C++-ffmpeg-2-1-RGB-YUV内存中的存储+SDL2对其渲染

1.RGB和YUV在内存中如何存储
2.SDL2渲染RGB
3.SDL2渲染YUV

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1.RGB和YUV在内存中如何存储
   RGB存储的方式：
   

 读取RGB的代码：

void TestRGB::paintEvent(QPaintEvent* ev)
{
    //1.QImage 存放RGB矩阵  后面专业术语叫材质
    QImage img(w,h,QImage::Format_RGB888);
    auto d = img.bits();
    unsigned char r = 255;
    for (int j = 0; j < h; j++)
    {
        r--;
        int b = j * w * 3;
        for (int i = 0; i < w * 3; i+=3)
        {
            d[b+i] = r;       //R
            d[b + i + 1] = 0;   //G
            d[b + i + 2] = 0;   //B
        }
    }
    //2.QPainter 显示RGB矩阵  后面专业术语叫渲染器
    QPainter p;
    p.begin(this);
    p.drawImage(0, 0, img);
    p.end();
}

  YUV格式是不被显卡显示的，要转换成RGB.是用软件把YUV文件转换成RGB软件的。
2.SDL2渲染RGB
   2.1，安装和配置SDL2的环境。简单的下载包，配置dll,lib,include三个路径入工程。
   2.2, 2个词 ：渲染器(一个窗口),材质(用于承载图像) 。还有一个内存数组用于存放RGBA的数据，可把这个内存数据写入材质中。
基本的使用流程如下：

 代码如下：

 

#include 
#include 
using namespace std;
#pragma comment(lib,"SDL2.lib")
#undef main
int main(int argc, char* argv[])
{
    int w = 800;
    int h = 600;
    //1 初始化SDL video库
    if (SDL_Init(SDL_INIT_VIDEO))
    {
        cout << SDL_GetError() << endl;
        return -1;
    }
    //2 生成SDL 窗口
    auto screen = SDL_CreateWindow("test sdl ffmpeg",
        SDL_WINDOWPOS_CENTERED,//窗口位置
        SDL_WINDOWPOS_CENTERED,
        w,h,
        SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE
    );
    if (!screen)
    {
        cout << SDL_GetError() << endl;
        return -2;
    }
 
    //3 生成渲染器
    auto render = SDL_CreateRenderer(screen, -1, SDL_RENDERER_ACCELERATED);
    if (!render)
    {
        cout << SDL_GetError() << endl;
        return -3;
    }
    //4 生成材质
    auto texture = SDL_CreateTexture(render, SDL_PIXELFORMAT_ARGB8888,
        SDL_TEXTUREACCESS_STREAMING,// 可加锁
        w, h
    );
    if (!texture)
    {
        cout << SDL_GetError() << endl;
        return -4;
    }
 
    // 存放图像的数据
    shared_ptr<unsigned char> rgb(new unsigned char[w * h * 4]);
    auto r = rgb.get();
    unsigned char tmp = 255;
    for (;;)
    {
        //判断退出
        SDL_Event ev;
        SDL_WaitEventTimeout(&ev, 10);
        if (ev.type == SDL_QUIT)
        {
            SDL_DestroyWindow(screen);
            break;
        }
        tmp--;
    
        for (int j = 0; j < h; j++)
        {
            int b = j * w * 4;
            for (int i = 0; i < w*4; i += 4)
            {
                r[b + i] = 0;           //B
                r[b + i + 1] = 0;       //G
                r[b + i + 2] = tmp;     //R
                r[b + i + 3] = 0;       //A
            }
        }
        //5 内存数据写入材质
        SDL_UpdateTexture(texture, NULL, r, w * 4);
 
        //6 清理屏幕
        SDL_RenderClear(render);
        SDL_Rect sdl_rect;
        sdl_rect.x = 0;
        sdl_rect.y = 0;
        sdl_rect.w = w;
        sdl_rect.h = h;
    
        //7 复制材质到渲染器
        SDL_RenderCopy(render, texture,
            NULL,//原图位置和尺寸
            &sdl_rect//目标位置和尺寸
        );
        //8 渲染
        SDL_RenderPresent(render);
    }
    getchar();
    return 0;
}

以上就是基本函数。
定时刷新的就是材质中的rgb值，具体就是
SDL_UpdateTexture(sdl_texture, NULL, rgb, sdl_width * pix_size);
3.SDL2渲染YUVYUV格式分析:

4个像素点共享1个UV 实心代表亮度，空心的代表色度。

 代码如下：
这个版本已经是定时刷新屏幕了。

#include "sdlqtrgb.h"
#include 
#include 
#include 
using namespace std;
#pragma comment(lib,"SDL2.lib")
static SDL_Window* sdl_win = NULL;
static SDL_Renderer* sdl_render = NULL;
static SDL_Texture* sdl_texture = NULL;
static int sdl_width = 0;
static int sdl_height = 0;
static unsigned  char* yuv = NULL;
static int pix_size = 2;
static ifstream yuv_file;
void SdlQtRGB::timerEvent(QTimerEvent* ev)
{
    yuv_file.read((char*)yuv, sdl_width * sdl_height * 1.5);
    //yuv 平面存储存储
    // yyyyyyyy uu vv
    SDL_UpdateTexture(sdl_texture, NULL, yuv, 
        sdl_width  //一行 y的字节数
    );
    SDL_RenderClear(sdl_render);
    SDL_Rect rect;
    rect.x = 0;
    rect.y = 0;
    rect.w = sdl_width;
    rect.h = sdl_height;
    SDL_RenderCopy(sdl_render,sdl_texture,NULL,&rect);
    SDL_RenderPresent(sdl_render);
}
 
SdlQtRGB::SdlQtRGB(QWidget *parent)
    : QWidget(parent)
{
    //打开yuv文件
    yuv_file.open("400_300_25.yuv", ios::binary);
    if (!yuv_file)
    {
        QMessageBox::information(this, "", "open yuv failed!");
        return;
    }
    ui.setupUi(this);
    sdl_width = 400; 
    sdl_height = 300;
    ui.label->resize(sdl_width, sdl_height);
    //初始化SDL
    SDL_Init(SDL_INIT_VIDEO);
    //创建窗口
    sdl_win = SDL_CreateWindowFrom((void*)ui.label->winId());
    //创建渲染器
    sdl_render = SDL_CreateRenderer(sdl_win, -1, SDL_RENDERER_ACCELERATED);
    //创建材质 支持YUV
    sdl_texture = SDL_CreateTexture(sdl_render,
        SDL_PIXELFORMAT_IYUV,
        SDL_TEXTUREACCESS_STREAMING,
        sdl_width,
        sdl_height
    );
    yuv = new unsigned char[sdl_width * sdl_height * pix_size];
    startTimer(10);
}