1、准备个Linux系统,用来编译FFmpeg源码
给Linux安装NDK
ndk下载地址:https://developer.android.google.cn/ndk/downloads/index.html
解压NDK,并配置环境变量
ffmpeg下载地址:http://www.ffmpeg.org/download.html
下载后放入Linux目录:/usr/etc/android,这是我用的地址,读者可根据自己需要更换
然后解压出来。
修改 FFmpeg 的 configure
由于FFMPEG默认编译出来的动态库文件名的版本号在.so之后(例如“libavcodec.so.5.100.1”),但是android平台不能识别这样文件名,所以我们需要修改FFMPEG生成的动态库的文件名。
打开 configure 文件,找到:
SLIBNAME_WITH_MAJOR='$(SLIBNAME).$(LIBMAJOR)'
LIB_INSTALL_EXTRA_CMD='$$(RANLIB)"$(LIBDIR)/$(LIBNAME)"'
SLIB_INSTALL_NAME='$(SLIBNAME_WITH_VERSION)'
SLIB_INSTALL_LINKS='$(SLIBNAME_WITH_MAJOR)$(SLIBNAME)'
修改为:
SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(FULLNAME)-$(LIBMAJOR)$(SLIBSUF)'
LIB_INSTALL_EXTRA_CMD='$$(RANLIB)"$(LIBDIR)/$(LIBNAME)"'
SLIB_INSTALL_NAME='$(SLIBNAME_WITH_MAJOR)'
SLIB_INSTALL_LINKS='$(SLIBNAME)'
创建编译脚本build4anroid.sh,注意在Linux上用vi创建,如果在windows上创建 执行时会出错,脚本内容如下:
#!/bin/sh
NDK=/usr/etc/android/android-ndk-r12b
SYSROOT=$NDK/platforms/android-23/arch-arm/
TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64
CPU=arm
PREFIX=./android/$CPU
ADDI_CFLAGS="-marm"
config_para()
{
./configure \
--prefix=$PREFIX \
--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
}
config_para
然后执行编译,编译过程中有可能遇到某个文件没有权限的问题,修改下权限即可
编译会花费一段时间,完成后会在android/arm文件夹下生成库文件,include里是头文件,lib里是so库文件
新建Android项目,勾选C++。
把上面生成的so库放入Android项目libs/armeabi下,把include整个文件夹放入libs目录下,文件结构如下:
修改build.gradle,具体如下:
修改CMakeLists.txt,具体内容如下:
# 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.
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
# Links the target library to the log library
# included in the NDK.
${log-lib} )
set(distribution_DIR ../../../../libs)
add_library( avcodec-57
SHARED
IMPORTED)
set_target_properties( avcodec-57
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/armeabi/libavcodec-57.so)
add_library( avfilter-6
SHARED
IMPORTED)
set_target_properties( avfilter-6
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/armeabi/libavfilter-6.so)
add_library( avformat-57
SHARED
IMPORTED)
set_target_properties( avformat-57
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/armeabi/libavformat-57.so)
add_library( avutil-55
SHARED
IMPORTED)
set_target_properties( avutil-55
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/armeabi/libavutil-55.so)
add_library( swresample-2
SHARED
IMPORTED)
set_target_properties( swresample-2
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/armeabi/libswresample-2.so)
add_library( swscale-4
SHARED
IMPORTED)
set_target_properties( swscale-4
PROPERTIES IMPORTED_LOCATION
${distribution_DIR}/armeabi/libswscale-4.so)
include_directories(libs/include)
target_link_libraries( # Specifies the target library.
native-lib
avcodec-57
avfilter-6
avformat-57
avutil-55
swresample-2
swscale-4
# Links the target library to the log library
# included in the NDK.
${log-lib}
)
修改C++代码native-lib.cpp,具体内容如下:
#include <jni.h>
#include <string>
#include <android/log.h>
extern "C" {
//编码
#include "libavcodec/avcodec.h"
//封装格式处理
#include "libavformat/avformat.h"
//像素处理
#include "libswscale/swscale.h"
}
#define FFLOGI(FORMAT,...) __android_log_print(ANDROID_LOG_INFO,"ffmpeg",FORMAT,##__VA_ARGS__);
#define FFLOGE(FORMAT,...) __android_log_print(ANDROID_LOG_ERROR,"ffmpeg",FORMAT,##__VA_ARGS__);
extern "C"
JNIEXPORT jstring JNICALL
Java_com_sheng_example_jnitest_MainActivity_stringFromJNI(
JNIEnv *env,
jobject /* this */) {
std::string hello = "Hello from C++";
char info[40000] = { 0 };
av_register_all();
AVInputFormat *if_temp = av_iformat_next(NULL);
AVOutputFormat *of_temp = av_oformat_next(NULL);
//Input
while(if_temp!=NULL){
sprintf(info, "%s[In ][%10s]\n", info, if_temp->name);
if_temp=if_temp->next;
}
//Output
while (of_temp != NULL){
sprintf(info, "%s[Out][%10s]\n", info, of_temp->name);
of_temp = of_temp->next;
}
// return env->NewStringUTF(hello.c_str());
return env->NewStringUTF(info);
}
/**
* com.leixiaohua1020.sffmpegandroidhelloworld.MainActivity.avformatinfo()
* AVFormat Support Information
*/
extern "C"
JNIEXPORT jstring JNICALL
Java_com_sheng_example_jnitest_MainActivity_avformatinfo(JNIEnv *env, jobject obj){
char info[40000] = { 0 };
av_register_all();
AVInputFormat *if_temp = av_iformat_next(NULL);
AVOutputFormat *of_temp = av_oformat_next(NULL);
//Input
while(if_temp!=NULL){
sprintf(info, "%s[In ][%10s]\n", info, if_temp->name);
if_temp=if_temp->next;
}
//Output
while (of_temp != NULL){
sprintf(info, "%s[Out][%10s]\n", info, of_temp->name);
of_temp = of_temp->next;
}
FFLOGI("%s", info);
return env->NewStringUTF(info);
}
由于是简单测试,就直接在MainActivity上加载so库了
MainActivity代码如下:
package com.sheng.example.jnitest;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
// Used to load the 'native-lib' library on application startup.
static {
System.loadLibrary("native-lib");
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Example of a call to a native method
TextView tv = (TextView) findViewById(R.id.sample_text);
tv.setText(avformatinfo());
}
/**
* A native method that is implemented by the 'native-lib' native library,
* which is packaged with this application.
*/
public native String stringFromJNI();
public native String avformatinfo();
}
编译运行APP后 就能看到主界面上出来FFmpeg所支持的编码格式了。