之前一直在linux下编译FFmpeg，最近换电脑了，尝试了下在mac下编译ffmpeg,特记录之。
一. 准备工作
1. 下载FFmpeg。(http://ffmpeg.org/download.html#releases)，看了下最新的是4.1.4，我用的是3.4.6。
2. 下载mac上使用的NDK。(https://developer.android.google.cn/ndk/downloads/index.html), 我用的是android-ndk-r14b-darwin-x86_64.zip，不推荐使用ndk-bundle,有些头文件在ndk-bundle里没有，遇到过一次。
3. 修改FFmpeg3.4.6目录下的configure文件。如果不修改的话之后编译生成的版本号会加在so的后面，会导致android不能识别，切记。
修改的内容如下，将：
SLIBNAME_WITH_MAJOR='$(SLIBNAME).$(LIBMAJOR)' LIB_INSTALL_EXTRA_CMD='$$(RANLIB)"$(LIBDIR)/$(LIBNAME)"' SLIB_INSTALL_NAME='$(SLIBNAME_WITH_VERSION)' SLIB_INSTALL_LINKS='$(SLIBNAME_WITH_MAJOR)$(SLIBNAME)'
修改成：
SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(FULLNAME)-$(LIBMAJOR)$(SLIBSUF)' LIB_INSTALL_EXTRA_CMD='$$(RANLIB)"$(LIBDIR)/$(LIBNAME)"' SLIB_INSTALL_NAME='$(SLIBNAME_WITH_MAJOR)' SLIB_INSTALL_LINKS='$(SLIBNAME)'
4. 编写编译用的脚本文件。这个网上有很多，我找到了两个可以用的：
用于编译 armeabi-v7a、arm64-v8a、x86_64版本的：
#!/bin/bash echo "进入FFmpeg编译脚本" # NDK环境 export NDK=/Users/haiyuegao/Library/Android/android-ndk-r14b export SYSROOT=$NDK/platforms/android-21/arch-arm export TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64 PREFIX=android-build COMMON_OPTIONS=" --prefix=android/ --target-os=android --enable-shared --enable-runtime-cpudetect --enable-small --disable-static --disable-debug --disable-ffmpeg --disable-ffplay --disable-ffprobe --disable-ffserver --disable-doc --disable-symver --disable-asm --disable-stripping --disable-armv5te " function build_android { echo "开始编译FFmpeg..." # armeabi echo "开始编译FFmpeg(armeabi)" ./configure --libdir=${PREFIX}/libs/armeabi --incdir=${PREFIX}/include/armeabi --pkgconfigdir=${PREFIX}/pkgconfig/armeabi --arch=arm --cpu=armv6 --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- --sysroot=$SYSROOT --extra-ldexeflags=-pie ${COMMON_OPTIONS} make clean make -j8 && make install echo "结束编译FFmpeg(armeabi)" # armeabi-v7a echo "开始编译FFmpeg(armeabi-v7a)" ./configure --libdir=${PREFIX}/libs/armeabi-v7a --incdir=${PREFIX}/include/armeabi-v7a --pkgconfigdir=${PREFIX}/pkgconfig/armeabi-v7a --arch=arm --cpu=armv7-a --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- --sysroot=$SYSROOT --extra-cflags="-march=armv7-a -mfloat-abi=softfp -mfpu=neon" --extra-ldexeflags=-pie ${COMMON_OPTIONS} make clean make -j8 && make install echo "结束编译FFmpeg(armeabi-v7a)" # arm64-v8a echo "开始编译FFmpeg(arm64-v8a)" ./configure --libdir=${PREFIX}/libs/arm64-v8a --incdir=${PREFIX}/include/arm64-v8a --pkgconfigdir=${PREFIX}/pkgconfig/arm64-v8a --arch=aarch64 --cpu=armv8-a --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- --sysroot=$SYSROOT --extra-ldexeflags=-pie ${COMMON_OPTIONS} make clean make -j8 && make install echo "结束编译FFmpeg(arm64-v8a)" # x86_64 echo "开始编译FFmpeg(x86_64)" ./configure --libdir=${PREFIX}/libs/x86_64 --incdir=${PREFIX}/include/x86_64 --pkgconfigdir=${PREFIX}/pkgconfig/x86_64 --arch=x86_64 --cpu=x86_64 --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- --sysroot=$SYSROOT --extra-ldexeflags=-pie ${COMMON_OPTIONS} make clean make -j8 && make install echo "结束编译FFmpeg(x86_64)" echo "编译结束" }; build_android
用于编译x86版本的
#!/bin/bash echo "进入FFmpeg编译脚本" # NDK环境 export NDK=/Users/haiyuegao/Library/Android/android-ndk-r14b export SYSROOT=$NDK/platforms/android-21/arch-x86 export TOOLCHAIN=$NDK/toolchains/x86-4.9/prebuilt/darwin-x86_64 PREFIX=android-build COMMON_OPTIONS=" --prefix=android/ --target-os=android --enable-shared --enable-runtime-cpudetect --enable-small --disable-static --disable-debug --disable-ffmpeg --disable-ffplay --disable-ffprobe --disable-ffserver --disable-doc --disable-symver --disable-asm --disable-stripping --disable-armv5te " function build_android { echo "开始编译FFmpeg..." # x86 echo "开始编译FFmpeg(x86)" ./configure --libdir=${PREFIX}/libs/x86 --incdir=${PREFIX}/include/x86 --pkgconfigdir=${PREFIX}/pkgconfig/x86 --arch=x86 --cpu=i686 --cross-prefix=$TOOLCHAIN/bin/i686-linux-android- --sysroot=$SYSROOT --extra-cflags="-Os -fpic -march=i686 -mtune=intel -mssse3 -mfpmath=sse -m32" --extra-ldexeflags=-pie ${COMMON_OPTIONS} make clean make -j8 && make install echo "结束编译FFmpeg(x86)" echo "编译结束" }; build_android
需要注意的是：要根据自己电脑的实际环境修改下上面的NDK目录地址，我的NDK地址是：
5. 修改脚本的执行权限。将脚本放置到ffmpeg的根目录下，为其添加执行权限：
然后打开终端，cd到ffmpeg那级目录，分别执行以下两条命令（如果要编译x86版本，就把shell脚本的名字换成x86版本的那个）：
chmod 777 macos_build_android.sh ./macos_build_android.sh
6. 开始编译。视电脑的配置不同编译的时间也不同，我电脑用了大约5分钟左右完成了编译。
等待编译完成，稍后ffmpeg那级目录会出现一个android-build文件夹，里面包含了我们会用到的库文件和头文件。
二. 集成FFmpeg到项目中
1. 新建一个支持C++的Android Studio 项目。
2. 拷贝ffmpeg库文件和头文件。将编译生成的libs文件夹和include文件夹分别拷贝到项目的app目录下：
3. 更新配置文件。
修改app目录下的build.gradle文件：
添加下列代码到gradle文件:
externalNativeBuild { cmake { cppFlags "-std=c++11" } ndk { abiFilters "armeabi-v7a","x86" } } sourceSets { main { jniLibs.srcDirs=['libs'] } }
externalNativeBuild { cmake { path "CMakeLists.txt" } }
最终文件如下：
apply plugin: 'com.android.application' android { compileSdkVersion 28 defaultConfig { applicationId "com.yongdaimi.android.ffapitest" minSdkVersion 19 targetSdkVersion 28 versionCode 1 versionName "1.0" testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" externalNativeBuild { cmake { cppFlags "-std=c++11" } ndk { abiFilters "armeabi-v7a","x86" } } sourceSets { main { jniLibs.srcDirs=['libs'] } } } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro' } } externalNativeBuild { cmake { path "CMakeLists.txt" } } } dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation 'com.android.support:appcompat-v7:28.0.0' implementation 'com.android.support.constraint:constraint-layout:1.1.3' testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.2' androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2' }
修改app目录下的CMakeLists.txt文件：
# For more information about using CMake with Android Studio, read the # documentation: https://d.android.com/studio/projects/add-native-code.html # Sets the minimum version of CMake required to build the native library. cmake_minimum_required(VERSION 3.4.1) # 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. # 添加头文件路径 include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include/${ANDROID_ABI}) # 设置FFmpeg库所在路径 set(FF ${CMAKE_CURRENT_SOURCE_DIR}/libs/${ANDROID_ABI}) # 打印当前位置信息 message("Current souce file positon: " ${CMAKE_CURRENT_SOURCE_DIR}) # avcodec add_library(avcodec SHARED IMPORTED) set_target_properties(avcodec PROPERTIES IMPORTED_LOCATION ${FF}/libavcodec.so) 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). src/main/cpp/native-lib.cpp) # Searches for a specified prebuilt library and stores the path as a # variable. Because CMake includes system libraries in the search path by # default, you only need to specify the name of the public NDK library # you want to add. CMake verifies that the library exists before # completing its build. find_library( # Sets the name of the path variable. log-lib # Specifies the name of the NDK library that # you want CMake to locate. log) # Specifies libraries CMake should link to your target library. You # can link multiple libraries, such as libraries you define in this # build script, prebuilt third-party libraries, or system libraries. target_link_libraries( # Specifies the target library. native-lib avcodec # Links the target library to the log library # included in the NDK. ${log-lib})
最终目录结构如下：
这里一定要注意CMakeLists.txt这个文件的位置，我在Windows下创建AS项目时这个文件在app目录下，在Mac上创建AS项目时这个文件却在app/src/main/cpp目录下，个人为了保持习惯，便将这个文件仍然移动到了app目录下，若使用Mac上默认的位置，则上述CMakeLists.txt和build.gradle中声明文件的位置部分也需要修改，切记。
4. 添加测试代码。打开native-lib.cpp,修改已有的JNI方法：
#include <jni.h> #include <string> extern "C" { #include <libavcodec/avcodec.h> } extern "C" JNIEXPORT jstring JNICALL Java_com_yongdaimi_android_ffapitest_MainActivity_stringFromJNI( JNIEnv *env, jobject /* this */) { std::string hello = "Hello from C++"; hello += avcodec_configuration(); return env->NewStringUTF(hello.c_str()); }
由于FFmpeg是使用纯C编写的，因此在导入其头文件的时候要注意使用extern "C" 大括号包裹。
之后运行项目，如果能出现相关的配置信息就说明FFmpeg已经加载成功了。
三. 常见错误说明
1. Error computing CMake server result.
若编译出现
Error computing CMake server result. Check for working C compiler: D:/sdk/sdk/ndk-bundle/toolchains/llvm/prebuilt/windows-x86_64/bin/clang.exe Check for working C compiler: D:/sdk/sdk/ndk-bundle/toolchains/llvm/prebuilt/windows-x86_64/bin/clang.exe -- works Detecting C compiler ABI info Detecting C compiler ABI info - done Detecting C compile features Detecting C compile features - done Check for working CXX compiler: D:/sdk/sdk/ndk-bundle/toolchains/llvm/prebuilt/windows-x86_64/bin/clang++.exe Check for working CXX compiler: D:/sdk/sdk/ndk-bundle/toolchains/llvm/prebuilt/windows-x86_64/bin/clang++.exe -- works Detecting CXX compiler ABI info Detecting CXX compiler ABI info - done Detecting CXX compile features Detecting CXX compile features - done Boost version: 1.70.0 Configuring for JNI Configuring done
则打开Build的Toggle View按钮，根据Log分析出错的详细原因，看看是native-lib.cpp的文件找不到或者是其它问题。
2. ninja error needed by missing and no known rule to make it
Error:error: '../../../../src/main/jniLibs/x86/libstblur_preview_api.so',
needed by '../../../../build/intermediates/cmake/debug/obj/x86/libjnistblur_preview_api.so', missing and no known rule to make it
这种错误一般是缺失了某个平台的库导致的，首先查看具体缺失的是哪个平台的so库，如果该平台的库不需要，可以在app下的build.gradle中声明不加载：
ndk { // 声明只使用这两个版本的库,否则默认的可是4个平台 abiFilters 'armeabi-v7a','arm64-v8a' }
或者是检查下CMakeLists.txt中FFmpeg库的路径声明是否正确：
比如我这里声明的库路径就是app/libs/具体的平台。
参考链接：