What is the equivalent of target_link_libraries in Android.mk

Question

I am trying to compile an android project using Android.mk and need to include the following libraries: native-audio-jni android log OpenSLES. A similar project (https://github.com/googlesamples/android-ndk/tree/master/native-audio), which includes the same libraries but uses CMakeLists.txt instead of Android.mk has this line in the CMakeLists.txt:

target_link_libraries(native-audio-jni android log OpenSLES)

This sample project builds and runs fine.

Based on findings from my online research on the topic, I have tried including the following lines in my Android.mk file, which is in the jni folder:

LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog -lOpenSLES -lnative-audio-jni
LOCAL_LDLIBS    += -landroid
ldLibs = ["android", "log", "native-audio-jni", "OpenSLES"]
LOCAL_SHARED_LIBRARIES += libandroid
LOCAL_LDLIBS := -llog

However, I still get errors like:

undefined reference to `AAssetManager_fromJava'
undefined reference to `AAssetManager_open'
undefined reference to `SL_IID_SEEK'
undefined reference to `SL_IID_MUTESOLO' ...

I also have the following includes in my .c file where the errors are generated:

// for native audio
#include <SLES/OpenSLES.h>
#include <SLES/OpenSLES_Android.h>

// for native asset manager
#include <sys/types.h>
#include <android/asset_manager.h>
#include <android/asset_manager_jni.h>
#include <android/log.h>

So my question is: How to add these libraries to my Android.mk or in other words: What is the equivalent of target_link_libraries(native-audio-jni android log OpenSLES) in Android.mk? For a number of reasons I need to use Android.mk instead of CMakeLists.txt in my project.

Here also is my build.gradle if this is of any help:

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-android'

android {
compileSdkVersion 27

defaultConfig {
        applicationId "com.google.ar.sceneform.samples.drawing"

    // 24 is the minimum since ARCore only works with 24 and higher.
    minSdkVersion 24
    targetSdkVersion 27
    versionCode 1
    versionName "1.0"
    ndk {
        //ldLibs "android", "log", "native-audio-jni", "OpenSLES" // Not helping
        /*
         * Sceneform is available for the following ABIs: arm64-v8a, armv7a,
         * x86_64 and x86. This sample app enables arm64-v8a to run on
         * devices and x86 to run on the emulator. Your application should
         * list the ABIs most appropriate to minimize APK size (arm64-v8a recommended).
         */
        abiFilters 'arm64-v8a' ,'x86' // , 'armeabi-v7a'
    }
}
compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}

externalNativeBuild {
    ndkBuild {
        path '../jni/Android.mk'
    }
}

    lintOptions {
        abortOnError false
    }
}

dependencies {
    //implementation fileTree(dir: 'libs', include: ['*.jar']) // NOT helping
    implementation 'com.google.ar.sceneform.ux:sceneform-ux:1.7.0'
    implementation 'com.android.support:appcompat-v7:27.1.1'
    implementation 'com.android.support:design:27.1.1'
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation files('Libs/YouTubeAndroidPlayerApi.jar')
    implementation 'com.github.barteksc:android-pdf-viewer:2.0.3'
    implementation 'com.xw.repo:bubbleseekbar:3.19-lite'
}
repositories {
    mavenCentral()
}

apply plugin: 'com.google.ar.sceneform.plugin'

sceneform.asset('sampledata/models/andy.obj',
        'default',
        'sampledata/models/andy.sfa',
        'src/main/res/raw/andy')

And my Android.mk file:

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

include $(CLEAR_VARS)
LOCAL_MODULE := aubio
LOCAL_SRC_FILES := $(TARGET_ARCH_ABI)/libaubio.so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := pitch
LOCAL_SRC_FILES := pitch.c
LOCAL_SHARED_LIBRARIES := aubio
include $(BUILD_SHARED_LIBRARY)

LOCAL_LDLIBS := -llog -lOpenSLES -lnative-audio-jni -landroid

An this is a screenshot of the built error: enter image description here

Answer 1

Your Android.mk got some unnecessary definitions that ruin happen to hide he correct one:

LOCAL_LDLIBS := -llog -lOpenSLES -lnative-audio-jni -landroid

instead of all the lines that you posted. NDK knows where to find these libraries, therefore -L$(SYSROOT)/… is not necessary, but only can hurt. The other lines probably come from frustration.