Add Context.SetReadBufferSize.

driver.go

@@ -26,7 +26,8 @@ import (
 //
 // There can only be one context at any time. Closing a context and opening a new one is allowed.
 type Context struct {
-	context *context
+	context    *context
+	bufferSize int
 }
 
 // NewPlayer creates a new, ready-to-use Player belonging to the Context.
@@ -67,6 +68,17 @@ func (c *Context) Resume() error {
 	return c.context.Resume()
 }
 
+// SetReadBufferSize sets the size of buffer to read from the underlying source.
+//
+// This is useful for cases where you may need to sync visuals with audio.
+//
+// Setting this to 0 will have Oto automatically calculate a buffer size.
+//
+// SetReadBufferSize is not concurrent-safe.
+func (c *Context) SetReadBufferSize(readBufferSize int) {
+	c.context.readBufferSize = readBufferSize
+}
+
 // Err returns the current error.
 //
 // Err is concurrent-safe.
@@ -145,6 +157,9 @@ 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 {
+	if c.readBufferSize > 0 {
+		return c.readBufferSize
+	}
 	// The number of underlying buffers should be 2.
 	return c.oneBufferSize() * 2
 }

driver_android.go

@@ -22,6 +22,7 @@ type context struct {
 	sampleRate      int
 	channelNum      int
 	bitDepthInBytes int
+	readBufferSize  int
 
 	players *players
 }

driver_darwin.go

@@ -75,6 +75,7 @@ type context struct {
 	sampleRate      int
 	channelNum      int
 	bitDepthInBytes int
+	readBufferSize  int
 
 	audioQueue      C.AudioQueueRef
 	unqueuedBuffers []C.AudioQueueBufferRef

driver_js.go

@@ -32,6 +32,7 @@ type context struct {
 	sampleRate      int
 	channelNum      int
 	bitDepthInBytes int
+	readBufferSize  int
 }
 
 func newContext(sampleRate int, channelNum int, bitDepthInBytes int) (*context, chan struct{}, error) {

driver_unix.go

@@ -33,6 +33,7 @@ type context struct {
 	sampleRate      int
 	channelNum      int
 	bitDepthInBytes int
+	readBufferSize  int
 
 	suspended bool
 

driver_windows.go

@@ -69,6 +69,7 @@ type context struct {
 	sampleRate      int
 	channelNum      int
 	bitDepthInBytes int
+	readBufferSize  int
 
 	waveOut uintptr
 	headers []*header