本文是在ffmpeg的編譯完成的基礎(chǔ)上用cmake對(duì)ffmpeg的so庫(kù)進(jìn)行調(diào)用

具體步驟

一、創(chuàng)建一個(gè)包含c++的項(xiàng)目

創(chuàng)建新項(xiàng)目的時(shí)候，記得勾選include c++ support，項(xiàng)目中會(huì)在main目錄下自動(dòng)創(chuàng)建cpp目錄并生成一個(gè)現(xiàn)成的cpp文件。

二、將生成的so庫(kù)和頭文件拷貝進(jìn)項(xiàng)目中

image.png

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效果如下：

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三、配置CMakeLists.txt 文件（CMake構(gòu)建腳本）

具體在CMakeLists中添加的Cmake命令用法，請(qǐng)參考這篇文章
需要注意的是CMakelists的位置，CMAKE_SOURCE_DIR就代表CMakeLists所在的路徑。我的項(xiàng)目中CMakeLists的路徑是與build.gradle同級(jí)的

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# For more information about using CMake with Android Studio, read the
cmake_minimum_required(VERSION 3.4.1)

set(lib_src_DIR ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI})

message("CURRENT_DIR:" ${CMAKE_SOURCE_DIR})
##添加一個(gè)庫(kù)
add_library( # Sets the name of the library.
        native-lib

        # Sets the library as a shared library.
        SHARED

        # Provides a relative path to your source file(s).
        ${CMAKE_SOURCE_DIR}/src/main/cpp/native-lib.cpp)
add_library(avcodec-57 SHARED IMPORTED)
add_library(avformat-57 SHARED IMPORTED)
add_library(avutil-55 SHARED IMPORTED)
add_library(swresample-2 SHARED IMPORTED)
add_library(swscale-4 SHARED IMPORTED)

set_target_properties(avcodec-57 PROPERTIES IMPORTED_LOCATION
        ${lib_src_DIR}/libavcodec-57.so)
set_target_properties(avformat-57 PROPERTIES IMPORTED_LOCATION
        ${lib_src_DIR}/libavformat-57.so)
set_target_properties(avutil-55 PROPERTIES IMPORTED_LOCATION
        ${lib_src_DIR}/libavutil-55.so)
set_target_properties(swresample-2 PROPERTIES IMPORTED_LOCATION
        ${lib_src_DIR}/libswresample-2.so)
set_target_properties(swscale-4 PROPERTIES IMPORTED_LOCATION
        ${lib_src_DIR}/libswscale-4.so)

include_directories(${CMAKE_SOURCE_DIR}/src/main/cpp/include)
#找到log庫(kù)
find_library( # Sets the name of the path variable.
        log-lib

        log)
##給目標(biāo)庫(kù)添加依賴庫(kù)
target_link_libraries(
        native-lib#目標(biāo)庫(kù)

        # 依賴庫(kù)，可以寫多個(gè)
        ${log-lib}
        avcodec-57
        avformat-57
        avutil-55
        swresample-2
        swscale-4)

Androidstudio最新版好像創(chuàng)建完c++后自動(dòng)生成的CMakeLists是在cpp目錄下的，這個(gè)CMakeLists在哪都行，不過千萬要記住修改幾處調(diào)用CMakeLists路徑的地方。有以下幾處：
1、CMakeLists中用到CMAKE_SOURCE_DIR的地方

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2、build.gradle中

image.png

四、編寫 C++代碼

include/libavcodec/avcodec.h是引用的so庫(kù)的頭文件，需要注意使用extern "C"包裹起來

#include <jni.h>
#include <string>

extern "C" {
#include "include/libavcodec/avcodec.h"
}
extern "C" JNIEXPORT jstring JNICALL
Java_com_face_jfshare_nativetest_MainActivity_stringFromJNI(
        JNIEnv *env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}
extern "C"
JNIEXPORT jstring JNICALL
Java_com_face_jfshare_nativetest_MainActivity_stringTest(JNIEnv *env,
                                                         jobject /* this */) {
    char info[10000] = {0};
    sprintf(info, "%s\n", avcodec_configuration());
    return env->NewStringUTF(info);
}

五、調(diào)用本地代碼

public class MainActivity extends AppCompatActivity {

    // Used to load the 'native-lib' library on application startup.
    static {
        System.loadLibrary("native-lib");
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Example of a call to a native method
        TextView tv = findViewById(R.id.sample_text);
        tv.setText(stringTest());
    }

    /**
     * A native method that is implemented by the 'native-lib' native library,
     * which is packaged with this application.
     */
    public native String stringFromJNI();
    public native String stringTest();
}

六、運(yùn)行app

56895DA6D4025A63FAF295CED96F3C2F.jpg

注意事項(xiàng)

1：由于我生成的ffmpeg僅僅支持armeabi和armeabi-v7a所以在build.gradle中需要注意只能匹配armeabi-v7a（高版本ndk不允許匹配armeabi）

    ndk{
            abiFilters "armeabi-v7a"
        }

參考鏈接：
1、https://www.cnblogs.com/fnlingnzb-learner/p/7593488.html
2、http://www.itdecent.cn/p/a1fe55d5683b