编译FFmpeg4.1.3并移植到Android app中使用（最详细的FFmpeg-Android编译教程）

• 如果需要支持硬件解码，推荐看这篇文章 FFmpeg一键编译Android armv7-a arm64

1.搭建编译环境

1.安装ubuntu14.04，安装完成后执行以下命令

apt-get update
apt-get install yasm
apt-get install pkg-config

2.下载ndk

这里用最新稳定版ndk r19c：下载ndk-r19c
将ndk下载到 /home/ndk/目录下，下载完成后执行unzip android-ndk-r19c-linux-x86_64.zip解压

3.下载FFmpeg4.1.3

下载FFmpeg-n4.1.3
下载完成后执行tar -zxvf n4.1.3.tar.gz解压

2.编译FFmpeg

1.修改configure

进入源码根目录，用vim打开configure，找到

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)'  

将其修改为

SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(FULLNAME)-$(LIBMAJOR)$(SLIBSUF)'  
LIB_INSTALL_EXTRA_CMD='$$(RANLIB)"$(LIBDIR)/$(LIBNAME)"'  
SLIB_INSTALL_NAME='$(SLIBNAME_WITH_MAJOR)'  
SLIB_INSTALL_LINKS='$(SLIBNAME)'  

2.配置编译脚本

在源码根目录新建build.sh，内容如下：

#!/bin/bash
NDK=/home/ndk/android-ndk-r19c
ADDI_LDFLAGS="-fPIE -pie"
ADDI_CFLAGS="-fPIE -pie -march=armv7-a -mfloat-abi=softfp -mfpu=neon"
CPU=armv7-a
ARCH=arm
HOST=arm-linux
SYSROOT=$NDK/toolchains/llvm/prebuilt/linux-x86_64/sysroot
TOOLCHAIN=$NDK/toolchains/llvm/prebuilt/linux-x86_64/bin
PREFIX=$(pwd)/android/$CPU
x264=$(pwd)/x264/android/$CPU
export PATH=$x264/bin:$PATH
export PATH=$x264/include:$PATH
export PATH=$x264/lib:$PATH
export PKG_CONFIG_PATH=$x264/lib/pkgconfig:$PKG_CONFIG_PATH
configure()
{
    ./configure \
    --prefix=$PREFIX \
	--toolchain=clang-usan \
    --enable-cross-compile \
    --target-os=android \
    --arch=$ARCH \
    --sysroot=$SYSROOT \
	--cc=$TOOLCHAIN/armv7a-linux-androideabi21-clang \
	--cxx=$TOOLCHAIN/armv7a-linux-androideabi21-clang++ \
    --strip=$TOOLCHAIN/arm-linux-androideabi-strip \
    --extra-cflags="$ADDI_CFLAGS" \
    --extra-ldflags="$ADDI_LDFLAGS" \
    --disable-encoders \
    --disable-decoders \
    --disable-avdevice \
    --disable-static \
    --disable-doc \
    --disable-ffplay \
    --disable-network \
    --disable-doc \
    --disable-symver \
	--disable-ffprobe \
	--enable-neon \
    --enable-shared \
    --enable-libx264 \
    --enable-gpl \
    --enable-pic \
    --enable-jni \
    --enable-pthreads \
    --enable-mediacodec \
    --enable-encoder=aac \
    --enable-encoder=gif \
    --enable-encoder=libopenjpeg \
    --enable-encoder=libmp3lame \
    --enable-encoder=libwavpack \
    --enable-encoder=libx264 \
    --enable-encoder=mpeg4 \
    --enable-encoder=pcm_s16le \
    --enable-encoder=png \
    --enable-encoder=mjpeg \
    --enable-encoder=srt \
    --enable-encoder=subrip \
    --enable-encoder=yuv4 \
    --enable-encoder=text \
    --enable-decoder=aac \
    --enable-decoder=aac_latm \
    --enable-decoder=libopenjpeg \
    --enable-decoder=mp3 \
    --enable-decoder=mpeg4_mediacodec \
    --enable-decoder=pcm_s16le \
    --enable-decoder=flac \
    --enable-decoder=flv \
    --enable-decoder=gif \
    --enable-decoder=png \
    --enable-decoder=srt \
    --enable-decoder=xsub \
    --enable-decoder=yuv4 \
    --enable-decoder=vp8_mediacodec \
    --enable-decoder=h264_mediacodec \
    --enable-decoder=hevc_mediacodec \
    --enable-bsf=aac_adtstoasc \
    --enable-bsf=h264_mp4toannexb \
    --enable-bsf=hevc_mp4toannexb \
    --enable-bsf=mpeg4_unpack_bframes

}

build()
{
    configure
    make clean
    make -j4
    make install
}

build

*注意 x264需要自己编译引入，ffmpeg并不包含x264

可以根据自己的需求对模块进行裁剪，
查看所有编译配置选项：./configure --help
查看支持的解码器：./configure --list-decoders
查看支持的编码器：./configure --list-encoders
查看支持的硬件加速：./configure --list-hwaccels

赋予脚本执行权限：chmod +x build.sh
执行脚本开始编译：./build.sh
如果一切顺利就可以在源码更目录下的android/armv7-a/lib/下找到我们需要的.so文件了

3.移植到Android App中

1.JNI编译

（1）将编译后的FFmpeg源码目录打包并复制到Windows中，在任意目录下新建jni文件夹，将 android\armv7-a\lib 目录下的.so文件复制到 jni\prebuilt\ 目录下；
将 android\armv7-a\include 目录下的所有文件夹复制到 jni 目录下；
将 源码根目录下的config.h复制到 jni 目录下；
将 fftools\ 目录下的以下文件复制到 jni 目录下：
cmdutils.h
ffmpeg.h
ffmpeg.c
ffmpeg_opt.c
ffmpeg_filter.c
cmdutils.c
ffmpeg_hw.c

（2）修改cmdutils
打开cmdutils.h，将
void show_help_children(const AVClass *class, int flags);
改为
void show_help_children(const AVClass *clazz, int flags);
否则和C++一起编译会出问题

（3）修改ffmpeg.c
找到入口函数int main(int argc, char **argv)
将其修改为int ffmpeg_exec(int argc, char **argv)
将此函数中所有调用exit_program()的地方都注释掉，并在函数末尾添加以下代码重置状态：

nb_filtergraphs = 0;
nb_output_files = 0;
nb_output_streams = 0;
nb_input_files = 0;
nb_input_streams = 0;

同时在ffmpeg.h中添加函数申明：
int ffmpeg_exec(int argc, char **argv);

（4）输出ADB日志
在ffmpeg.c中引入头文件

#include "android/log.h"

#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG  , "ffmpeg.c", __VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR  , "ffmpeg.c", __VA_ARGS__)

实现log_callback_null函数

static void log_callback_null(void *ptr, int level, const char *fmt, va_list vl)
{
    static int print_prefix = 1;
    static int count;
    static char prev[1024];
    char line[1024];
    static int is_atty;

    av_log_format_line(ptr, level, fmt, vl, line, sizeof(line), &print_prefix);

    strcpy(prev, line);

    if (level <= AV_LOG_WARNING) {
        LOGE("%s", line);
    } else {
        LOGD("%s", line);
    }
}

（5）实现JNI接口
编写ffmpeg-invoke.cpp并放到 jni 目录下：

#include 
#include 
#include "android/log.h"

#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, "ffmpeg-invoke", __VA_ARGS__)

extern "C"{
#include "ffmpeg.h"
#include "libavcodec/jni.h"
}

extern "C"
JNIEXPORT jint JNICALL
Java_com_github_ffmpegtest_jni_FFmpegCmd_run(JNIEnv *env, jclass type, jint cmdLen,
                                             jobjectArray cmd) {
    //set java vm
    JavaVM *jvm = NULL;
    env->GetJavaVM(&jvm);
    av_jni_set_java_vm(jvm, NULL);

    char *argCmd[cmdLen] ;
    jstring buf[cmdLen];

    for (int i = 0; i < cmdLen; ++i) {
        buf[i] = static_cast(env->GetObjectArrayElement(cmd, i));
        char *string = const_cast(env->GetStringUTFChars(buf[i], JNI_FALSE));
        argCmd[i] = string;
        LOGD("argCmd=%s",argCmd[i]);
    }

    int retCode = ffmpeg_exec(cmdLen, argCmd);
    LOGD("ffmpeg-invoke: retCode=%d",retCode);

    return retCode;

}

注意：将com_github_ffmpegtest_jni_FFmpegCmd改为自己工程中的JAVA文件对应的包名
（6）编写.mk文件
编写Android.mk文件并放到 jni 目录

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE :=  libavutil
LOCAL_SRC_FILES := prebuilt/libavutil.so
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE :=  libswresample
LOCAL_SRC_FILES := prebuilt/libswresample.so
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE :=  libswscale
LOCAL_SRC_FILES := prebuilt/libswscale.so
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavcodec
LOCAL_SRC_FILES := prebuilt/libavcodec.so
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavformat
LOCAL_SRC_FILES := prebuilt/libavformat.so
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavfilter
LOCAL_SRC_FILES := prebuilt/libavfilter.so
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libpostproc
LOCAL_SRC_FILES := prebuilt/libpostproc.so
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := ffmpeg-invoke

LOCAL_SRC_FILES :=ffmpeg-invoke.cpp \
                 cmdutils.c \
                 ffmpeg_filter.c \
                 ffmpeg_opt.c \
                 ffmpeg_hw.c \
                 ffmpeg.c


LOCAL_C_INCLUDES := D:\libs\FFmpeg-n4.1.3

LOCAL_LDLIBS := -llog -ljnigraphics -lz -landroid -lm -pthread -L$(SYSROOT)/usr/lib
LOCAL_SHARED_LIBRARIES := libavcodec libavfilter libavformat libavutil libswresample libswscale libpostproc

include $(BUILD_SHARED_LIBRARY)

注意：将LOCAL_C_INCLUDES改为自己电脑中FFmpeg源码所在目录

编写Application.mk并放到 …\jni\目录下

APP_ABI := armeabi-v7a
APP_PLATFORM=android-21
APP_OPTIM := release
APP_STL := stlport_static

（7）编译
确认所需文件都准备就绪：

打开CMD，进入该目录，执行ndk-build开始编译(确保ndk路径已经配置到环境变量中)
编译过程中可能出现的报错：
1.error: invalid suffix on literal; C++11 requires a space between literal and identifier [-Wreserved-user-defined-literal] snprintf(name, sizeof(name), "0x%"PRIx64, ch_layout);
解决方法：在cmdutils.h中找到 "0x%"PRIx64，在PRIx64前面加个空格即可。

2.error: assigning to 'BenchmarkTimeStamps' (aka 'struct BenchmarkTimeStamps') from incompatible type 'int64_t' (aka 'long long') current_time = ti = getutime();
解决方法：在ffmpeg.c中找到current_time = ti = getutime();，将这行代码改为current_time.sys_usec = ti = getutime();

3.error: undefined reference to 'postproc_version'
解决方法：在cmdutils.c中注释这行代码
PRINT_LIB_INFO(postproc, POSTPROC, flags, level);

4.error: undefined reference to 'getutime'
解决方法：在ffmpeg.c中添加下面这个函数：

static int64_t getutime(void)
{
#if HAVE_GETRUSAGE
    struct rusage rusage;

    getrusage(RUSAGE_SELF, &rusage);
    return (rusage.ru_utime.tv_sec * 1000000LL) + rusage.ru_utime.tv_usec;
#elif HAVE_GETPROCESSTIMES
    HANDLE proc;
    FILETIME c, e, k, u;
    proc = GetCurrentProcess();
    GetProcessTimes(proc, &c, &e, &k, &u);
    return ((int64_t) u.dwHighDateTime << 32 | u.dwLowDateTime) / 10;
#else
    return av_gettime_relative();
#endif
}

编译成功可以看到生成的.so文件：

在jni同级目录下找到libs目录，libs\armeabi-v7a目录下的.so文件就是我们最终需要的动态链接库：

2.新建Android Studio测试工程 FFmpegTest

（1）在FFmpegTest\app\src\main\目录下新建jniLibs目录，将上一步编译生成的 \libs\armeabi-v7a文件夹复制到jniLibs目录下;
在com.github.ffmpegtest.jni路径下新建FFmpegCmd.java

public class FFmpegCmd {
    static {
        System.loadLibrary("avutil");
        System.loadLibrary("avcodec");
        System.loadLibrary("swresample");
        System.loadLibrary("avformat");
        System.loadLibrary("swscale");
        System.loadLibrary("avfilter");
        System.loadLibrary("ffmpeg-invoke");
    }

    private static native int run(int cmdLen, String[] cmd);
    public static native String test();

    public static int run(String[] cmd){
        return run(cmd.length,cmd);
    }
}

（2）测试FFmpeg命令

public class MainActivity extends AppCompatActivity {

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

        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE)
                != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
                    100);
        }

        TextView tvMessage = findViewById(R.id.tv_message);
        tvMessage.setText(FFmpegInvoke.test());

        ffmpegTest();
    }

    private void ffmpegTest() {
        new Thread(){
            @Override
            public void run() {
                long startTime = System.currentTimeMillis();
                String input = "/sdcard/Movies/Replay_2018.05.08-13.46.mp4";
                String output = "/sdcard/Movies/output.mp4";
                //剪切视频从00：20-00：28的片段
                String cmd = "ffmpeg -d -ss 00:00:20 -t 00:00:08 -i %s -vcodec copy -acodec copy %s";
                cmd = String.format(cmd,input,output);
                FFmpegCmd.run(cmd.split(" "));
                Log.d("FFmpegTest", "run: 耗时："+(System.currentTimeMillis()-startTime));
            }
        }.start();


    }
}

执行完毕后再/sdcard/Movies/目录下找到output.mp4，打开播放确实是我们想要的结果，说明FFmpeg的命令成功执行了。