FFmpeg编译为so库导入安卓开发

本文主要阐述如何获取ffmpeg源码并进行交叉编译，并编译成安卓平台所需so库，以提供导入安卓开发工程中，在安卓APP上利用ffmpeg库进行相关开发。

一、我的编译环境

1、系统：Ubuntu18.04.6

2、ffmpeg版本：ffmpeg-4.0.4

3、ndk版本：r17c（android-ndk-r17c-linux-x86_64）

二、下载交叉编译所需的ndk

因为我是在Ubuntu上编译的，所以需要下载的是Linux版本的ndk工具，具体下载地址如下：

https://dl.google.com/android/repository/android-ndk-r17c-linux-x86_64.zip

下载完之后，解压到某个文件夹下

三、下载ffmpeg源码

本文使用的是ffmpeg-4.0.4版本，下载并解压命令如下：

wget https://ffmpeg.org/releases/ffmpeg-4.0.4.tar.bz2
tar xvf ffmpeg-4.0.4.tar.bz2

解压之后得到ffmpeg-4.0.4文件夹。

四、编写编译脚本

在ffmpeg-4.0.4文件夹下创建编译脚本build.sh，ffmpeg编译可以有多个cpu平台编译，也可以单独编译某个cpu平台，同时ffmpeg的config配置也是可以自定义选择配置选项，这个可按需配置。以下是我的编译脚本，可供参考。

其中需要将NDK_HOME修改为自己本机的ndk存放路径，其次#choose which want to build下面可以选择想要编译哪个CPU架构的，一般主流是armeabi-v7a和arm64-v8a

#!/usr/bin/env bash

NDK_HOME=/home/weekend/android_ndk/android-ndk-r17c
PREFIX=android-build
HOST_PLATFORM=linux-x86_64
PLATFORM=android-18
PLATFORM_64=android-21

CONFIG_LOG_PATH=${PREFIX}/log
COMMON_OPTIONS=
CONFIGURATION=

build(){
    APP_ABI=$1
    echo "======== > Start build $APP_ABI"
    case ${APP_ABI} in
    armeabi )
        ARCH="arm"
        CPU="armv6"
        MARCH="armv6"
        TOOLCHAINS="$NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/$HOST_PLATFORM"
        CROSS_PREFIX="$TOOLCHAINS/bin/arm-linux-androideabi-"
        SYSROOT="$NDK_HOME/platforms/$PLATFORM/arch-arm"
        EXTRA_CFLAGS="-march=$MARCH"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -mfloat-abi=softfp -mfpu=vfp"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -I$NDK_HOME/sysroot/usr/include/arm-linux-androideabi"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -isysroot $NDK_HOME/sysroot"
        EXTRA_LDFLAGS="-lc -lm -ldl -llog"
        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-rpath-link=$SYSROOT/usr/lib -L$SYSROOT/usr/lib"
        EXTRA_OPTIONS="--disable-x86asm"
    ;;
    armeabi-v7a )
        ARCH="arm"
        CPU="armv7-a"
        MARCH="armv7-a"
        TOOLCHAINS="$NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/$HOST_PLATFORM"
        CROSS_PREFIX="$TOOLCHAINS/bin/arm-linux-androideabi-"
        SYSROOT="$NDK_HOME/platforms/$PLATFORM/arch-arm"
        EXTRA_CFLAGS="-march=$MARCH"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -mfloat-abi=softfp -mfpu=vfpv3-d16"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -I$NDK_HOME/sysroot/usr/include/arm-linux-androideabi"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -isysroot $NDK_HOME/sysroot"
        EXTRA_LDFLAGS="-lc -lm -ldl -llog"
        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--fix-cortex-a8"
        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-rpath-link=$SYSROOT/usr/lib -L$SYSROOT/usr/lib"
        EXTRA_OPTIONS="--enable-neon --disable-x86asm"
    ;;
    arm64-v8a )
        ARCH="aarch64"
        CPU="armv8-a"
        MARCH="armv8-a"
        TOOLCHAINS="$NDK_HOME/toolchains/aarch64-linux-android-4.9/prebuilt/$HOST_PLATFORM"
        CROSS_PREFIX="$TOOLCHAINS/bin/aarch64-linux-android-"
        SYSROOT="$NDK_HOME/platforms/$PLATFORM_64/arch-arm64"
        EXTRA_CFLAGS="-march=$MARCH"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -I$NDK_HOME/sysroot/usr/include/aarch64-linux-android"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -isysroot $NDK_HOME/sysroot"
        EXTRA_LDFLAGS="-lc -lm -ldl -llog"
        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-rpath-link=$SYSROOT/usr/lib -L$SYSROOT/usr/lib"
        EXTRA_OPTIONS="--enable-neon --disable-x86asm"
    ;;
    x86 )
        ARCH="x86"
        CPU="i686"
        MARCH="i686"
        TOOLCHAINS="$NDK_HOME/toolchains/x86-4.9/prebuilt/$HOST_PLATFORM"
        CROSS_PREFIX="$TOOLCHAINS/bin/i686-linux-android-"
        SYSROOT="$NDK_HOME/platforms/$PLATFORM/arch-x86"
        EXTRA_CFLAGS="-march=$MARCH"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -mtune=intel -mssse3 -mfpmath=sse -m32"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -I$NDK_HOME/sysroot/usr/include/i686-linux-android"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -isysroot $NDK_HOME/sysroot"
        EXTRA_LDFLAGS="-lc -lm -ldl -llog"
        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-rpath-link=$SYSROOT/usr/lib -L$SYSROOT/usr/lib"
        EXTRA_OPTIONS="--disable-asm"
    ;;
    x86_64 )
        ARCH="x86_64"
        CPU="x86_64"
        MARCH="x86-64"
        TOOLCHAINS="$NDK_HOME/toolchains/x86_64-4.9/prebuilt/$HOST_PLATFORM"
        CROSS_PREFIX="$TOOLCHAINS/bin/x86_64-linux-android-"
        SYSROOT="$NDK_HOME/platforms/$PLATFORM_64/arch-x86_64"
        EXTRA_CFLAGS="-march=$MARCH"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -mtune=intel -msse4.2 -mpopcnt -m64"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -I$NDK_HOME/sysroot/usr/include/x86_64-linux-android"
        EXTRA_CFLAGS="$EXTRA_CFLAGS -isysroot $NDK_HOME/sysroot"
        EXTRA_LDFLAGS="-lc -lm -ldl -llog"
        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-rpath-link=$SYSROOT/usr/lib64 -L$SYSROOT/usr/lib64"
        EXTRA_OPTIONS="--disable-asm"
    ;;
    esac

    echo "-------- > Start clean workspace"
    make clean

    echo "-------- > Start build configuration"
    CONFIGURATION="$COMMON_OPTIONS"
    CONFIGURATION="$CONFIGURATION --logfile=$CONFIG_LOG_PATH/config_$APP_ABI.log"
    CONFIGURATION="$CONFIGURATION --prefix=$PREFIX"
    CONFIGURATION="$CONFIGURATION --libdir=$PREFIX/libs/$APP_ABI"
    CONFIGURATION="$CONFIGURATION --incdir=$PREFIX/includes/$APP_ABI"
    CONFIGURATION="$CONFIGURATION --pkgconfigdir=$PREFIX/pkgconfig/$APP_ABI"
    CONFIGURATION="$CONFIGURATION --arch=$ARCH"
    CONFIGURATION="$CONFIGURATION --cpu=$CPU"
    CONFIGURATION="$CONFIGURATION --cross-prefix=$CROSS_PREFIX"
    CONFIGURATION="$CONFIGURATION --sysroot=$SYSROOT"
    CONFIGURATION="$CONFIGURATION --extra-ldexeflags=-pie"
    CONFIGURATION="$CONFIGURATION $EXTRA_OPTIONS"

    echo "-------- > Start config makefile with $CONFIGURATION --extra-cflags="${EXTRA_CFLAGS}" --extra-ldflags="${EXTRA_LDFLAGS}""
    ./configure ${CONFIGURATION} \
        --extra-cflags="$EXTRA_CFLAGS" \
        --extra-ldflags="$EXTRA_LDFLAGS"

    echo "-------- > Start make $APP_ABI with -j8"
    make j8

    echo "-------- > Start install $APP_ABI"
    make install
    echo "++++++++ > make and install $APP_ABI complete."

}

build_all(){

    COMMON_OPTIONS="$COMMON_OPTIONS --target-os=android"
    COMMON_OPTIONS="$COMMON_OPTIONS --disable-static"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-shared"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-protocols"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-cross-compile"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-optimizations"
    COMMON_OPTIONS="$COMMON_OPTIONS --disable-debug"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-small"
    COMMON_OPTIONS="$COMMON_OPTIONS --disable-doc"
    COMMON_OPTIONS="$COMMON_OPTIONS --disable-programs"
    COMMON_OPTIONS="$COMMON_OPTIONS --disable-ffmpeg"
    COMMON_OPTIONS="$COMMON_OPTIONS --disable-ffplay"
    COMMON_OPTIONS="$COMMON_OPTIONS --disable-ffprobe"
    COMMON_OPTIONS="$COMMON_OPTIONS --disable-symver"
    COMMON_OPTIONS="$COMMON_OPTIONS --disable-network"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-pthreads"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-mediacodec"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-jni"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-zlib"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-pic"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-avresample"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-decoder=h264"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-decoder=mpeg4"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-decoder=mjpeg"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-decoder=png"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-decoder=vorbis"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-decoder=opus"
    COMMON_OPTIONS="$COMMON_OPTIONS --enable-decoder=flac"

    echo "COMMON_OPTIONS=$COMMON_OPTIONS"
    echo "PREFIX=$PREFIX"
    echo "CONFIG_LOG_PATH=$CONFIG_LOG_PATH"

    mkdir -p ${CONFIG_LOG_PATH}

    #choose which want to build
#     build $app_abi
     build "armeabi"
     build "armeabi-v7a"
     build "arm64-v8a"
     build "x86"
     build "x86_64"
}

echo "-------- Start --------"

build_all

echo "-------- End --------"

编译完成后，在当前目录下生成一个android-build目录，

该目录的下的lib中就会有生成我们所需要的ffmpeg的so库，如下：

该so库即可导入Androidstudio中，以供安卓开发调用使用。可参考如下文章进行验证：

FFmpeg版Helloworld（Android平台）