPerSample int) (*Player, error) {
+func NewPlayer(sampleRate, channelNum, bytesPerSample int) (*Player, error) {
 	numBlockAlign := channelNum * bytesPerSample
 	f := C.WAVEFORMATEX{
 		wFormatTag:      C.WAVE_FORMAT_PCM,
@@ -99,7 +97,6 @@ func NewPlayer(src io.Reader, sampleRate, channelNum, bytesPerSample int) (*Play
 		return nil, fmt.Errorf("driver: waveOutOpen error: %d", err)
 	}
 	p := &Player{
-		src:     src,
 		out:     w,
 		buffer:  []byte{},
 		headers: make([]*header, numHeader),
@@ -114,35 +111,27 @@ func NewPlayer(src io.Reader, sampleRate, channelNum, bytesPerSample int) (*Play
 	return p, nil
 }
 
-func (p *Player) Proceed() error {
-	if len(p.buffer) < bufferSize {
-		b := make([]byte, bufferSize)
-		n, err := p.src.Read(b)
-		if 0 < n {
-			p.buffer = append(p.buffer, b[:n]...)
-		}
-		if err != nil {
-			return err
+func (p *Player) Proceed(data []byte) error {
+	p.buffer = append(p.buffer, data...)
+	if bufferSize > len(p.buffer) {
+		return nil
+	}
+	sem <- struct{}{}
+	headerToWrite := (*header)(nil)
+	for _, h := range p.headers {
+		// TODO: Need to check WHDR_DONE?
+		if h.waveHdr.dwFlags&C.WHDR_INQUEUE == 0 {
+			headerToWrite = h
+			break
 		}
 	}
-	if bufferSize <= len(p.buffer) {
-		sem <- struct{}{}
-		headerToWrite := (*header)(nil)
-		for _, h := range p.headers {
-			// TODO: Need to check WHDR_DONE?
-			if h.waveHdr.dwFlags&C.WHDR_INQUEUE == 0 {
-				headerToWrite = h
-				break
-			}
-		}
-		if headerToWrite == nil {
-			return errors.New("driver: no available buffers")
-		}
-		if err := headerToWrite.Write(p.out, p.buffer[:bufferSize]); err != nil {
-			return err
-		}
-		p.buffer = p.buffer[bufferSize:]
+	if headerToWrite == nil {
+		return errors.New("driver: no available buffers")
 	}
+	if err := headerToWrite.Write(p.out, p.buffer[:bufferSize]); err != nil {
+		return err
+	}
+	p.buffer = p.buffer[bufferSize:]
 	return nil
 }