From 7a33837ed7cc91720ce4419aae3dfb771777e503 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Fri, 25 Mar 2022 20:46:59 +0900
Subject: [PATCH] audio: change the type of SetBufferSize to time.Duration

Updates #2026
---
 audio/audio.go               | 2 +-
 audio/player.go              | 8 +++++---
 examples/realtimepcm/main.go | 5 +++--
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/audio/audio.go b/audio/audio.go
index aaa52f385..ff8feae8e 100644
--- a/audio/audio.go
+++ b/audio/audio.go
@@ -403,7 +403,7 @@ func (p *Player) SetVolume(volume float64) {
 // If 0 is specified, the default buffer size is used.
 // A small buffer size is useful if you want to play a real-time PCM for example.
 // Note that the audio quality might be affected if you modify the buffer size.
-func (p *Player) SetBufferSize(bufferSize int) {
+func (p *Player) SetBufferSize(bufferSize time.Duration) {
 	p.p.SetBufferSize(bufferSize)
 }
 
diff --git a/audio/player.go b/audio/player.go
index bc462f703..cef0284c4 100644
--- a/audio/player.go
+++ b/audio/player.go
@@ -286,15 +286,17 @@ func (p *playerImpl) Err() error {
 	return p.player.Err()
 }
 
-func (p *playerImpl) SetBufferSize(bufferSize int) {
+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 = bufferSizeInBytes / bytesPerSample * bytesPerSample
 	if p.player == nil {
-		p.initBufferSize = bufferSize
+		p.initBufferSize = bufferSizeInBytes
 		return
 	}
-	p.player.SetBufferSize(bufferSize)
+	p.player.SetBufferSize(bufferSizeInBytes)
 }
 
 func (p *playerImpl) source() io.Reader {
diff --git a/examples/realtimepcm/main.go b/examples/realtimepcm/main.go
index 5900ecfe3..052466e60 100644
--- a/examples/realtimepcm/main.go
+++ b/examples/realtimepcm/main.go
@@ -21,6 +21,7 @@ import (
 	"log"
 	"math"
 	"sync"
+	"time"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/audio"
@@ -135,8 +136,8 @@ func (g *Game) Update() error {
 
 		// Adjust the buffer size to reflect the audio source changes in real time.
 		// Note that Ebiten doesn't guarantee the audio quality when the buffer size is modified.
-		// 8192 should work in most cases, but this might cause glitches in some environments.
-		g.player.SetBufferSize(8192)
+		// 1/20[s] should work in most cases, but this might cause glitches in some environments.
+		g.player.SetBufferSize(time.Second / 20)
 	}
 	g.sineWave.Update(ebiten.IsKeyPressed(ebiten.KeyA))
 	return nil