【FFmpeg实战】ffmpeg播放器-音视频解码流程

音视频介绍

音视频解码流程

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FFmpeg解码的数据结构说明

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AVFormatContext：封装格式上下文结构体,全局结构体,保存了视频文件封装格式相关信息
AVInputFormat：每种封装格式，对应一个该结构体
AVStream[0]：视频文件中每个视频（音频）流对应一个该结构体
AVCodecContext：编码器上下文结构体，保存了视频（音频）编解码相关信息
AVCodec：每种视频（音频）编解码器(例如H.264解码器)对应一个该结构体

AVFormatContext数据结构说明

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iformat：输入视频的AVInputFormat
nb_streams：输入视频的AVStream 个数
streams：输入视频的AVStream []数组
duration：输入视频的时长（以微秒为单位）
bit_rate：输入视频的码率

AVInputFormat数据结构说明

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name：封装格式名称
long_name：封装格式的长名称
extensions：封装格式的扩展名
id：封装格式ID
一些封装格式处理的接口函数

AVStream数据结构说明

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id：序号
codec：该流对应的AVCodecContext
time_base：该流的时基
avg_frame_rate：该流的帧率

AVCodecContext数据结构说明

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codec：编解码器的AVCodec
width, height：图像的宽高
pix_fmt：像素格式
sample_rate：音频采样率
channels：声道数
sample_fmt：音频采样格式

AVCodec数据结构说明

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name：编解码器名称
long_name：编解码器长名称
type：编解码器类型
id：编解码器ID
一些编解码的接口函数

AVPacket数据结构说明

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pts：显示时间戳
dts：解码时间戳
data：压缩编码数据
size：压缩编码数据大小
stream_index：所属的AVStream

AVFrame数据结构说明

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data：解码后的图像像素数据（音频采样数据）
linesize：对视频来说是图像中一行像素的大小；对音频来说是整个音
width, height：图像的宽高
key_frame：是否为关键帧
pict_type：帧类型（只针对视频）。例如I，P，B

音视频实战

将编译好的FFmpeg库考入到工程

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编写CMakeLists.txt

cmake_minimum_required(VERSION 3.4.1)file(GLOB source_file *.cpp)message("source_file = ${source_file}")add_library(z-playerSHARED${source_file})include_directories(${CMAKE_SOURCE_DIR}/include)set(CMAKE_CXX_FLAGS  "${CMAKE_CXX_FLAGS} -L${CMAKE_SOURCE_DIR}/libs/${CMAKE_ANDROID_ARCH_ABI}")find_library(log-liblog)target_link_libraries(z-player# 方法一：使用-Wl 忽略顺序
#        -Wl,--start-group #忽略顺序引发的错误
#        avcodec avfilter avformat avutil swresample swscale
#        -Wl,--end-group# 方法二：调整顺序avformat avcodec avfilter avutil swresample swscale #必须要把avformat放在avcodec的前面${log-lib}z)

这里target_link_libraries方法有两个问题：

1.FFmpeg是需要依赖了libz.so库的如下图：
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所有要在target_link_libraries方法里添加z,否则会报错

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2.FFmpeg添加顺序问题，
当我们添加

avcodec avfilter avformat avutil swresample swscale

这样一个顺序时会报错
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解决方法有两个：

第一个：将avfilter放到avcodec前面就可以了

avformat avcodec avfilter avutil swresample swscale

第二个：使用-Wl忽略顺序

-Wl,--start-group #忽略顺序引发的错误
avcodec avfilter avformat avutil swresample swscale
-Wl,--end-group

编码

FFmpeg播放器结构类图

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编写ZPlayer.java类

public class ZPlayer implements LifecycleObserver, SurfaceHolder.Callback {private static final String TAG = ZPlayer.class.getSimpleName();static {System.loadLibrary("z-player");}private final long nativeHandle;private OnPrepareListener listener;private OnErrorListener onErrorListener;private SurfaceHolder mHolder;private OnProgressListener onProgressListener;public ZPlayer() {nativeHandle = nativeInit();}/*** 设置播放显示的画布* @param surfaceView*/public void setSurfaceView(SurfaceView surfaceView) {if (this.mHolder != null) {mHolder.removeCallback(this); // 清除上一次的}mHolder = surfaceView.getHolder();mHolder.addCallback(this);}/*** 让使用者设置播放的文件，或者直播地址* @param dataSource*/public void setDataSource(String dataSource){setDataSource(nativeHandle, dataSource);}/*** 准备好要播放的视频*/@OnLifecycleEvent(Lifecycle.Event.ON_RESUME)public void prepare() {Log.e(TAG,"ZPlayer->prepare");nativePrepare(nativeHandle);}/*** 开始播放*/public void start(){Log.e(TAG,"ZPlayer->start");nativeStart(nativeHandle);}/*** 停止播放*/@OnLifecycleEvent(Lifecycle.Event.ON_STOP)public void stop(){Log.e(TAG,"ZPlayer->stop");nativeStop(nativeHandle);}@OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)public void release(){Log.e(TAG,"ZPlayer->release");mHolder.removeCallback(this);nativeRelease(nativeHandle);}/*** JavaCallHelper 会反射调用此方法* @param errorCode*/public void onError(int errorCode, String ffmpegError){Log.e(TAG,"Java接收到回调了->onError:"+errorCode);String title = "\nFFmpeg给出的错误如下:\n";String msg = null;switch (errorCode){case Constant.FFMPEG_CAN_NOT_OPEN_URL:msg = "打不开视频"+title+ ffmpegError;break;case Constant.FFMPEG_CAN_NOT_FIND_STREAMS:msg = "找不到流媒体"+title+ ffmpegError;break;case Constant.FFMPEG_FIND_DECODER_FAIL:msg = "找不到解码器"+title+ ffmpegError;break;case Constant.FFMPEG_ALLOC_CODEC_CONTEXT_FAIL:msg = "无法根据解码器创建上下文"+title+ ffmpegError;break;case Constant.FFMPEG_CODEC_CONTEXT_PARAMETERS_FAIL:msg = "根据流信息 配置上下文参数失败"+title+ ffmpegError;break;case Constant.FFMPEG_OPEN_DECODER_FAIL:msg = "打开解码器失败"+title+ ffmpegError;break;case Constant.FFMPEG_NOMEDIA:msg = "没有音视频"+title+ ffmpegError;break;}if(onErrorListener != null ){onErrorListener.onError(msg);}}/*** JavaCallHelper 会反射调用此方法*/public void onPrepare(){Log.e(TAG,"Java接收到回调了->onPrepare");if(listener != null){listener.onPrepare();}}public void onProgress(int progress){if(onProgressListener != null){onProgressListener.onProgress(progress);}}@Overridepublic void surfaceCreated(SurfaceHolder surfaceHolder) {Log.e(TAG,"ZPlayer->surfaceCreated");}@Overridepublic void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {Log.e(TAG,"ZPlayer->surfaceChanged");nativeSetSurface(nativeHandle,surfaceHolder.getSurface());}@Overridepublic void surfaceDestroyed(SurfaceHolder surfaceHolder) {Log.e(TAG,"ZPlayer->surfaceDestroyed");}public int getDuration() {return getNativeDuration(nativeHandle);}public void seek(int playProgress) {nativeSeek(playProgress,nativeHandle);}public interface OnPrepareListener{void onPrepare();}public void setOnPrepareListener(OnPrepareListener listener){this.listener = listener;}public interface OnProgressListener{void onProgress(int progress);}public void setOnProgressListener(OnProgressListener listener){this.onProgressListener = listener;}public interface OnErrorListener{void onError(String errorCode);}public void setOnErrorListener(OnErrorListener listener){this.onErrorListener = listener;}private native long nativeInit();private native void setDataSource(long nativeHandle, String path);private  native void nativePrepare(long nativeHandle);private native void nativeStart(long nativeHandle);private native void nativeStop(long nativeHandle);private  native void nativeRelease(long nativeHandle);private native void nativeSetSurface(long nativeHandle, Surface surface);private native int getNativeDuration(long nativeHandle);private native void nativeSeek(int playValue,long nativeHandle);
}

编写MainActivity.java类

public class MainActivity extends AppCompatActivity implements SeekBar.OnSeekBarChangeListener {private ActivityMainBinding binding;private int PERMISSION_REQUEST = 0x1001;private ZPlayer mPlayer;// 用户是否拖拽里private boolean isTouch = false;// 获取native层的总时长private int duration ;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);binding = ActivityMainBinding.inflate(getLayoutInflater());setContentView(binding.getRoot());checkPermission();binding.seekBar.setOnSeekBarChangeListener(this);mPlayer = new ZPlayer();getLifecycle().addObserver(mPlayer);mPlayer.setSurfaceView(binding.surfaceView);mPlayer.setDataSource("/sdcard/demo.mp4");
//        mPlayer.setDataSource("/sdcard/chengdu.mp4");mPlayer.setOnPrepareListener(new ZPlayer.OnPrepareListener() {@Overridepublic void onPrepare() {duration = mPlayer.getDuration();runOnUiThread(new Runnable() {@Overridepublic void run() {binding.seekBarTimeLayout.setVisibility(duration != 0 ? View.VISIBLE : View.GONE);if(duration != 0){binding.tvTime.setText("00:00/"+getMinutes(duration)+":"+getSeconds(duration));}binding.tvState.setTextColor(Color.GREEN);binding.tvState.setText("恭喜init初始化成功");}});mPlayer.start();}});mPlayer.setOnErrorListener(new ZPlayer.OnErrorListener() {@Overridepublic void onError(String errorCode) {runOnUiThread(new Runnable() {@Overridepublic void run() {binding.tvState.setTextColor(Color.RED);binding.tvState.setText(errorCode);}});}});mPlayer.setOnProgressListener(new ZPlayer.OnProgressListener() {@Overridepublic void onProgress(int progress) {if (!isTouch){runOnUiThread(new Runnable() {@Overridepublic void run() {// 非直播，是本地视频文件if(duration != 0) {binding.tvTime.setText(getMinutes(progress) + ":" + getSeconds(progress)+ "/" + getMinutes(duration) + ":" + getSeconds(duration));binding.seekBar.setProgress(progress * 100 / duration);}}});}}});}private void checkPermission() {if(ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) !=PackageManager.PERMISSION_GRANTED){Log.e("zuo","无权限，去申请权限");ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, PERMISSION_REQUEST);}else {Log.e("zuo","有权限");}}@Overridepublic void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {super.onRequestPermissionsResult(requestCode, permissions, grantResults);if(requestCode == PERMISSION_REQUEST){Log.e("zuo","申请到权限"+grantResults.length);if (grantResults[0] == PackageManager.PERMISSION_GRANTED){Toast.makeText(this,"已申请权限",Toast.LENGTH_SHORT).show();}else {Toast.makeText(this,"申请权限失败",Toast.LENGTH_SHORT).show();}}}private String getSeconds(int duration){int seconds = duration % 60;String str ;if(seconds <= 9){str = "0"+seconds;}else {str = "" + seconds;}return str;}private String getMinutes(int duration){int minutes = duration / 60;String str ;if(minutes <= 9){str = "0"+minutes;}else {str = "" + minutes;}return str;}/*** 当前拖动条进度发送了改变，毁掉此方法* @param seekBar 控件* @param progress 1～100* @param fromUser 是否用户拖拽导致到改变*/@Overridepublic void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {if(fromUser) {binding.tvTime.setText(getMinutes(progress * duration / 100) + ":" + getSeconds(progress * duration / 100)+ "/" + getMinutes(duration) + ":" + getSeconds(duration));}}//手按下去，毁掉此方法@Overridepublic void onStartTrackingTouch(SeekBar seekBar) {isTouch = true;}// 手松开(SeekBar当前值)回调此方法@Overridepublic void onStopTrackingTouch(SeekBar seekBar) {isTouch = false;int seekBarProgress = seekBar.getProgress();int playProgress = seekBarProgress * duration / 100;mPlayer.seek(playProgress);}
}

编写native-lib.cpp

java调用native方法的入口

#include <jni.h>
#include <string>
#include "ZPlayer.h"
#define LOG_TAG "native-lib"ZPlayer *zPlayer = nullptr;
JavaVM *javaVm = nullptr;
JavaCallHelper *helper = nullptr;
ANativeWindow *window = nullptr;
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;int JNI_OnLoad(JavaVM *vm,void *r){javaVm = vm;return JNI_VERSION_1_6;
}extern "C"
JNIEXPORT jlong JNICALL
Java_com_zxj_zplayer_ZPlayer_nativeInit(JNIEnv *env, jobject thiz) {//创建播放器helper = new JavaCallHelper(javaVm,env,thiz);zPlayer = new ZPlayer(helper);return (jlong)zPlayer;
}extern "C"
JNIEXPORT void JNICALL
Java_com_zxj_zplayer_ZPlayer_setDataSource(JNIEnv *env, jobject thiz, jlong native_handle,jstring path) {const char *dataSource = env->GetStringUTFChars(path, nullptr);ZPlayer *zPlayer = reinterpret_cast<ZPlayer *>(native_handle);zPlayer->setDataSource(dataSource);env->ReleaseStringUTFChars(path,dataSource);
}extern "C"
JNIEXPORT void JNICALL
Java_com_zxj_zplayer_ZPlayer_nativePrepare(JNIEnv *env, jobject thiz, jlong native_handle) {ZPlayer *zPlayer = reinterpret_cast<ZPlayer *>(native_handle);zPlayer->prepare();
}extern "C"
JNIEXPORT void JNICALL
Java_com_zxj_zplayer_ZPlayer_nativeStart(JNIEnv *env, jobject thiz, jlong native_handle) {ZPlayer *zPlayer = reinterpret_cast<ZPlayer *>(native_handle);zPlayer->start();
}extern "C"
JNIEXPORT void JNICALL
Java_com_zxj_zplayer_ZPlayer_nativeStop(JNIEnv *env, jobject thiz, jlong native_handle) {ZPlayer *zPlayer = reinterpret_cast<ZPlayer *>(native_handle);zPlayer->stop();if(helper){DELETE(helper);}
}extern "C"
JNIEXPORT void JNICALL
Java_com_zxj_zplayer_ZPlayer_nativeRelease(JNIEnv *env, jobject thiz, jlong native_handle) {pthread_mutex_lock(&mutex);if(window){ANativeWindow_release(window);window = nullptr;}pthread_mutex_unlock(&mutex);DELETE(helper);DELETE(zPlayer);DELETE(javaVm);DELETE(window);
}extern "C"
JNIEXPORT void JNICALL
Java_com_zxj_zplayer_ZPlayer_nativeSetSurface(JNIEnv *env, jobject thiz, jlong native_handle,jobject surface) {pthread_mutex_lock(&mutex);//先释放之前的显示窗口if(window){LOGE("nativeSetSurface->window=%p",window);ANativeWindow_release(window);window = nullptr;}window = ANativeWindow_fromSurface(env,surface);ZPlayer *zPlayer = reinterpret_cast<ZPlayer *>(native_handle);zPlayer->setWindow(window);pthread_mutex_unlock(&mutex);
}extern "C"
JNIEXPORT jint JNICALL
Java_com_zxj_zplayer_ZPlayer_getNativeDuration(JNIEnv *env, jobject thiz, jlong native_handle) {ZPlayer *zPlayer = reinterpret_cast<ZPlayer *>(native_handle);if(zPlayer){return zPlayer->getDuration();}return 0;
}extern "C"
JNIEXPORT void JNICALL
Java_com_zxj_zplayer_ZPlayer_nativeSeek(JNIEnv *env, jobject thiz, jint play_value,jlong native_handle) {ZPlayer *zPlayer = reinterpret_cast<ZPlayer *>(native_handle);if(zPlayer){zPlayer->seek(play_value);}
}

编写JavaCallHelper.cpp

这个类主要用作:处理音视频后各个状态回调java方法

#include "JavaCallHelper.h"
#define LOG_TAG "JavaCallHelper"JavaCallHelper::JavaCallHelper(JavaVM *vm, JNIEnv *env, jobject instace) {this->vm = vm;//如果在主线程回调this->env = env;//一旦涉及到jobject 跨方法/跨线程 就需要创建全局引用this->instace = env->NewGlobalRef(instace);jclass clazz = env->GetObjectClass(instace);onErrorId = env->GetMethodID(clazz, "onError", "(ILjava/lang/String;)V");onPrepareId = env->GetMethodID(clazz, "onPrepare", "()V");onProgressId = env->GetMethodID(clazz, "onProgress", "(I)V");
}JavaCallHelper::~JavaCallHelper() {env->DeleteGlobalRef(this->instace);
}void JavaCallHelper::onError(int thread, int errorCode,char * ffmpegError) {//主线程if(thread == THREAD_MAIN){jstring _ffmpegError = env->NewStringUTF(ffmpegError);env->CallVoidMethod(instace,onErrorId,errorCode,_ffmpegError);} else{//子线程JNIEnv *env;if (vm->AttachCurrentThread(&env, 0) != JNI_OK) {return;}jstring _ffmpegError = env->NewStringUTF(ffmpegError);env->CallVoidMethod(instace,onErrorId,errorCode,_ffmpegError);vm->DetachCurrentThread();//解除附加，必须要}
}void JavaCallHelper::onPrepare(int thread) {//主线程if(thread == THREAD_MAIN){env->CallVoidMethod(instace,onPrepareId);} else{//子线程JNIEnv *env;if (vm->AttachCurrentThread(&env, 0) != JNI_OK) {return;}env->CallVoidMethod(instace,onPrepareId);vm->DetachCurrentThread();}
}void JavaCallHelper::onProgress(int thread, int progress) {if(thread == THREAD_MAIN){env->CallVoidMethod(instace,onProgressId,progress);} else{//子线程JNIEnv *env;if (vm->AttachCurrentThread(&env, 0) != JNI_OK) {return;}env->CallVoidMethod(instace,onProgressId,progress);vm->DetachCurrentThread();}
}

编写ZPlayer.cpp

主要处理音视频的

#include <cstring>
#include "ZPlayer.h"
#include "macro.h"void *task_prepare(void *args) {ZPlayer *zFmpeg = static_cast<ZPlayer *>(args);zFmpeg->_prepare();return 0;
}ZPlayer::ZPlayer(JavaCallHelper *callHelper, const char *dataSource) {this->callHelper = callHelper;//这样写会报错，dataSource会在native-lib.cpp里的方法里会被释放掉，那么这里拿到的dataSource是悬空指针
//    this->dataSource = const_cast<char *>(dataSource);this->dataSource = new char[strlen(dataSource)];strcpy(this->dataSource, dataSource);
}ZPlayer::~ZPlayer() {//释放
//    delete this->dataSource;
//    this->dataSource = nullptr;DELETE(dataSource);DELETE(callHelper);
}void ZPlayer::prepare() {pthread_create(&pid, 0, task_prepare, this);
}void ZPlayer::_prepare() {//初始化网络，不调用这个，FFmpage是无法联网的avformat_network_init();//AVFormatContext 包含了视频的信息(宽、高等)formatContext = 0;//1、打开媒体地址(文件地址、直播地址)int ret = avformat_open_input(&formatContext, dataSource, 0, 0);//ret不为0表示打开媒体失败if (ret) {LOGE("打开媒体失败:%s", av_err2str(ret));callHelper->onError(THREAD_CHILD, FFMPEG_CAN_NOT_OPEN_URL);return;}//2、查找媒体中的音视频流ret = avformat_find_stream_info(formatContext, 0);//小于0则失败if (ret < 0) {LOGE("查找流失败:%s", av_err2str(ret));callHelper->onError(THREAD_CHILD, FFMPEG_CAN_NOT_FIND_STREAMS);return;}//经过avformat_find_stream_info方法后，formatContext->nb_streams就有值了unsigned int streams = formatContext->nb_streams;//nb_streams :几个流(几段视频/音频)for (int i = 0; i < streams; ++i) {//可能代表是一个视频，也可能代表是一个音频AVStream *stream = formatContext->streams[i];//包含了解码 这段流的各种参数信息(宽、高、码率、帧率)AVCodecParameters *codecpar = stream->codecpar;//无论视频还是音频都需要干的一些事情（获得解码器）// 1、通过当前流使用的编码方式，查找解码器AVCodec *avCodec = avcodec_find_decoder(codecpar->codec_id);if (avCodec == nullptr) {LOGE("查找解码器失败:%s", av_err2str(ret));callHelper->onError(THREAD_CHILD, FFMPEG_FIND_DECODER_FAIL);return;}//2、获得解码器上下文AVCodecContext *context3 = avcodec_alloc_context3(avCodec);if (context3 == nullptr) {LOGE("创建解码上下文失败:%s", av_err2str(ret));callHelper->onError(THREAD_CHILD, FFMPEG_ALLOC_CODEC_CONTEXT_FAIL);return;}//3、设置上下文内的一些参数 (context->width)ret = avcodec_parameters_to_context(context3, codecpar);if (ret < 0) {LOGE("设置解码上下文参数失败:%s", av_err2str(ret));callHelper->onError(THREAD_CHILD, FFMPEG_CODEC_CONTEXT_PARAMETERS_FAIL);return;}// 4、打开解码器ret = avcodec_open2(context3, avCodec, 0);if (ret != 0) {LOGE("打开解码器失败:%s", av_err2str(ret));callHelper->onError(THREAD_CHILD, FFMPEG_OPEN_DECODER_FAIL);return;}//音频if (codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {audioChannel = new AudioChannel;} else if (codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {videoChannel = new VideoChannel;}}if (!audioChannel && !videoChannel) {LOGE("没有音视频");callHelper->onError(THREAD_CHILD, FFMPEG_NOMEDIA);return;}// 准备完了 通知java 你随时可以开始播放callHelper->onPrepare(THREAD_CHILD);
}

核心代码差不多是这些，现在我们可以先测试一下，编译运行会发现报错

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报这个错是因为，FFmpeg的版本问题，在上一篇《FFmpeg编译》中我们在编译FFmpeg的库的时候，指定了-D__ANDROID_API__=21，而我们项目中的minSdkVersion为14，所以需要修改minSdkVersion为21就可以了。

最后运行测试是没有问题的。

其他手机奔溃解决方法

上面编译源码使用到是"armeabi-v7a",但是有的手机是"arm64-v8a"架构到，所以直接运行就会报错，找不到so库

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1.这时有两种解决方法

在build.gradle文件里加入ndk{abiFilters "armeabi-v7a"}就可以了
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2.重新编译一个"arm64-v8a"的静态库，修改build.sh文件

#!/bin/bash#执行生成makefile的shell脚本
PREFIX=./android/armeabi-v7a2NDK_ROOT=/home/zuojie/android-ndk-r17cCPU=aarch64-linux-android
TOOLCHAIN=$NDK_ROOT/toolchains/$CPU-4.9/prebuilt/linux-x86_64FLAGS="-isystem $NDK_ROOT/sysroot/usr/include/$CPU -D__ANDROID_API__=21 -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -Wa,--noexecstack -Wformat -Werror=format-security  -O0 -fPIC"
#FLAGS="-isystem $NDK_ROOT/sysroot/usr/include/$CPU -D__ANDROID_API__=21 -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -march=armv7-a -mfloat-abi=softfp -mfpu=vfpv3-d16 -mthumb -Wa,--noexecstack -Wformat -Werror=format-security  -O0 -fPIC"INCLUDES=" -isystem $NDK_ROOT/sources/android/support/include"# \ 换行连接符
./configure --prefix=$PREFIX \--enable-small \--disable-programs \--disable-avdevice \--disable-postproc \--disable-encoders \--disable-muxers \--disable-filters \--enable-cross-compile \--cross-prefix=$TOOLCHAIN/bin/$CPU- \--disable-shared \--enable-static \--sysroot=$NDK_ROOT/platforms/android-21/arch-arm64 \--extra-cflags="$FLAGS $INCLUDES" \--extra-cflags="-isysroot $NDK_ROOT/sysroot/" \--arch=arm64 \--target-os=android # 清理一下 
make clean
#执行makefile
make install