audio: Grace returning when audio is not available

.travis.yml

@@ -9,7 +9,7 @@ before_install:
   - sudo add-apt-repository 'deb http://us.archive.ubuntu.com/ubuntu/ utopic main restricted universe multiverse'
   - sudo add-apt-repository 'deb http://us.archive.ubuntu.com/ubuntu/ utopic-updates main restricted universe multiverse'
   - sudo apt-get update -qq
-  - sudo apt-get install -qq libglew-dev libglfw3-dev libopenal1 libopenal-dev
+  - sudo apt-get install -qq libglew-dev libglfw3-dev libopenal-dev libalut-dev
   - export NODE_PATH=$(npm config get prefix)/lib/node_modules
   - npm install --global gl
 

internal/audio/audio.go

@@ -18,6 +18,8 @@ import (
 	"sync"
 )
 
+var audioEnabled = false
+
 const bufferSize = 1024
 const SampleRate = 44100
 
@@ -75,6 +77,10 @@ func Play(channel int, l []float32, r []float32) bool {
 	channelsLock.Lock()
 	defer channelsLock.Unlock()
 
+	if !audioEnabled {
+		return false
+	}
+
 	if len(l) != len(r) {
 		panic("len(l) must equal to len(r)")
 	}
@@ -93,6 +99,10 @@ func Queue(channel int, l []float32, r []float32) {
 	channelsLock.Lock()
 	defer channelsLock.Unlock()
 
+	if !audioEnabled {
+		return
+	}
+
 	if len(l) != len(r) {
 		panic("len(l) must equal to len(r)")
 	}
@@ -116,6 +126,10 @@ func isChannelsEmpty() bool {
 	channelsLock.Lock()
 	defer channelsLock.Unlock()
 
+	if !audioEnabled {
+		return true
+	}
+
 	for _, ch := range channels {
 		if 0 < len(ch.l) {
 			return false
@@ -128,6 +142,10 @@ func loadChannelBuffers() (l, r []float32) {
 	channelsLock.Lock()
 	defer channelsLock.Unlock()
 
+	if !audioEnabled {
+		return nil, nil
+	}
+
 	inputL := make([]float32, bufferSize)
 	inputR := make([]float32, bufferSize)
 	for _, ch := range channels {
@@ -150,5 +168,9 @@ func IsPlaying(channel int) bool {
 	channelsLock.Lock()
 	defer channelsLock.Unlock()
 
+	if !audioEnabled {
+		return false
+	}
+
 	return isPlaying(channel)
 }

internal/audio/audio_js.go

@@ -49,6 +49,7 @@ func initialize() {
 			r.SetIndex(i, inputR[i])
 		}
 	})
+	audioEnabled = true
 }
 
 func start() {

internal/audio/audio_openal.go

@@ -21,6 +21,7 @@ import (
 	"encoding/binary"
 	"fmt"
 	"github.com/timshannon/go-openal/openal"
+	"log"
 	"math"
 	"runtime"
 	"time"
@@ -55,12 +56,14 @@ func initialize() {
 		context := device.CreateContext()
 		context.Activate()
 
-		source := openal.NewSource()
-
 		if alErr := openal.GetError(); alErr != 0 {
-			panic(fmt.Sprintf("OpenAL initialize error: %d", alErr))
+			log.Printf("OpenAL initialize error: %d", alErr)
+			close(ch)
+			return
 		}
 
+		audioEnabled = true
+		source := openal.NewSource()
 		close(ch)
 
 		emptyBytes := make([]byte, 4*bufferSize)