#15 Android add OpenSL ES support for low latency audio output

src/platform/android/app/CMakeLists.txt

@@ -12,4 +12,4 @@ add_library( game SHARED
 
 include_directories(../../../)
 
-target_link_libraries( game GLESv2 log )
+target_link_libraries( game GLESv3 OpenSLES log )

src/platform/android/app/src/main/AndroidManifest.xml

@@ -7,6 +7,7 @@
     <supports-screens android:smallScreens="true" android:largeScreens="true" android:normalScreens="true" android:xlargeScreens="true" />
 
     <uses-feature android:glEsVersion="0x00020000" android:required="true" />
+    <uses-feature android:name="android.hardware.audio.low_latency" />
     <!--
         <uses-permission android:name="android.permission.INTERNET" />
         <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

src/platform/android/app/src/main/cpp/main.cpp

@@ -5,6 +5,8 @@
 #include <math.h>
 #include <pthread.h>
 #include <cstring>
+#include <SLES/OpenSLES.h>
+#include <SLES/OpenSLES_Android.h>
 
 #include "game.h"
 
@@ -23,6 +25,88 @@ int osGetTime() {
     return int((t.tv_sec - startTime) * 1000 + t.tv_usec / 1000);
 }
 
+// sound
+#define          SND_FRAMES 1176
+
+Sound::Frame     sndBuf[2][SND_FRAMES];
+int              sndBufIndex;
+
+SLObjectItf      sndEngine;
+SLObjectItf      sndOutput;
+SLObjectItf      sndPlayer;
+SLBufferQueueItf sndQueue = NULL;
+SLPlayItf        sndPlay  = NULL;
+
+void sndFill(SLBufferQueueItf bq, void *context) {
+    if (!sndQueue) return;
+    Sound::fill(sndBuf[sndBufIndex ^= 1], SND_FRAMES);
+    (*sndQueue)->Enqueue(sndQueue, sndBuf[sndBufIndex], SND_FRAMES * sizeof(Sound::Frame));
+}
+
+void sndSetState(bool active) {
+    if (!sndPlay) return;
+    (*sndPlay)->SetPlayState(sndPlay, active ? SL_PLAYSTATE_PLAYING : SL_PLAYSTATE_PAUSED);
+}
+
+void sndInit() {
+    slCreateEngine(&sndEngine, 0, NULL, 0, NULL, NULL);
+    (*sndEngine)->Realize(sndEngine, SL_BOOLEAN_FALSE);
+
+    SLEngineItf engine;
+
+    (*sndEngine)->GetInterface(sndEngine, SL_IID_ENGINE, &engine);
+    (*engine)->CreateOutputMix(engine, &sndOutput, 0, NULL, NULL);
+    (*sndOutput)->Realize(sndOutput, SL_BOOLEAN_FALSE);
+
+    SLDataFormat_PCM bufFormat;
+    bufFormat.formatType    = SL_DATAFORMAT_PCM;
+    bufFormat.numChannels   = 2;
+    bufFormat.samplesPerSec = SL_SAMPLINGRATE_44_1;
+    bufFormat.bitsPerSample = SL_PCMSAMPLEFORMAT_FIXED_16;
+    bufFormat.containerSize = SL_PCMSAMPLEFORMAT_FIXED_16;
+    bufFormat.channelMask   = SL_SPEAKER_FRONT_LEFT | SL_SPEAKER_FRONT_RIGHT ;
+    bufFormat.endianness    = SL_BYTEORDER_LITTLEENDIAN;
+
+    SLDataLocator_AndroidSimpleBufferQueue bufLocator;
+    bufLocator.locatorType = SL_DATALOCATOR_ANDROIDSIMPLEBUFFERQUEUE;
+    bufLocator.numBuffers  = 2;
+    
+    SLDataLocator_OutputMix snkLocator;
+    snkLocator.locatorType = SL_DATALOCATOR_OUTPUTMIX;
+    snkLocator.outputMix   = sndOutput;
+
+    SLDataSource audioSrc;
+    audioSrc.pLocator = &bufLocator;
+    audioSrc.pFormat  = &bufFormat;
+
+    SLDataSink audioSnk;
+    audioSnk.pLocator = &snkLocator;
+    audioSnk.pFormat  = NULL;
+
+    SLInterfaceID audioInt[] = { SL_IID_BUFFERQUEUE, SL_IID_PLAY  };
+    SLboolean     audioReq[] = { SL_BOOLEAN_TRUE, SL_BOOLEAN_TRUE };
+
+    (*engine)->CreateAudioPlayer(engine, &sndPlayer, &audioSrc, &audioSnk, 2, audioInt, audioReq);
+    (*sndPlayer)->Realize(sndPlayer, SL_BOOLEAN_FALSE);
+    (*sndPlayer)->GetInterface(sndPlayer, SL_IID_BUFFERQUEUE, &sndQueue);
+    (*sndPlayer)->GetInterface(sndPlayer, SL_IID_PLAY, &sndPlay);
+    (*sndQueue)->RegisterCallback(sndQueue, sndFill, NULL);
+
+    sndBufIndex = 1;
+    sndFill(sndQueue, NULL);
+    sndFill(sndQueue, NULL);
+}
+
+void sndFree() {
+    if (sndPlayer) (*sndPlayer)->Destroy(sndPlayer);
+    if (sndOutput) (*sndOutput)->Destroy(sndOutput);
+    if (sndEngine) (*sndEngine)->Destroy(sndEngine);
+    sndPlayer = sndOutput = sndEngine = NULL;
+    sndQueue = NULL;
+    sndPlay  = NULL;
+}
+
+
 // joystick
 bool osJoyReady(int index) {
     return index == 0;
@@ -65,12 +149,15 @@ JNI_METHOD(void, nativeInit)(JNIEnv* env, jobject obj, jstring jcontentDir, jstr
 
     strcpy(saveDir, cacheDir);
 
+    sndInit();
+
     glGetIntegerv(GL_FRAMEBUFFER_BINDING, (GLint*)&GAPI::defaultFBO);
     Game::init();
 }
 
 JNI_METHOD(void, nativeFree)(JNIEnv* env) {
     Game::deinit();
+    sndFree();
 }
 
 JNI_METHOD(void, nativeReset)(JNIEnv* env) {
@@ -182,11 +269,8 @@ JNI_METHOD(void, nativeSetEye)(JNIEnv* env, jobject obj, jint eye, jfloatArray p
     env->ReleaseFloatArrayElements(view, mView, 0);
 }
 
-JNI_METHOD(void, nativeSoundFill)(JNIEnv* env, jobject obj, jshortArray buffer) {
-    jshort *frames = env->GetShortArrayElements(buffer, NULL);
-    jsize count = env->GetArrayLength(buffer) / 2;
-    Sound::fill((Sound::Frame*)frames, count);
-    env->ReleaseShortArrayElements(buffer, frames, 0);
+JNI_METHOD(void, nativeSoundState)(JNIEnv* env, jobject obj, jboolean active) {
+    sndSetState(active);
 }
 
-}
+}

src/platform/android/app/src/main/java/org/xproger/openlara/MainActivity.java

@@ -2,9 +2,6 @@ package org.xproger.openlara;
 
 import java.util.ArrayList;
 import javax.microedition.khronos.egl.EGLConfig;
-import android.media.AudioFormat;
-import android.media.AudioManager;
-import android.media.AudioTrack;
 import android.os.Bundle;
 import android.os.Environment;
 import android.view.InputDevice;
@@ -14,16 +11,12 @@ import android.view.View;
 import android.view.View.OnGenericMotionListener;
 import android.view.View.OnKeyListener;
 import android.view.View.OnTouchListener;
-import android.view.Window;
-import android.view.WindowManager;
 
-import com.google.vr.sdk.base.AndroidCompat;
 import com.google.vr.sdk.base.Eye;
 import com.google.vr.sdk.base.GvrActivity;
 import com.google.vr.sdk.base.GvrView;
 import com.google.vr.sdk.base.HeadTransform;
 import com.google.vr.sdk.base.Viewport;
-import android.app.Activity;
 
 public class MainActivity extends GvrActivity implements OnTouchListener, OnKeyListener, OnGenericMotionListener {
     static GvrView gvrView;
@@ -218,79 +211,6 @@ public class MainActivity extends GvrActivity implements OnTouchListener, OnKeyL
     }
 }
 
-// @TODO: use native OpenSL ES
-class Sound {
-    private short buffer[];
-    private static AudioTrack audioTrack;
-
-    void start(final Wrapper wrapper) {
-        int rate = 44100;
-        int size = AudioTrack.getMinBufferSize(rate, AudioFormat.CHANNEL_OUT_STEREO, AudioFormat.ENCODING_PCM_16BIT);
-        size /= 2; // bytes -> words
-        while (size % 4704 != 0) size++;
-        //System.out.println(String.format("sound buffer size: %d", size));
-        buffer = new short[size];
-
-        try {
-            audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, 44100, AudioFormat.CHANNEL_OUT_STEREO,
-                    AudioFormat.ENCODING_PCM_16BIT, size * 2, AudioTrack.MODE_STREAM);
-        }catch (IllegalArgumentException e){
-            System.out.println("Error: buffer size is zero");
-            return;
-        }
-
-        try {
-            audioTrack.play();
-        }catch (NullPointerException e){
-            System.out.println("Error: audioTrack null pointer on start()");
-            return;
-        }
-
-        new Thread( new Runnable() {
-            public void run() {
-                while ( audioTrack.getPlayState() != AudioTrack.PLAYSTATE_STOPPED ) {
-                    if (audioTrack.getPlayState() == AudioTrack.PLAYSTATE_PLAYING && wrapper.ready) {
-                        Wrapper.nativeSoundFill(buffer);
-                        audioTrack.write(buffer, 0, buffer.length);
-                        audioTrack.flush();
-                    } else
-                        try {
-                            Thread.sleep(10);
-                        } catch(Exception e) {
-                            //
-                        }
-                }
-            }
-        } ).start();
-    }
-
-    void stop() {
-        try {
-            audioTrack.flush();
-            audioTrack.stop();
-            audioTrack.release();
-        }catch (NullPointerException e){
-            System.out.println("Error: audioTrack null pointer on stop()");
-        }
-    }
-
-    void play() {
-        try {
-            audioTrack.play();
-        }catch (NullPointerException e){
-            System.out.println("Error: audioTrack null pointer on play()");
-        }
-    }
-
-    void pause() {
-        try {
-            audioTrack.pause();
-        }catch (NullPointerException e){
-            System.out.println("Error: audioTrack null pointer on pause()");
-        };
-    }
-}
-
 class Touch {
     int id, state;
     float x, y;
@@ -315,34 +235,29 @@ class Wrapper implements GvrView.StereoRenderer {
     public static native void nativeFrameEnd();
     public static native void nativeFrameRender();
     public static native void nativeTouch(int id, int state, float x, float y);
-    public static native void nativeSoundFill(short buffer[]);
+    public static native void nativeSoundState(boolean active);
 
     Boolean ready = false;
     Boolean toggleVR = false;
     private String contentDir;
     private String cacheDir;
     private ArrayList<Touch> touch = new ArrayList<>();
-    private Sound sound;
 
     void onCreate(String contentDir, String cacheDir) {
         this.contentDir  = contentDir;
         this.cacheDir    = cacheDir;
-
-        sound = new Sound();
-        sound.start(this);
     }
 
     void onDestroy() {
-        sound.stop();
         nativeFree();
     }
 
     void onPause() {
-        sound.pause();
+        nativeSoundState(false);
     }
 
     void onResume() {
-        sound.play();
+        nativeSoundState(true);
         if (ready) nativeReset();
     }
 
@@ -361,7 +276,7 @@ class Wrapper implements GvrView.StereoRenderer {
     public void onSurfaceCreated(EGLConfig config) {
         if (!ready) {
             nativeInit(contentDir, cacheDir);
-            sound.play();
+            nativeSoundState(true);
             ready = true;
         }
     }