initial: oboe, logging

2026-02-01 02:54:05 +01:00
commit 8b6de6a883
45 changed files with 1514 additions and 0 deletions
--- a/app/.gitignore
+++ b/app/.gitignore
@@ -0,0 +1 @@
+/build
--- a/app/CMakeLists.txt
+++ b/app/CMakeLists.txt
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -0,0 +1,83 @@
+plugins {
+    alias(libs.plugins.android.application)
+    alias(libs.plugins.kotlin.android)
+}
+
+android {
+    namespace 'at.lockstep'
+    compileSdk 34
+
+    defaultConfig {
+        applicationId "at.lockstep"
+        minSdk 24
+        targetSdk 34
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+        vectorDrawables {
+            useSupportLibrary true
+        }
+        externalNativeBuild {
+            cmake {
+                //path 'src/main/cpp/CMakeLists.txt'
+                cppFlags ''
+                arguments "-DANDROID_STL=c++_shared"
+            }
+        }
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
+    buildFeatures {
+        compose true
+        prefab true
+    }
+    composeOptions {
+        kotlinCompilerExtensionVersion '1.5.1'
+    }
+    packaging {
+        resources {
+            excludes += '/META-INF/{AL2.0,LGPL2.1}'
+        }
+    }
+    externalNativeBuild {
+        cmake {
+            path file('src/main/cpp/CMakeLists.txt')
+            version '3.22.1'
+        }
+    }
+}
+
+dependencies {
+    implementation libs.oboe
+    implementation libs.slf4j.api
+    implementation libs.logback.android
+
+    implementation libs.androidx.core.ktx
+    implementation libs.androidx.lifecycle.runtime.ktx
+    implementation libs.androidx.activity.compose
+    implementation platform(libs.androidx.compose.bom)
+    implementation libs.androidx.ui
+    implementation libs.androidx.ui.graphics
+    implementation libs.androidx.ui.tooling.preview
+    implementation libs.androidx.material3
+    testImplementation libs.junit
+    androidTestImplementation libs.androidx.junit
+    androidTestImplementation libs.androidx.espresso.core
+    androidTestImplementation platform(libs.androidx.compose.bom)
+    androidTestImplementation libs.androidx.ui.test.junit4
+    debugImplementation libs.androidx.ui.tooling
+    debugImplementation libs.androidx.ui.test.manifest
+}
--- a/app/proguard-rules.pro
+++ b/app/proguard-rules.pro
@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <application
+        android:allowBackup="true"
+        android:dataExtractionRules="@xml/data_extraction_rules"
+        android:fullBackupContent="@xml/backup_rules"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.Lockstep"
+        tools:targetApi="31">
+        <activity
+            android:name="at.lockstep.app.MainActivity"
+            android:exported="true"
+            android:label="@string/app_name"
+            android:theme="@style/Theme.Lockstep">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>
--- a/app/src/main/assets/logback.xml
+++ b/app/src/main/assets/logback.xml
@@ -0,0 +1,27 @@
+<configuration>
+    <property name="LOG_DIR" value="/data/data/at.lockstep.app/files" />
+
+    <appender name="logcat" class="ch.qos.logback.classic.android.LogcatAppender">
+        <encoder>
+            <pattern>%msg</pattern>
+        </encoder>
+    </appender>
+
+    <!--
+    <appender name="logfile" class="ch.qos.logback.core.FileAppender">
+        <file>${LOG_DIR}/debug.log</file>
+        <encoder>
+            <pattern>%d{yyyy-MM-dd' 'HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
+        </encoder>
+    </appender>
+    -->
+
+    <root level="DEBUG">
+        <appender-ref ref="logcat" />
+
+        <!-- in other app, detached from MainActivity.onCreate(), unless AppSettings.logfileDebugging = true -->
+        <!--
+        <appender-ref ref="logfile" />
+        -->
+    </root>
+</configuration>
--- a/app/src/main/cpp/CMakeLists.txt
+++ b/app/src/main/cpp/CMakeLists.txt
@@ -0,0 +1,48 @@
+
+# For more information about using CMake with Android Studio, read the
+# documentation: https://d.android.com/studio/projects/add-native-code.html.
+# For more examples on how to use CMake, see https://github.com/android/ndk-samples.
+
+# Sets the minimum CMake version required for this project.
+cmake_minimum_required(VERSION 3.22.1)
+
+# Declares the project name. The project name can be accessed via ${ PROJECT_NAME},
+# Since this is the top level CMakeLists.txt, the project name is also accessible
+# with ${CMAKE_PROJECT_NAME} (both CMake variables are in-sync within the top level
+# build script scope).
+project("lockstep-native")
+
+# Creates and names a library, sets it as either STATIC
+# or SHARED, and provides the relative paths to its source code.
+# You can define multiple libraries, and CMake builds them for you.
+# Gradle automatically packages shared libraries with your APK.
+#
+# In this top level CMakeLists.txt, ${CMAKE_PROJECT_NAME} is used to define
+# the target library name; in the sub-module's CMakeLists.txt, ${PROJECT_NAME}
+# is preferred for the same purpose.
+#
+# In order to load a library into your app from Java/Kotlin, you must call
+# System.loadLibrary() and pass the name of the library defined here;
+# for GameActivity/NativeActivity derived applications, the same library name must be
+# used in the AndroidManifest.xml file.
+add_library(${CMAKE_PROJECT_NAME} SHARED
+    # List C/C++ source files with relative paths to this CMakeLists.txt.
+    lockstep.cpp
+    PlaybackEngine.cpp
+)
+
+find_package (oboe REQUIRED CONFIG)
+
+add_library(ndk-logger SHARED logging.cpp logging_jni.cpp)
+target_link_libraries(ndk-logger log)
+
+# Specifies libraries CMake should link to your target library. You
+# can link libraries from various origins, such as libraries defined in this
+# build script, prebuilt third-party libraries, or Android system libraries.
+target_link_libraries(${CMAKE_PROJECT_NAME}
+    # List libraries link to the target library
+    oboe::oboe
+    android
+    log
+    ndk-logger
+)
--- a/app/src/main/cpp/OboeSinePlayer.h
+++ b/app/src/main/cpp/OboeSinePlayer.h
@@ -0,0 +1,78 @@
+//
+// Created by david on 01.02.2026.
+//
+
+#ifndef LOCKSTEP_OBOESINEPLAYER_H
+#define LOCKSTEP_OBOESINEPLAYER_H
+
+#include <oboe/Oboe.h>
+#include <math.h>
+using namespace oboe;
+
+class OboeSinePlayer: public oboe::AudioStreamDataCallback {
+public:
+
+    virtual ~OboeSinePlayer() = default;
+
+    // Call this from Activity onResume()
+    int32_t startAudio() {
+        std::lock_guard<std::mutex> lock(mLock);
+        oboe::AudioStreamBuilder builder;
+        // The builder set methods can be chained for convenience.
+        Result result = builder.setSharingMode(oboe::SharingMode::Exclusive)
+                ->setPerformanceMode(oboe::PerformanceMode::LowLatency)
+                ->setChannelCount(kChannelCount)
+                ->setSampleRate(kSampleRate)
+                ->setSampleRateConversionQuality(oboe::SampleRateConversionQuality::Medium)
+                ->setFormat(oboe::AudioFormat::Float)
+                ->setDataCallback(this)
+                ->openStream(mStream);
+        if (result != Result::OK) return (int32_t) result;
+
+        // Typically, start the stream after querying some stream information, as well as some input from the user
+        result = mStream->requestStart();
+        return (int32_t) result;
+    }
+
+    // Call this from Activity onPause()
+    void stopAudio() {
+        // Stop, close and delete in case not already closed.
+        std::lock_guard<std::mutex> lock(mLock);
+        if (mStream) {
+            mStream->stop();
+            mStream->close();
+            mStream.reset();
+        }
+    }
+
+    oboe::DataCallbackResult onAudioReady(oboe::AudioStream *oboeStream, void *audioData, int32_t numFrames) override {
+        float *floatData = (float *) audioData;
+        for (int i = 0; i < numFrames; ++i) {
+            float sampleValue = kAmplitude * sinf(mPhase);
+            for (int j = 0; j < kChannelCount; j++) {
+                floatData[i * kChannelCount + j] = sampleValue;
+            }
+            mPhase += mPhaseIncrement;
+            if (mPhase >= kTwoPi) mPhase -= kTwoPi;
+        }
+        return oboe::DataCallbackResult::Continue;
+    }
+
+private:
+    std::mutex         mLock;
+    std::shared_ptr<oboe::AudioStream> mStream;
+
+    // Stream params
+    static int constexpr kChannelCount = 2;
+    static int constexpr kSampleRate = 48000;
+    // Wave params, these could be instance variables in order to modify at runtime
+    static float constexpr kAmplitude = 0.5f;
+    static float constexpr kFrequency = 440;
+    static float constexpr kPI = M_PI;
+    static float constexpr kTwoPi = kPI * 2;
+    static double constexpr mPhaseIncrement = kFrequency * kTwoPi / (double) kSampleRate;
+    // Keeps track of where the wave is
+    float mPhase = 0.0;
+};
+
+#endif //LOCKSTEP_OBOESINEPLAYER_H
--- a/app/src/main/cpp/PlaybackEngine.cpp
+++ b/app/src/main/cpp/PlaybackEngine.cpp
@@ -0,0 +1,24 @@
+//
+// Created by david on 01.02.2026.
+//
+
+#define LOG_TAG "PlaybackEngine"
+
+#include "PlaybackEngine.h"
+#include "logging.h"
+
+PlaybackEngine::PlaybackEngine() {
+    LOGI("PlaybackEngine()");
+    LOGI("NDK LOG_LEVEL=%d", LOG_LEVEL);
+    // NDK LOG_LEVEL=3  (DEBUG)
+    mPlayer = new OboeSinePlayer();
+    int32_t res = mPlayer->startAudio();
+    LOGI("startAudio() = %d", res);
+}
+
+PlaybackEngine::~PlaybackEngine() {
+    LOGI("~PlaybackEngine()");
+    mPlayer->stopAudio();
+    delete mPlayer;
+    mPlayer = nullptr;
+}
--- a/app/src/main/cpp/PlaybackEngine.h
+++ b/app/src/main/cpp/PlaybackEngine.h
@@ -0,0 +1,18 @@
+//
+// Created by david on 01.02.2026.
+//
+
+#ifndef LOCKSTEP_PLAYBACKENGINE_H
+#define LOCKSTEP_PLAYBACKENGINE_H
+
+#include "OboeSinePlayer.h"
+
+class PlaybackEngine {
+public:
+    PlaybackEngine();
+    virtual ~PlaybackEngine();
+private:
+    OboeSinePlayer *mPlayer;
+};
+
+#endif //LOCKSTEP_PLAYBACKENGINE_H
--- a/app/src/main/cpp/lockstep.cpp
+++ b/app/src/main/cpp/lockstep.cpp
@@ -0,0 +1,54 @@
+// Write C++ code here.
+//
+// Do not forget to dynamically load the C++ library into your application.
+//
+// For instance,
+//
+// In at.lockstep.app.MainActivity.java:
+//    static {
+//       System.loadLibrary("lockstep");
+//    }
+//
+// Or, in at.lockstep.app.MainActivity.kt:
+//    companion object {
+//      init {
+//         System.loadLibrary("lockstep")
+//      }
+//    }
+
+#include "PlaybackEngine.h"
+#include <jni.h>
+#include <oboe/Oboe.h>
+
+extern "C" {
+
+/**
+ * Creates the audio engine
+ *
+ * @return a pointer to the audio engine. This should be passed to other methods
+ */
+JNIEXPORT jlong JNICALL
+Java_at_lockstep_pb_PlaybackEngine_native_1createEngine(
+        JNIEnv *env,
+        jclass /*unused*/) {
+    /*
+    const char* filesDirTemp = env->GetStringUTFChars(filesDir, NULL);
+    std::string filesDirString(filesDirTemp);
+    env->ReleaseStringUTFChars(filesDir, filesDirTemp);
+    */
+
+    // We use std::nothrow so `new` returns a nullptr if the engine creation fails
+    auto *engine = new(std::nothrow) PlaybackEngine();
+    return reinterpret_cast<jlong>(engine);
+}
+
+JNIEXPORT void JNICALL
+Java_at_lockstep_pb_PlaybackEngine_native_1deleteEngine(
+        JNIEnv *env,
+jclass,
+jlong engineHandle) {
+
+delete reinterpret_cast<PlaybackEngine *>(engineHandle);
+}
+
+} // extern "C"
--- a/app/src/main/cpp/logging.cpp
+++ b/app/src/main/cpp/logging.cpp
@@ -0,0 +1,154 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Logger implement, support writing into stdout and send for java logback
+ */
+
+#include "logging.h"
+#include <android/log.h>
+
+extern "C" {
+
+static JavaVM *		__logback_jvm = NULL;
+static jclass		__logback_jclass_logger;
+static jmethodID	__logback_jmethod_logWrite;
+
+void
+__stdout_log_print(const int level, const char * format, ...)
+{
+    va_list	args;
+    static char tags[] = {'?', '?', 'V', 'D', 'I', 'W', 'E', 'F', '?'};
+
+    va_start(args, format);
+
+    printf("[%c]%s ", tags[level], LOG_TAG);
+    vprintf(format, args);
+    printf("\n");
+
+    va_end(args);
+}
+
+void
+__stdout_log_vprint(const int level, const char * format, va_list ap)
+{
+    static char tags[] = {'?', '?', 'V', 'D', 'I', 'W', 'E', 'F', '?'};
+    printf("[%c]%s ", tags[level], LOG_TAG);
+    vprintf(format, ap);
+    printf("\n");
+}
+
+void
+__stdout_log_write(const int level, const char * msg)
+{
+    static char tags[] = {'?', '?', 'V', 'D', 'I', 'W', 'E', 'F', '?'};
+    printf("[%c]%s %s\n", tags[level], LOG_TAG, msg);
+}
+
+
+
+void
+logback_init(JavaVM * jVM, JNIEnv * env)
+{
+    __logback_jvm = jVM;
+    jclass jclass_logger = env->FindClass("com/rex/logger/NdkLogger");
+    if (! jclass_logger) {
+        __android_log_write(LOG_LEVEL_ERROR, LOG_TAG, "logback_init failed to get logger class reference");
+        return;
+    }
+    __logback_jclass_logger = (jclass) env->NewGlobalRef(jclass_logger);
+
+    __logback_jmethod_logWrite = env->GetStaticMethodID(__logback_jclass_logger, "logWrite", "(ILjava/lang/String;)V");
+    if (! __logback_jmethod_logWrite) {
+        __android_log_write(LOG_LEVEL_ERROR, LOG_TAG, "logback_init failed to get logwrite method ID");
+        return;
+    }
+}
+
+void
+logback_uninit(JNIEnv * env)
+{
+    env->DeleteGlobalRef(__logback_jclass_logger);
+    __logback_jclass_logger = NULL;
+}
+
+void
+__logback_print(const int level, const char * format, ...)
+{
+    JNIEnv *	env = NULL;
+    jint	err = JNI_OK;
+    if (! __logback_jvm) return;
+    if (JNI_EDETACHED == (err = __logback_jvm->GetEnv((void**) &env, JNI_VERSION_1_4))) {
+        if (__logback_jvm->AttachCurrentThread(&env, NULL) < 0) {
+            __android_log_write(LOG_LEVEL_WARN, LOG_TAG, "__logback_write failed to get env neither attach current thread");
+        }
+    }
+
+    static char	buffer[1024];
+    va_list args;
+    va_start(args, format);
+    vsnprintf(buffer, sizeof(buffer), format, args);
+    jstring jmsg = env->NewStringUTF(buffer);
+    env->CallStaticVoidMethod(__logback_jclass_logger, __logback_jmethod_logWrite, level, jmsg);
+    env->DeleteLocalRef(jmsg);
+    va_end(args);
+
+    if (JNI_EDETACHED == err) __logback_jvm->DetachCurrentThread();
+}
+
+void
+__logback_vprint(const int level, const char * format, va_list ap)
+{
+    JNIEnv *	env = NULL;
+    jint	err = JNI_OK;
+    if (! __logback_jvm) return;
+    if (JNI_EDETACHED == (err = __logback_jvm->GetEnv((void**) &env, JNI_VERSION_1_4))) {
+        if (__logback_jvm->AttachCurrentThread(&env, NULL) < 0) {
+            __android_log_write(LOG_LEVEL_WARN, LOG_TAG, "__logback_write failed to get env neither attach current thread");
+        }
+    }
+
+    static char	buffer[1024];
+    vsnprintf(buffer, sizeof(buffer), format, ap);
+    jstring jmsg = env->NewStringUTF(buffer);
+    env->CallStaticVoidMethod(__logback_jclass_logger, __logback_jmethod_logWrite, level, jmsg);
+    env->DeleteLocalRef(jmsg);
+
+    if (JNI_EDETACHED == err) __logback_jvm->DetachCurrentThread();
+}
+
+void
+__logback_write(const int level, const char * msg)
+{
+    JNIEnv *	env = NULL;
+    jint	err = JNI_OK;
+    if (! __logback_jvm) return;
+    if (JNI_EDETACHED == (err = __logback_jvm->GetEnv((void**) &env, JNI_VERSION_1_4))) {
+        if (__logback_jvm->AttachCurrentThread(&env, NULL) < 0) {
+            __android_log_write(LOG_LEVEL_WARN, LOG_TAG, "__logback_write failed to get env neither attach current thread");
+        }
+    }
+
+    jstring jmsg = env->NewStringUTF(msg);
+    env->CallStaticVoidMethod(__logback_jclass_logger, __logback_jmethod_logWrite, level, jmsg);
+    env->DeleteLocalRef(jmsg);
+
+    if (JNI_EDETACHED == err) __logback_jvm->DetachCurrentThread();
+}
+
+}
+
+// vim:ts=8:sw=4:
--- a/app/src/main/cpp/logging.h
+++ b/app/src/main/cpp/logging.h
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Logging support, provide the level definition and support logging to logcat, stdout and Java logback
+ * When using logback, need add com/rex/logger/NdkLogger.java into project
+ */
+
+#ifndef _LOGGING_H_
+#define _LOGGING_H_
+
+#define LOG_OUTPUT_LOGBACK
+
+#ifndef LOG_TAG
+#  define LOG_TAG	"Rex"
+#endif
+
+#ifndef LOG_LEVEL
+#  define LOG_LEVEL	LOG_LEVEL_DEBUG
+//#  define LOG_LEVEL	LOG_LEVEL_VERBOSE // note: goes to logcat only
+#endif
+
+// values here must match those in android_LogPriority
+#define	LOG_LEVEL_ALL		1
+#define	LOG_LEVEL_VERBOSE	2
+#define	LOG_LEVEL_DEBUG		3
+#define	LOG_LEVEL_INFO		4
+#define	LOG_LEVEL_WARN		5
+#define	LOG_LEVEL_ERROR		6
+#define	LOG_LEVEL_FATAL		7
+#define	LOG_LEVEL_SILENT	8
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <jni.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void __stdout_log_print(const int level, const char * format, ...);
+void __stdout_log_vprint(const int level, const char * format, va_list ap);
+void __stdout_log_write(const int level, const char * msg);
+
+void logback_init(JavaVM * jVM, JNIEnv * env);
+void logback_uninit(JNIEnv * env);
+void __logback_print(const int level, const char * format, ...);
+void __logback_vprint(const int level, const char * format, va_list ap);
+void __logback_write(const int level, const char * msg);
+
+#ifdef __cplusplus
+} //extern "C"
+#endif
+
+
+#ifdef LOG_OUTPUT_STDOUT
+#  define LOG_PRINT(prio, format, ...)	__stdout_log_print(prio, format, ##__VA_ARGS__)
+#  define LOG_VPRINT(prio, format, ap)	__stdout_log_vprint(prio, format, ap)
+#  define LOG_WRITE(prio, msg)		__stdout_log_write(prio, msg)
+#elif defined(LOG_OUTPUT_LOGBACK)
+#  define LOG_PRINT(prio, format, ...)	__logback_print(prio, LOG_TAG " - " format, ##__VA_ARGS__)
+#  define LOG_VPRINT(prio, format, ap)	__logback_vprint(prio, LOG_TAG " - " format, ap)
+#  define LOG_WRITE(prio, msg)		__logback_write(prio, LOG_TAG " - " msg)
+#  include <android/log.h>
+#  define LOG_PRINT_ANDROID(prio, format, ...)	__android_log_print(prio, LOG_TAG, format, ##__VA_ARGS__)
+#else
+#  include <android/log.h>
+#  define LOG_PRINT(prio, format, ...)	__android_log_print(prio, LOG_TAG, format, ##__VA_ARGS__)
+#  define LOG_VPRINT(prio, format, ap)	__android_log_vprint(prio, LOG_TAG, format, ap)
+#  define LOG_WRITE(prio, msg)		__android_log_write(prio, LOG_TAG, msg)
+#endif
+
+#if LOG_LEVEL > LOG_LEVEL_VERBOSE
+#  define LOGV(...)
+#else
+#  define LOGV(...)	LOG_PRINT_ANDROID(LOG_LEVEL_VERBOSE, __VA_ARGS__)
+#endif
+
+#if LOG_LEVEL > LOG_LEVEL_DEBUG
+#  define LOGD(...)
+#else
+#  define LOGD(...)	LOG_PRINT(LOG_LEVEL_DEBUG, __VA_ARGS__)
+#endif
+
+#if LOG_LEVEL > LOG_LEVEL_INFO
+#  define LOGI(...)
+#else
+#  define LOGI(...)	LOG_PRINT(LOG_LEVEL_INFO, __VA_ARGS__)
+#endif
+
+#if LOG_LEVEL > LOG_LEVEL_WARN
+#  define LOGW(...)
+#else
+#  define LOGW(...)	LOG_PRINT(LOG_LEVEL_WARN, __VA_ARGS__)
+#endif
+
+#if LOG_LEVEL > LOG_LEVEL_ERROR
+#  define LOGE(...)
+#else
+#  define LOGE(...)	LOG_PRINT(LOG_LEVEL_ERROR, __VA_ARGS__)
+#endif
+
+
+#endif /* #ifndef _LOGGING_H_ */
+
+// vim:ts=8:sw=4:
--- a/app/src/main/cpp/logging_jni.cpp
+++ b/app/src/main/cpp/logging_jni.cpp
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <string.h>
+#include <jni.h>
+
+#include "logging.h"
+
+
+extern "C" jstring
+Java_com_rex_logger_NdkLogger_native_1getABI(JNIEnv* env, jclass thiz)
+{
+#if defined(__arm__)
+    #if defined(__ARM_ARCH_7A__)
+    #if defined(__ARM_NEON__)
+      #if defined(__ARM_PCS_VFP)
+        #define ABI "armeabi-v7a/NEON (hard-float)"
+      #else
+        #define ABI "armeabi-v7a/NEON"
+      #endif
+    #else
+      #if defined(__ARM_PCS_VFP)
+        #define ABI "armeabi-v7a (hard-float)"
+      #else
+        #define ABI "armeabi-v7a"
+      #endif
+    #endif
+  #else
+   #define ABI "armeabi"
+  #endif
+#elif defined(__i386__)
+#define ABI "x86"
+#elif defined(__x86_64__)
+#define ABI "x86_64"
+#elif defined(__mips64)  /* mips64el-* toolchain defines __mips__ too */
+#define ABI "mips64"
+#elif defined(__mips__)
+#define ABI "mips"
+#elif defined(__aarch64__)
+#define ABI "arm64-v8a"
+#else
+#define ABI "unknown"
+#endif
+
+    return env->NewStringUTF(ABI);
+}
+
+extern "C" jint
+JNI_OnLoad(JavaVM * vm, void * reserved)
+{
+    JNIEnv *	env	= NULL;
+    jclass	clazz;
+    //LOGV("JNI_Onload vm:%p reserved:%p", vm, reserved);
+
+    if (JNI_OK != vm->GetEnv((void**) &env, JNI_VERSION_1_4)) {
+        //LOGE("JNI_OnUnload GetEnv JNI_VERSION_1_4 failed");
+        return JNI_VERSION_1_4;
+    }
+
+    logback_init(vm, env);
+
+    return JNI_VERSION_1_4;
+}
+
+extern "C" void
+JNI_OnUnload(JavaVM * vm, void * reserved)
+{
+    JNIEnv *    env     = NULL;
+    //LOGV("JNI_OnUnload vm:%p reserved:%p", vm, reserved);
+
+    if (JNI_OK != vm->GetEnv((void**) &env, JNI_VERSION_1_4)) {
+        //LOGE("JNI_OnUnload GetEnv JNI_VERSION_1_4 failed");
+        return;
+    }
+
+    logback_uninit(env);
+}
+
+// vim:ts=8:sw=4:
--- a/app/src/main/java/at/lockstep/app/MainActivity.java
+++ b/app/src/main/java/at/lockstep/app/MainActivity.java
@@ -0,0 +1,23 @@
+package at.lockstep.app;
+
+import android.app.Activity;
+
+import at.lockstep.pb.PlaybackEngine;
+
+public class MainActivity extends Activity {
+    /*
+     * Creating engine in onResume() and destroying in onPause() so the stream retains exclusive
+     * mode only while in focus. This allows other apps to reclaim exclusive stream mode.
+     */
+    @Override
+    protected void onResume() {
+        super.onResume();
+        PlaybackEngine.create(this); // note: called twice (is permission request causing Activity to go out of focus?)
+    }
+
+    @Override
+    protected void onPause() {
+        PlaybackEngine.delete();
+        super.onPause();
+    }
+}
--- a/app/src/main/java/at/lockstep/pb/PlaybackEngine.java
+++ b/app/src/main/java/at/lockstep/pb/PlaybackEngine.java
@@ -0,0 +1,31 @@
+package at.lockstep.pb;
+
+import android.content.Context;
+import android.util.Log;
+
+public class PlaybackEngine {
+    static long mEngineHandle = 0;
+
+    static {
+        System.loadLibrary("lockstep-native");
+    }
+
+    public static boolean create(Context context) {
+        if (mEngineHandle == 0) {
+            //setDefaultStreamValues(context); // TODO
+            Log.i("PlaybackEngine", "Hello PlaybackEngine");
+            mEngineHandle = native_createEngine();
+        }
+        return (mEngineHandle != 0);
+    }
+
+    public static void delete() {
+        if (mEngineHandle != 0){
+            native_deleteEngine(mEngineHandle);
+        }
+        mEngineHandle = 0;
+    }
+
+    private static native long native_createEngine();
+    private static native void native_deleteEngine(long engineHandle);
+}
--- a/app/src/main/java/com/rex/logger/NdkLogger.java
+++ b/app/src/main/java/com/rex/logger/NdkLogger.java
@@ -0,0 +1,68 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You under the Apache License, Version 2.0
+ *  (the "License"); you may not use this file except in compliance with
+ *  the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+package com.rex.logger;
+
+import android.util.Log;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+//import proguard.annotation.KeepName;
+
+//@KeepName
+
+/**
+ * Gather native log into logback, for easy control save log into SDCard
+ */
+public class NdkLogger {
+
+    private static final Logger sLogger = LoggerFactory.getLogger("NDK");
+
+    //@KeepName
+    public static void logWrite(int level, String message) {
+        //sLogger.trace("level:{} message:{}", level, message);
+        switch (level) {
+            case Log.VERBOSE:
+                sLogger.trace(message);
+                break;
+            case Log.DEBUG:
+                sLogger.debug(message);
+                break;
+            case Log.INFO:
+                sLogger.info(message);
+                break;
+            case Log.WARN:
+                sLogger.warn(message);
+                break;
+            case Log.ERROR:
+                sLogger.error(message);
+                break;
+        }
+    }
+
+    static {
+        try {
+            System.loadLibrary("ndk-logger");
+        } catch (UnsatisfiedLinkError ex) {
+            sLogger.error("Failed to load library.", ex);
+        }
+    }
+
+    public static String getABI() { return native_getABI(); }
+    private static native String native_getABI();
+}
--- a/app/src/main/res/drawable/ic_launcher_background.xml
+++ b/app/src/main/res/drawable/ic_launcher_background.xml
@@ -0,0 +1,170 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillColor="#3DDC84"
+        android:pathData="M0,0h108v108h-108z" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M9,0L9,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,0L19,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,0L29,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,0L39,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,0L49,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,0L59,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,0L69,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,0L79,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M89,0L89,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M99,0L99,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,9L108,9"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,19L108,19"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,29L108,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,39L108,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,49L108,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,59L108,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,69L108,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,79L108,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,89L108,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,99L108,99"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,29L89,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,39L89,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,49L89,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,59L89,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,69L89,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,79L89,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,19L29,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,19L39,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,19L49,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,19L59,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,19L69,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,19L79,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+</vector>
--- a/app/src/main/res/drawable/ic_launcher_foreground.xml
+++ b/app/src/main/res/drawable/ic_launcher_foreground.xml
@@ -0,0 +1,30 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path android:pathData="M31,63.928c0,0 6.4,-11 12.1,-13.1c7.2,-2.6 26,-1.4 26,-1.4l38.1,38.1L107,108.928l-32,-1L31,63.928z">
+        <aapt:attr name="android:fillColor">
+            <gradient
+                android:endX="85.84757"
+                android:endY="92.4963"
+                android:startX="42.9492"
+                android:startY="49.59793"
+                android:type="linear">
+                <item
+                    android:color="#44000000"
+                    android:offset="0.0" />
+                <item
+                    android:color="#00000000"
+                    android:offset="1.0" />
+            </gradient>
+        </aapt:attr>
+    </path>
+    <path
+        android:fillColor="#FFFFFF"
+        android:fillType="nonZero"
+        android:pathData="M65.3,45.828l3.8,-6.6c0.2,-0.4 0.1,-0.9 -0.3,-1.1c-0.4,-0.2 -0.9,-0.1 -1.1,0.3l-3.9,6.7c-6.3,-2.8 -13.4,-2.8 -19.7,0l-3.9,-6.7c-0.2,-0.4 -0.7,-0.5 -1.1,-0.3C38.8,38.328 38.7,38.828 38.9,39.228l3.8,6.6C36.2,49.428 31.7,56.028 31,63.928h46C76.3,56.028 71.8,49.428 65.3,45.828zM43.4,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2c-0.3,-0.7 -0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C45.3,56.528 44.5,57.328 43.4,57.328L43.4,57.328zM64.6,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2s-0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C66.5,56.528 65.6,57.328 64.6,57.328L64.6,57.328z"
+        android:strokeWidth="1"
+        android:strokeColor="#00000000" />
+</vector>
--- a/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml
+++ b/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+    <monochrome android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>
--- a/app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml
+++ b/app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+    <monochrome android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>
--- a/app/src/main/res/mipmap-hdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-hdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-hdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-hdpi/ic_launcher_round.webp
--- a/app/src/main/res/mipmap-mdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-mdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-mdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-mdpi/ic_launcher_round.webp
--- a/app/src/main/res/mipmap-xhdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-xhdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-xhdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-xhdpi/ic_launcher_round.webp
--- a/app/src/main/res/mipmap-xxhdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-xxhdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-xxhdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-xxhdpi/ic_launcher_round.webp
--- a/app/src/main/res/mipmap-xxxhdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-xxxhdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-xxxhdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-xxxhdpi/ic_launcher_round.webp
--- a/app/src/main/res/values/colors.xml
+++ b/app/src/main/res/values/colors.xml
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="purple_200">#FFBB86FC</color>
+    <color name="purple_500">#FF6200EE</color>
+    <color name="purple_700">#FF3700B3</color>
+    <color name="teal_200">#FF03DAC5</color>
+    <color name="teal_700">#FF018786</color>
+    <color name="black">#FF000000</color>
+    <color name="white">#FFFFFFFF</color>
+</resources>
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -0,0 +1,3 @@
+<resources>
+    <string name="app_name">Lockstep</string>
+</resources>
--- a/app/src/main/res/values/themes.xml
+++ b/app/src/main/res/values/themes.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <style name="Theme.Lockstep" parent="android:Theme.Material.Light.NoActionBar" />
+</resources>
--- a/app/src/main/res/xml/backup_rules.xml
+++ b/app/src/main/res/xml/backup_rules.xml
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+   Sample backup rules file; uncomment and customize as necessary.
+   See https://developer.android.com/guide/topics/data/autobackup
+   for details.
+   Note: This file is ignored for devices older that API 31
+   See https://developer.android.com/about/versions/12/backup-restore
+-->
+<full-backup-content>
+    <!--
+   <include domain="sharedpref" path="."/>
+   <exclude domain="sharedpref" path="device.xml"/>
+-->
+</full-backup-content>
--- a/app/src/main/res/xml/data_extraction_rules.xml
+++ b/app/src/main/res/xml/data_extraction_rules.xml
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+   Sample data extraction rules file; uncomment and customize as necessary.
+   See https://developer.android.com/about/versions/12/backup-restore#xml-changes
+   for details.
+-->
+<data-extraction-rules>
+    <cloud-backup>
+        <!-- TODO: Use <include> and <exclude> to control what is backed up.
+        <include .../>
+        <exclude .../>
+        -->
+    </cloud-backup>
+    <!--
+    <device-transfer>
+        <include .../>
+        <exclude .../>
+    </device-transfer>
+    -->
+</data-extraction-rules>