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5. 完成XThread线程类IDemux继承后在线程中读取帧数据~1

发布时间：2021-06-09 11:10:34编辑：雪饮阅读（）

 用线程去读取帧数据，首先要在CMakeLists.txt中配置线程cpp

# 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 3.10.2)

# Declares and names the project.

project("xplay")

# 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.
#添加頭文件路徑(括號中的include是相對於本文件路徑)
include_directories(../../../include)
#設置ffmpeg庫所在路徑的變量，這裏的FF是自定義的一個名字
set(FF ${CMAKE_CURRENT_SOURCE_DIR}/../../../libs/${ANDROID_ABI})
#avcodec這個是自定義的一個名字
add_library(avcodec SHARED IMPORTED)
set_target_properties(avcodec PROPERTIES IMPORTED_LOCATION ${FF}/libavcodec.so)

add_library(avformat SHARED IMPORTED)
set_target_properties(avformat PROPERTIES IMPORTED_LOCATION ${FF}/libavformat.so)

add_library(avutil SHARED IMPORTED)
set_target_properties(avutil PROPERTIES IMPORTED_LOCATION ${FF}/libavutil.so)

add_library(swscale SHARED IMPORTED)
set_target_properties(swscale PROPERTIES IMPORTED_LOCATION ${FF}/libswscale.so)

add_library(swresample SHARED IMPORTED)
set_target_properties(swresample PROPERTIES IMPORTED_LOCATION ${FF}/libswresample.so)
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
            IDemux
            FFDemux
            XData
            XLog
            native-lib.cpp
            XThread
        )

# 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
                       GLESv2 EGL
                       OpenSLES
                       android
                       avcodec avformat avutil swscale swresample
                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib} )
然后实现线程cpp: XThread.cpp:

#include "XThread.h"
#include "XLog.h"

#include <thread>
using namespace std;

//启动线程
void XThread::Start()
{
    thread th(&XThread::ThreadMain,this);
    th.detach();
}
void XThread::ThreadMain()
{
    XLOGI("线程函数进入");
    Main();
    XLOGI("线程函数退出");
}


//通过控制isExit安全停止线程（不一定成功）
void XThread::Stop()
{

}

以及线程头文件: XThread.h: #ifndef XPLAY_XTHREAD_H
#define XPLAY_XTHREAD_H

//c++ 11 线程库
class XThread
{
public:
    //启动线程
    virtual void Start();

    //通过控制isExit安全停止线程（不一定成功）
    virtual void Stop();

    //入口主函数
    virtual void Main() {}

private:
    void ThreadMain();

};


#endif //XPLAY_XTHREAD_H

然后要对待使用线程的类定义一个main方法：IDemux.cpp： #include "IDemux.h"
#include "XLog.h"

void IDemux::Main()
{
    for(;;)
    {
        XData d = Read();
        XLOGI("IDemux Read %d",d.size);
        if(d.size<=0)break;
    }
}

头文件IDemux.h中自是必不可少： #ifndef XPLAY_IDEMUX_H
#define XPLAY_IDEMUX_H

#include "XData.h"
#include "XThread.h"
//解封装接口
class IDemux:public XThread{
public:
    //打开文件，或者流媒体 rmtp http rtsp
    virtual bool Open(const char *url) = 0;

    //读取一帧数据，数据由调用者清理
    virtual XData Read() = 0;
    //总时长（毫秒）
    int totalMs = 0;
protected:
    virtual void Main();
};


#endif //XPLAY_IDEMUX_H

然后在入口cpp中测试线程的开启：native-lib.cpp： #include <jni.h>
#include <string>
#include "FFDemux.h"
#include "XLog.h"
extern "C" JNIEXPORT jstring JNICALL
Java_com_example_xplay_MainActivity_stringFromJNI(
        JNIEnv* env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    IDemux *de = new FFDemux();
    de->Open("/sdcard/1080.mp4");
    de->Start();
    /*
    for(;;)
    {
        XData d = de->Read();
        XLOGI("Read data size is %d",d.size);


    }
    */
    return env->NewStringUTF(hello.c_str());
}

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