Upgrade to Oto v2 & let Oto pull samples instead of pushing them to Oto

go.mod

@@ -5,7 +5,7 @@ go 1.14
 require (
 	github.com/gdamore/tcell v1.3.0
 	github.com/hajimehoshi/go-mp3 v0.3.0
-	github.com/hajimehoshi/oto v0.7.1
+	github.com/hajimehoshi/oto/v2 v2.4.0-alpha.4
 	github.com/jfreymuth/oggvorbis v1.0.1
 	github.com/mewkiz/flac v1.0.7
 	github.com/pkg/errors v0.9.1

go.sum

@@ -1,6 +1,8 @@
 github.com/DATA-DOG/go-sqlmock v1.3.3 h1:CWUqKXe0s8A2z6qCgkP4Kru7wC11YoAnoupUKFDnH08=
 github.com/DATA-DOG/go-sqlmock v1.3.3/go.mod h1:f/Ixk793poVmq4qj/V1dPUg2JEAKC73Q5eFN3EC/SaM=
 github.com/d4l3k/messagediff v1.2.2-0.20190829033028-7e0a312ae40b/go.mod h1:Oozbb1TVXFac9FtSIxHBMnBCq2qeH/2KkEQxENCrlLo=
+github.com/ebitengine/purego v0.0.0-20220907032450-cf3e27c364c7 h1:tmSauY5l3s/Cp5n+cEiG1epUR2AejmdHeMJMycMFxb0=
+github.com/ebitengine/purego v0.0.0-20220907032450-cf3e27c364c7/go.mod h1:Eh8I3yvknDYZeCuXH9kRNaPuHEwvXDCk378o9xszmHg=
 github.com/gdamore/encoding v1.0.0 h1:+7OoQ1Bc6eTm5niUzBa0Ctsh6JbMW6Ra+YNuAtDBdko=
 github.com/gdamore/encoding v1.0.0/go.mod h1:alR0ol34c49FCSBLjhosxzcPHQbf2trDkoo5dl+VrEg=
 github.com/gdamore/tcell v1.3.0 h1:r35w0JBADPZCVQijYebl6YMWWtHRqVEGt7kL2eBADRM=
@@ -12,10 +14,8 @@ github.com/hajimehoshi/go-mp3 v0.3.0 h1:fTM5DXjp/DL2G74HHAs/aBGiS9Tg7wnp+jkU38bH
 github.com/hajimehoshi/go-mp3 v0.3.0/go.mod h1:qMJj/CSDxx6CGHiZeCgbiq2DSUkbK0UbtXShQcnfyMM=
 github.com/hajimehoshi/oto v0.6.1 h1:7cJz/zRQV4aJvMSSRqzN2TImoVVMpE0BCY4nrNJaDOM=
 github.com/hajimehoshi/oto v0.6.1/go.mod h1:0QXGEkbuJRohbJaxr7ZQSxnju7hEhseiPx2hrh6raOI=
-github.com/hajimehoshi/oto v0.6.3 h1:NfrHdINv+7J8JhfkbHBROlWCzFSWc9PaHm2lS90KNzY=
-github.com/hajimehoshi/oto v0.6.3/go.mod h1:0QXGEkbuJRohbJaxr7ZQSxnju7hEhseiPx2hrh6raOI=
-github.com/hajimehoshi/oto v0.7.1 h1:I7maFPz5MBCwiutOrz++DLdbr4rTzBsbBuV2VpgU9kk=
-github.com/hajimehoshi/oto v0.7.1/go.mod h1:wovJ8WWMfFKvP587mhHgot/MBr4DnNy9m6EepeVGnos=
+github.com/hajimehoshi/oto/v2 v2.4.0-alpha.4 h1:m29xzbn3Pv5MgvgjMPs7m28uhUgVt3B3AIGjQLgkqUI=
+github.com/hajimehoshi/oto/v2 v2.4.0-alpha.4/go.mod h1:OdGUICBjy7upAjvqqacbB63XIuYR3fqXZ7kYtlVYJgQ=
 github.com/icza/bitio v1.0.0 h1:squ/m1SHyFeCA6+6Gyol1AxV9nmPPlJFT8c2vKdj3U8=
 github.com/icza/bitio v1.0.0/go.mod h1:0jGnlLAx8MKMr9VGnn/4YrvZiprkvBelsVIbA9Jjr9A=
 github.com/icza/mighty v0.0.0-20180919140131-cfd07d671de6 h1:8UsGZ2rr2ksmEru6lToqnXgA8Mz1DP11X4zSJ159C3k=
@@ -32,22 +32,18 @@ github.com/mewkiz/flac v1.0.7 h1:uIXEjnuXqdRaZttmSFM5v5Ukp4U6orrZsnYGGR3yow8=
 github.com/mewkiz/flac v1.0.7/go.mod h1:yU74UH277dBUpqxPouHSQIar3G1X/QIclVbFahSd1pU=
 github.com/mewkiz/pkg v0.0.0-20190919212034-518ade7978e2 h1:EyTNMdePWaoWsRSGQnXiSoQu0r6RS1eA557AwJhlzHU=
 github.com/mewkiz/pkg v0.0.0-20190919212034-518ade7978e2/go.mod h1:3E2FUC/qYUfM8+r9zAwpeHJzqRVVMIYnpzD/clwWxyA=
-github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
-golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8 h1:idBdZTd9UioThJp8KpM/rTSinK/ChZFBE43/WtIy8zg=
 golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/image v0.0.0-20190220214146-31aff87c08e9/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
-golang.org/x/image v0.0.0-20190227222117-0694c2d4d067 h1:KYGJGHOQy8oSi1fDlSpcZF0+juKwk/hEMv5SiwHogR0=
 golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
-golang.org/x/mobile v0.0.0-20190415191353-3e0bab5405d6 h1:vyLBGJPIl9ZYbcQFM2USFmJBK6KI+t+z6jL0lbwjrnc=
 golang.org/x/mobile v0.0.0-20190415191353-3e0bab5405d6/go.mod h1:E/iHnbuqvinMTCcRqshq8CkpyQDoeVncDDYHnLhea+o=
 golang.org/x/net v0.0.0-20190213061140-3a22650c66bd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/sys v0.0.0-20190312061237-fead79001313/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20190429190828-d89cdac9e872 h1:cGjJzUd8RgBw428LXP65YXni0aiGNA4Bl+ls8SmLOm8=
 golang.org/x/sys v0.0.0-20190429190828-d89cdac9e872/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20190626150813-e07cf5db2756 h1:9nuHUbU8dRnRRfj9KjWUVrJeoexdbeMjttk6Oh1rD10=
 golang.org/x/sys v0.0.0-20190626150813-e07cf5db2756/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20220712014510-0a85c31ab51e h1:NHvCuwuS43lGnYhten69ZWqi2QOj/CiDNcKbVqwVoew=
+golang.org/x/sys v0.0.0-20220712014510-0a85c31ab51e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

speaker/speaker.go

@@ -2,21 +2,22 @@
 package speaker
 
 import (
-	"sync"
-
 	"github.com/faiface/beep"
-	"github.com/hajimehoshi/oto"
+	"github.com/hajimehoshi/oto/v2"
 	"github.com/pkg/errors"
+	"io"
+	"sync"
 )
 
+const channelCount = 2
+const bitDepthInBytes = 2
+const bytesPerSample = bitDepthInBytes * channelCount
+
 var (
 	mu      sync.Mutex
 	mixer   beep.Mixer
-	samples [][2]float64
-	buf     []byte
 	context *oto.Context
-	player  *oto.Player
-	done    chan struct{}
+	player  oto.Player
 )
 
 // Init initializes audio playback through speaker. Must be called before using this package.
@@ -25,36 +26,23 @@ var (
 // bufferSize means lower CPU usage and more reliable playback. Lower bufferSize means better
 // responsiveness and less delay.
 func Init(sampleRate beep.SampleRate, bufferSize int) error {
-	mu.Lock()
-	defer mu.Unlock()
-
-	Close()
+	if context != nil {
+		return errors.New("speaker cannot be initialized more than once")
+	}
 
 	mixer = beep.Mixer{}
 
-	numBytes := bufferSize * 4
-	samples = make([][2]float64, bufferSize)
-	buf = make([]byte, numBytes)
-
 	var err error
-	context, err = oto.NewContext(int(sampleRate), 2, 2, numBytes)
+	var readyChan chan struct{}
+	context, readyChan, err = oto.NewContext(int(sampleRate), channelCount, bitDepthInBytes)
 	if err != nil {
 		return errors.Wrap(err, "failed to initialize speaker")
 	}
-	player = context.NewPlayer()
-
-	done = make(chan struct{})
+	<-readyChan
 
-	go func() {
-		for {
-			select {
-			default:
-				update()
-			case <-done:
-				return
-			}
-		}
-	}()
+	player = context.NewPlayer(newReaderFromStreamer(&mixer))
+	player.(oto.BufferSizeSetter).SetBufferSize(bufferSize * bytesPerSample)
+	player.Play()
 
 	return nil
 }
@@ -63,19 +51,16 @@ func Init(sampleRate beep.SampleRate, bufferSize int) error {
 // even when the program doesn't play anymore, because in properly set systems, the default mixer
 // handles multiple concurrent processes. It's only when the default device is not a virtual but hardware
 // device, that you'll probably want to manually manage the device from your application.
+//
+// TODO: investigate what happens now that oto.Context doesn't have a Close method.
 func Close() {
 	if player != nil {
-		if done != nil {
-			done <- struct{}{}
-			done = nil
-		}
 		player.Close()
-		context.Close()
 		player = nil
 	}
 }
 
-// Lock locks the speaker. While locked, speaker won't pull new data from the playing Stramers. Lock
+// Lock locks the speaker. While locked, speaker won't pull new data from the playing Streamers. Lock
 // if you want to modify any currently playing Streamers to avoid race conditions.
 //
 // Always lock speaker for as little time as possible, to avoid playback glitches.
@@ -102,16 +87,46 @@ func Clear() {
 	mu.Unlock()
 }
 
-// update pulls new data from the playing Streamers and sends it to the speaker. Blocks until the
-// data is sent and started playing.
-func update() {
+// sampleReader is a wrapper for beep.Streamer to implement io.Reader.
+type sampleReader struct {
+	s   beep.Streamer
+	buf [][2]float64
+}
+
+func newReaderFromStreamer(s beep.Streamer) *sampleReader {
+	return &sampleReader{
+		s: s,
+	}
+}
+
+// Read pulls samples from the reader and fills buf with the encoded
+// samples. Read expects the size of buf be divisible by the length
+// of a sample (= channel count * bit depth in bytes).
+func (s *sampleReader) Read(buf []byte) (n int, err error) {
+	// Read samples from streamer
+	if len(buf)%bytesPerSample != 0 {
+		return 0, errors.New("requested number of bytes do not align with the samples")
+	}
+	ns := len(buf) / bytesPerSample
+	if len(s.buf) < ns {
+		s.buf = make([][2]float64, ns)
+	}
 	mu.Lock()
-	mixer.Stream(samples)
+	ns, ok := s.s.Stream(s.buf[:ns])
 	mu.Unlock()
+	if !ok {
+		if s.s.Err() != nil {
+			return 0, errors.Wrap(s.s.Err(), "streamer returned error when requesting samples")
+		}
+		if ns == 0 {
+			return 0, io.EOF
+		}
+	}
 
-	for i := range samples {
-		for c := range samples[i] {
-			val := samples[i][c]
+	// Convert samples to bytes
+	for i := range s.buf[:ns] {
+		for c := range s.buf[i] {
+			val := s.buf[i][c]
 			if val < -1 {
 				val = -1
 			}
@@ -121,10 +136,10 @@ func update() {
 			valInt16 := int16(val * (1<<15 - 1))
 			low := byte(valInt16)
 			high := byte(valInt16 >> 8)
-			buf[i*4+c*2+0] = low
-			buf[i*4+c*2+1] = high
+			buf[i*bytesPerSample+c*bitDepthInBytes+0] = low
+			buf[i*bytesPerSample+c*bitDepthInBytes+1] = high
 		}
 	}
 
-	player.Write(buf)
+	return ns * bytesPerSample, nil
 }