audio: rename constants

Updates #2630

audio/audio.go

@@ -47,8 +47,8 @@ import (
 
 const (
 	channelCount         = 2
-	bitDepthInBytes = 2
+	bitDepthInBytesInt16 = 2
-	bytesPerSample  = bitDepthInBytes * channelCount
+	bytesPerSampleInt16  = bitDepthInBytesInt16 * channelCount
 )
 
 // A Context represents a current state of audio.

audio/context.go

@@ -24,7 +24,7 @@ func newContext(sampleRate int) (context, chan struct{}, error) {
 	ctx, ready, err := oto.NewContextWithOptions(&oto.NewContextOptions{
 		SampleRate:   sampleRate,
 		ChannelCount: channelCount,
-		Format:       bitDepthInBytes,
+		Format:       oto.FormatSignedInt16LE,
 	})
 	err = addErrorInfoForContextCreation(err)
 	return &contextProxy{ctx}, ready, err

audio/loop.go

@@ -26,7 +26,7 @@ type InfiniteLoop struct {
 	llength int64
 	pos     int64
 
-	// extra is the remainder in the case when the read byte sizes are not multiple of bitDepthInBytes.
+	// extra is the remainder in the case when the read byte sizes are not multiple of bitDepthInBytesInt16.
 	extra []byte
 
 	// afterLoop is data after the loop.
@@ -60,8 +60,8 @@ func NewInfiniteLoop(src io.ReadSeeker, length int64) *InfiniteLoop {
 func NewInfiniteLoopWithIntro(src io.ReadSeeker, introLength int64, loopLength int64) *InfiniteLoop {
 	return &InfiniteLoop{
 		src:     src,
-		lstart:  introLength / bytesPerSample * bytesPerSample,
+		lstart:  introLength / bytesPerSampleInt16 * bytesPerSampleInt16,
-		llength: loopLength / bytesPerSample * bytesPerSample,
+		llength: loopLength / bytesPerSampleInt16 * bytesPerSampleInt16,
 		pos:     -1,
 	}
 }
@@ -92,8 +92,8 @@ func (i *InfiniteLoop) blendRate(pos int64) float64 {
 	if pos >= i.lstart+int64(len(i.afterLoop)) {
 		return 0
 	}
-	p := (pos - i.lstart) / bytesPerSample
+	p := (pos - i.lstart) / bytesPerSampleInt16
-	l := len(i.afterLoop) / bytesPerSample
+	l := len(i.afterLoop) / bytesPerSampleInt16
 	return 1 - float64(p)/float64(l)
 }
 
@@ -119,7 +119,7 @@ func (i *InfiniteLoop) Read(b []byte) (int, error) {
 	}
 
 	// Save the remainder part to extra. This will be used at the next Read.
-	if rem := n % bitDepthInBytes; rem != 0 {
+	if rem := n % bitDepthInBytesInt16; rem != 0 {
 		i.extra = append(i.extra, b[n-rem:n]...)
 		b = b[:n-rem]
 		n = n - rem
@@ -128,17 +128,17 @@ func (i *InfiniteLoop) Read(b []byte) (int, error) {
 	// Blend afterLoop and the loop start to reduce noises (#1888).
 	// Ideally, afterLoop and the loop start should be identical, but they can have very slight differences.
 	if !i.noBlendForTesting && i.blending && i.pos >= i.lstart && i.pos-int64(n) < i.lstart+int64(len(i.afterLoop)) {
-		if n%bitDepthInBytes != 0 {
+		if n%bitDepthInBytesInt16 != 0 {
-			panic(fmt.Sprintf("audio: n must be a multiple of bitDepthInBytes but not: %d", n))
+			panic(fmt.Sprintf("audio: n must be a multiple of bitDepthInBytesInt16 but not: %d", n))
 		}
-		for idx := 0; idx < n/bitDepthInBytes; idx++ {
+		for idx := 0; idx < n/bitDepthInBytesInt16; idx++ {
-			abspos := i.pos - int64(n) + int64(idx)*bitDepthInBytes
+			abspos := i.pos - int64(n) + int64(idx)*bitDepthInBytesInt16
 			rate := i.blendRate(abspos)
 			if rate == 0 {
 				continue
 			}
 
-			// This assumes that bitDepthInBytes is 2.
+			// This assumes that bitDepthInBytesInt16 is 2.
 			relpos := abspos - i.lstart
 			afterLoop := int16(i.afterLoop[relpos]) | (int16(i.afterLoop[relpos+1]) << 8)
 			orig := int16(b[2*idx]) | (int16(b[2*idx+1]) << 8)
@@ -156,7 +156,7 @@ func (i *InfiniteLoop) Read(b []byte) (int, error) {
 	// Read the afterLoop part if necessary.
 	if i.pos == i.length() && err == nil {
 		if i.afterLoop == nil {
-			buflen := int64(256 * bytesPerSample)
+			buflen := int64(256 * bytesPerSampleInt16)
 			if buflen > i.length() {
 				buflen = i.length()
 			}

audio/player.go

@@ -251,7 +251,7 @@ func (p *playerImpl) Current() time.Duration {
 		return 0
 	}
 
-	samples := (p.stream.Current() - int64(p.player.UnplayedBufferSize())) / bytesPerSample
+	samples := (p.stream.Current() - int64(p.player.UnplayedBufferSize())) / bytesPerSampleInt16
 	return time.Duration(samples) * time.Second / time.Duration(p.factory.sampleRate)
 }
 
@@ -288,8 +288,8 @@ func (p *playerImpl) SetBufferSize(bufferSize time.Duration) {
 	p.m.Lock()
 	defer p.m.Unlock()
 
-	bufferSizeInBytes := int(bufferSize * bytesPerSample * time.Duration(p.factory.sampleRate) / time.Second)
+	bufferSizeInBytes := int(bufferSize * bytesPerSampleInt16 * time.Duration(p.factory.sampleRate) / time.Second)
-	bufferSizeInBytes = bufferSizeInBytes / bytesPerSample * bytesPerSample
+	bufferSizeInBytes = bufferSizeInBytes / bytesPerSampleInt16 * bytesPerSampleInt16
 	if p.player == nil {
 		p.initBufferSize = bufferSizeInBytes
 		return
@@ -358,11 +358,11 @@ func (s *timeStream) timeDurationToPos(offset time.Duration) int64 {
 	s.m.Lock()
 	defer s.m.Unlock()
 
-	o := int64(offset) * bytesPerSample * int64(s.sampleRate) / int64(time.Second)
+	o := int64(offset) * bytesPerSampleInt16 * int64(s.sampleRate) / int64(time.Second)
 
 	// Align the byte position with the samples.
-	o -= o % bytesPerSample
+	o -= o % bytesPerSampleInt16
-	o += s.pos % bytesPerSample
+	o += s.pos % bytesPerSampleInt16
 
 	return o
 }