Multi tool use

No implementation found for native code in android

Now Im using ffmpeg java library in android. I want to use it directly in my app, So Im inporting this library. But I have a problem with it.

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.softcode.kihnoplay, PID: 15313
java.lang.UnsatisfiedLinkError: No implementation found for java.lang.String androidFfmpeg.ArmArchHelper.cpuArchFromJNI() (tried Java_androidFfmpeg_ArmArchHelper_cpuArchFromJNI and Java_androidFfmpeg_ArmArchHelper_cpuArchFromJNI__)
at androidFfmpeg.ArmArchHelper.cpuArchFromJNI(Native Method)
at androidFfmpeg.CpuArchHelper.getCpuArch(CpuArchHelper.java:16)
at androidFfmpeg.FFmpeg.loadBinary(FFmpeg.java:40)
at com.softcode.tablet.Mp3Concat_Thread.startThread(Mp3Concat_Thread.java:90)
at com.softcode.tablet.Mp3Concat_Thread.<init>(Mp3Concat_Thread.java:54)
at com.softcode.phone.record.view.RecordActivity.onCreate(RecordActivity.java:182)
at android.app.Activity.performCreate(Activity.java:6955)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1126)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2927)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3045)
at android.app.ActivityThread.-wrap14(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1642)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6776)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1520)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1410)


I don't know why this error is occurring.

My directory tree is

and c file code.

#include <jni.h>
#include <stdio.h>
#include <stdlib.h>
#include <cpu-features.h>

jstring
Java_androidFfmpeg_ArmArchHelper_cpuArchFromJNI(JNIEnv* env, jobject obj)
{
char arch_info[11] = "";

if (android_getCpuFamily() == ANDROID_CPU_FAMILY_ARM) {
strcpy(arch_info, "ARM");

uint64_t cpuFeatures = android_getCpuFeatures();
if ((cpuFeatures & ANDROID_CPU_ARM_FEATURE_ARMv7) != 0) {
strcat(arch_info, " v7");

if((cpuFeatures & ANDROID_CPU_ARM_FEATURE_NEON) != 0) {
strcat(arch_info, "-neon");
}
}
}
return (*env)->NewStringUTF(env, arch_info);
}


And this is a grade(app)

android {
compileSdkVersion 27
buildToolsVersion '27.0.3'
defaultConfig {
applicationId "com.softcode.kihnoplay"
minSdkVersion 21
targetSdkVersion 25
versionCode 1
versionName "1.00"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

renderscriptTargetApi 19
renderscriptSupportModeEnabled true

ndk {
abiFilters "armeabi", "armeabi-v7a","x86"
}

aaptOptions
{
cruncherEnabled = false
}
}

buildTypes {
debug {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
sourceSets.main {
jniLibs.srcDir 'src/main/libs'
jni.srcDirs = //important!!!! disable automatic ndk-build call
}


I don't know why this error is occurring. If you know this problem please let me know. Thanks you!

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

1 Answer
1

I guess you are using a clang++ compiling c source code, right? If true, try to change your file name to be armArch.cpp and add keyword extern into your C header and source files. e.g.

#ifdef __cplusplus
extern "C" {
#endif

// your function declarations or implementations.

#ifdef __cplusplus
}
#endif


Also, i would like to suggest use externalNativeBuild and cmake block rather than the older ndk block which is not the modern convention for Android native builds. E.g.

android {

//....

defaultConfig {
applicationId "com.softcode.kihnoplay"
minSdkVersion 21
targetSdkVersion 25
versionCode 1
versionName "1.00"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

externalNativeBuild {
cmake {
cppFlags "-std=c++11 -frtti -fexceptions"
abiFilters 'armeabi-v7a', 'arm64-v8a', 'x86', 'x86_64'
}
}
}
buildTypes {
release {
//....
}
}

externalNativeBuild {
cmake {
path "CMakeLists.txt"
}
}
}


Android NDK has deprecated armeabi, you don't actually need to include this ABI is your abiFilters setting. ABIs 'armeabi-v7a', 'arm64-v8a', 'x86', 'x86_64' will be enough for supporting almost all the current Android devices as well as emulators.

You can find a comprehensive JNI tutorial from https://arophix.com/2017/12/17/andoid-jni-summary/
and a sample JNI project from https://github.com/russell-shizhen/JniExample

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