[1].FFMpeg入门之 - Android集成FFMpeg

我的开发环境是ubuntu17.04 + as2.3.3 + android-ndk-r11c. 不同的环境配置不一样，请根据实际环境做一定的调整。
1.首先去github上下载ffmpeg的源码：https://github.com/FFmpeg/FFmpeg
2.打开源码工程,找到configure文件，vim打开他。找到这几行

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)'

目的是将生成.so名称规范化，用以满足android build。

image.png

3.在源码目录下新建一个build_android.sh文件。
内容：

#!/bin/bash
NDK=/home/dengxuan/Android/Sdk/ndk-bundle
SYSROOT=$NDK/platforms/android-9/arch-arm/
TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64
export TMPDIR=/home/dengxuan/workspace/github/FFmpeg/jni/temp
function build_one
{
./configure \
 --prefix=$PREFIX \   //--prefix安装路径，如果发现设置了不生效，它还是给你安装到/usr/local目录下去了。可以修改.configure文件，找到prefix_default 将其改成你要的目录即可
 --enable-shared \
 --disable-static \
 --disable-doc \
 --disable-ffmpeg \
 --disable-ffplay \
 --disable-ffprobe \
 --disable-ffserver \
 --disable-avdevice \
 --disable-doc \
 --disable-symver \
 --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
 --target-os=linux \
 --arch=arm \
 --enable-cross-compile \
 --sysroot=$SYSROOT \
 --extra-cflags="-Os -fpic $ADDI_CFLAGS" \
 --extra-ldflags="$ADDI_LDFLAGS" \
 $ADDITIONAL_CONFIGURE_FLAG
make clean
make
make install
}
CPU=armeabi-v7a
PREFIX=$(pwd)/android/$CPU
ADDI_CFLAGS="-marm"
build_one

解释下：
[1].NDK 填你本地的ndk安装路径。执行命令 which ndk-build 即可看到目录在哪。
[2].TOOLCHAIN 找到你自己ndk目录下的toolchains，然后后面的路径都要改成自己的，如果是再windows上，可能toolchains就是TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/windows。需要依据实际环境调整。
[3].export TMPDIR=/home/dengxuan/workspace/github/FFmpeg/jni/temp。这一行是因为刚开始build的时候没加这一行，有可能会报arm-linux-androideabi-gcc-4.4.3 is unable to create an executable file 这个错。基本上就是执行这个sh文件的时候，创建目录的时候没有权限。需要手动先把文件夹创建好。因为执行命令的过程中会一直有零时文件生成，这里相当于是建了个文件夹，让他在这个文件夹下生成零时文件。
[4].CPU 处理器类型 armeabi-v7a

4.打开命令行执行 ./build_android.sh 命令就开始构建了。

image.png

image.png

5.构建成功后，会在当前目录下生成一个android文件夹，也就是上面的脚本中指定的PREFIX=$(pwd)/android/$CPU

image.png

6.将FFMpeg集成进现有的工程。我这里是集成到一个lib工程下，集成到主工程也可参照下面的方法
首先在lib工程下新建libs文件夹，讲第五步生成的文件拷贝进来，目录树结构如下：

image.png

然后修改lib工程的build.gradle文件：
添加如下配置：

image.png

externalNativeBuild {
            cmake {
                cppFlags "-frtti -fexceptions"
            }
        }
        ndk {
            abiFilters 'armeabi-v7a'
        }
externalNativeBuild {
        cmake {
            path "CMakeLists.txt"
        }
    }
sourceSets {
        main {
            jniLibs.srcDirs = ['libs']
        }
    }

再然后在lib工程下新建上面写的CMakeLists.txt文件

# Sets the minimum version of CMake required to build the native
# library. You should either keep the default value or only pass a
# value of 3.4.0 or lower.

cmake_minimum_required(VERSION 3.4.1)

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 )

set(distribution_DIR ${CMAKE_SOURCE_DIR}/../../../../libs)

add_library( avutil-55
             SHARED
             IMPORTED )
set_target_properties( avutil-55
                       PROPERTIES IMPORTED_LOCATION
                       ../../../../libs/armeabi-v7a/libavutil-55.so )

add_library( swresample-2
             SHARED
             IMPORTED )
set_target_properties( swresample-2
                       PROPERTIES IMPORTED_LOCATION
                       ../../../../libs/armeabi-v7a/libswresample-2.so )
add_library( avcodec-57
             SHARED
             IMPORTED )
set_target_properties( avcodec-57
                       PROPERTIES IMPORTED_LOCATION
                       ../../../../libs/armeabi-v7a/libavcodec-57.so )
add_library( avfilter-6
             SHARED
             IMPORTED)
set_target_properties( avfilter-6
                       PROPERTIES IMPORTED_LOCATION
                       ../../../../libs/armeabi-v7a/libavfilter-6.so )
add_library( swscale-4
             SHARED
             IMPORTED)
set_target_properties( swscale-4
                       PROPERTIES IMPORTED_LOCATION
                       ../../../../libs/armeabi-v7a/libswscale-4.so )

add_library( avformat-57
             SHARED
             IMPORTED)
set_target_properties( avformat-57
                       PROPERTIES IMPORTED_LOCATION
                       ../../../../libs/armeabi-v7a/libavformat-57.so )



set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++11")

add_library( native-lib
             SHARED
             src/main/cpp/native-lib.cpp
              )

include_directories(libs/include)

#target_include_directories(native-lib PRIVATE libs/include)

target_link_libraries( native-lib swresample-2 avcodec-57 avfilter-6 swscale-4 avformat-57
                       ${log-lib} )

再在main目录下新建cpp目录，添加如下cpp文件：native-lib.cpp

#include 
#include 
extern "C" {

#include 
#include 
#include 

JNIEXPORT jstring JNICALL
Java_com_xxx_svsdk_tools_FFMpegUtils_avcodecinfo(JNIEnv *env, jobject instance) {

    char info[40000] = {0};
    av_register_all();
    AVCodec *c_temp = av_codec_next(NULL);
    while (c_temp != NULL) {
        if (c_temp->decode != NULL) {
            sprintf(info, "%sdecode:", info);
        } else {
            sprintf(info, "%sencode:", info);
        }
        switch (c_temp->type) {
            case AVMEDIA_TYPE_VIDEO:
                sprintf(info, "%s(video):", info);
                break;
            case AVMEDIA_TYPE_AUDIO:
                sprintf(info, "%s(audio):", info);
                break;
            default:
                sprintf(info, "%s(other):", info);
                break;
        }
        sprintf(info, "%s[%10s]\n", info, c_temp->name);
        c_temp = c_temp->next;
    }
    return env->NewStringUTF(info);
}

extern "C"
jstring
Java_com_xxx_svsdk_tools_FFMpegUtils_stringFromJNI(
        JNIEnv *env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}

}

然后就是新建一个java类，来导入native方法了

image.png

package com.xxx.svsdk.tools;

/**
 * Created by dengxuan on 17-9-8.
 */

public class FFMpegUtils {
    public static native String stringFromJNI();

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

然后就可以新建个activity来测试导入的方法了

@Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.sample_activity);
        textView = (TextView) findViewById(R.id.textview);
        textView.append(FFMpegUtils.stringFromJNI()+"\n"+FFMpegUtils.avcodecinfo());
    }

运行：

image.png

7.将FFMpeg集成到新的android工程。新建android工程，选中include c++ support

image.png

在工程目录下新建libs文件夹把刚才第五步中生成的android目录下的文件拷贝过来。

image.png

8.打开app目录下的 CMakeLists.txt 写入如下配置：

# Sets the minimum version of CMake required to build the native
# library. You should either keep the default value or only pass a
# value of 3.4.0 or lower.

cmake_minimum_required(VERSION 3.4.1)

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 )

set(distribution_DIR ${CMAKE_SOURCE_DIR}/../../../../libs)

add_library( avutil-55
             SHARED
             IMPORTED )
set_target_properties( avutil-55
                       PROPERTIES IMPORTED_LOCATION
                       ../../../../libs/armeabi-v7a/libavutil-55.so )

add_library( swresample-2
             SHARED
             IMPORTED )
set_target_properties( swresample-2
                       PROPERTIES IMPORTED_LOCATION
                       ../../../../libs/armeabi-v7a/libswresample-2.so )
add_library( avcodec-57
             SHARED
             IMPORTED )
set_target_properties( avcodec-57
                       PROPERTIES IMPORTED_LOCATION
                       ../../../../libs/armeabi-v7a/libavcodec-57.so )
add_library( avfilter-6
             SHARED
             IMPORTED)
set_target_properties( avfilter-6
                       PROPERTIES IMPORTED_LOCATION
                       ../../../../libs/armeabi-v7a/libavfilter-6.so )
add_library( swscale-4
             SHARED
             IMPORTED)
set_target_properties( swscale-4
                       PROPERTIES IMPORTED_LOCATION
                       ../../../../libs/armeabi-v7a/libswscale-4.so )

add_library( avformat-57
             SHARED
             IMPORTED)
set_target_properties( avformat-57
                       PROPERTIES IMPORTED_LOCATION
                       ../../../../libs/armeabi-v7a/libavformat-57.so )



set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++11")

add_library( native-lib
             SHARED
             src/main/cpp/native-lib.cpp
              )

include_directories(libs/include)

#target_include_directories(native-lib PRIVATE libs/include)

target_link_libraries( native-lib swresample-2 avcodec-57 avfilter-6 swscale-4 avformat-57
                       ${log-lib} )

编辑配置build.gralde文件

android {
 ......
    defaultConfig {
        ....
        ndk {
            abiFilters 'armeabi-v7a'
        }
    }

    sourceSets {
        main {
            jniLibs.srcDirs = ['libs']
        }
    }
}

编写Activity

public class MainActivity extends Activity {

    private TextView textView;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        textView = new TextView(this);
        setContentView(textView);
        textView.setText(stringFromJNI());
    }

    public native String stringFromJNI();

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

}

在src/main/cpp/native-lib.cpp编写C++代码：

#include 
#include 
extern "C" {

#include 
#include 
#include 

JNIEXPORT jstring JNICALL
Java_com_dx_myffmpeg_MainActivity_avcodecinfo(JNIEnv *env, jobject instance) {

    char info[40000] = {0};
    av_register_all();
    AVCodec *c_temp = av_codec_next(NULL);
    while (c_temp != NULL) {
        if (c_temp->decode != NULL) {
            sprintf(info, "%sdecode:", info);
        } else {
            sprintf(info, "%sencode:", info);
        }
        switch (c_temp->type) {
            case AVMEDIA_TYPE_VIDEO:
                sprintf(info, "%s(video):", info);
                break;
            case AVMEDIA_TYPE_AUDIO:
                sprintf(info, "%s(audio):", info);
                break;
            default:
                sprintf(info, "%s(other):", info);
                break;
        }
        sprintf(info, "%s[%10s]\n", info, c_temp->name);
        c_temp = c_temp->next;
    }
    return env->NewStringUTF(info);
}

extern "C"
jstring
Java_com_dx_myffmpeg_MainActivity_stringFromJNI(
        JNIEnv *env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}
}

注意两个native方法前面的路径 “com_dx_myffmpeg” 需要改成MainActivity对应的package下！
然后就可以运行程序了：

image.png

[1].FFMpeg入门之 - Android集成FFMpeg

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