FFmpeg+SDL（雷神）-（4-进阶）

(4) SDL视频显示-进阶
代码记录

---

#include 

extern "C"
{
#include "sdl/SDL.h"
};

const int bpp=12;

int screen_w=500,screen_h=500;
const int pixel_w=320,pixel_h=180;

unsigned char buffer[pixel_w*pixel_h*bpp/8];

//Refresh Event
#define REFRESH_EVENT  (SDL_USEREVENT + 1)
//Break
#define BREAK_EVENT  (SDL_USEREVENT + 2)

int thread_exit=0;
int thread_pause=0;

int refresh_video(void *opaque){
    thread_exit=0;
    while (thread_exit==0) {
        if(thread_pause==0){
        SDL_Event event;
        event.type = REFRESH_EVENT;
        SDL_PushEvent(&event);
        }
        SDL_Delay(40);
    }
    thread_exit=0;
    //Break
    SDL_Event event;
    event.type = BREAK_EVENT;
    SDL_PushEvent(&event);
    return 0;
}

int writeY(FILE *i_file,FILE *o_file,const int w,const int h){
    //读取文件i_file
    FILE* fp_yuv=i_file;
    //写入文件o_file
    FILE* fp_frame=o_file;
    //开辟内存，与读取的文件的大小一致
    char* buffer_y=(char*)malloc(sizeof(char)*w*h);
    char* buffer_u=(char*)malloc(sizeof(char)*w*h/4);
    char* buffer_v=(char*)malloc(sizeof(char)*w*h/4);
    //读取函数，将i_file的第一帧存入buff指向的内存
    for(int i=0;i<50;i++)//50：i_file文件一共有50帧
    {
        fread(buffer_y,w*h,1,fp_yuv);
        fread(buffer_u,w*h/4,1,fp_yuv);
        fread(buffer_v,w*h/4,1,fp_yuv);
        /*memset():将buffer_u/buffer_v后面的w*h/4个字节用128替换*/
        memset(buffer_u,128,w*h/4);//128：色度的值，取值0~255
        memset(buffer_v,128,w*h/4);//128：饱和度的值，取值0~255
        fwrite(buffer_y,w*h,1,fp_frame);
        fwrite(buffer_u,w*h/4,1,fp_frame);
        fwrite(buffer_v,w*h/4,1,fp_frame);
    }
    free(buffer_y);
    free(buffer_u);
    free(buffer_v);
    return 0;
}

int main(int argc, char* argv[])
{
    if(SDL_Init(SDL_INIT_VIDEO)) {  
        printf( "Could not initialize SDL - %s\n", SDL_GetError()); 
        return -1;
    } 

    SDL_Window *screen; 
    //SDL 2.0 Support for multiple windows
    screen = SDL_CreateWindow("Simplest Video Play SDL2", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
        screen_w, screen_h,SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
    if(!screen) {  
        printf("SDL: could not create window - exiting:%s\n",SDL_GetError());  
        return -1;
    }
    SDL_Renderer* sdlRenderer = SDL_CreateRenderer(screen, -1, 0);  

    Uint32 pixformat=0;
    //IYUV: Y + U + V  (3 planes)
    //YV12: Y + V + U  (3 planes)
    pixformat= SDL_PIXELFORMAT_IYUV;  

    SDL_Texture* sdlTexture = SDL_CreateTexture(sdlRenderer,pixformat, SDL_TEXTUREACCESS_STREAMING,pixel_w,pixel_h);

    FILE *fp=NULL;
    fp=fopen("test_yuv420p_320x180.yuv","rb+");
    if(fp==NULL){
        printf("cannot open this file\n");
        return -1;
    }

    //写入文件frame.yuv（亮度数据）
    FILE* fp_frame=fopen("frame_320x180_out.yuv","wb");
    writeY(fp,fp_frame,pixel_w,pixel_h);
    fclose(fp_frame);

    SDL_Rect sdlRect;  

    SDL_Thread *refresh_thread = SDL_CreateThread(refresh_video,NULL,NULL);
    SDL_Event event;
    while(1){
        //Wait
        SDL_WaitEvent(&event);
        if(event.type==REFRESH_EVENT){
            if (fread(buffer, 1, pixel_w*pixel_h*bpp/8, fp) != pixel_w*pixel_h*bpp/8){
                // Loop
                fseek(fp, 0, SEEK_SET);
                fread(buffer, 1, pixel_w*pixel_h*bpp/8, fp);
            }

            SDL_UpdateTexture( sdlTexture, NULL, buffer, pixel_w);  

            //FIX: If window is resize
            sdlRect.x = 0;  
            sdlRect.y = 0;  
            sdlRect.w = screen_w;  
            sdlRect.h = screen_h;  
            
            SDL_RenderClear( sdlRenderer );   
            SDL_RenderCopy( sdlRenderer, sdlTexture, NULL, &sdlRect);  
            SDL_RenderPresent( sdlRenderer ); 
            
        }else if(event.type==SDL_WINDOWEVENT){
            //If Resize
            SDL_GetWindowSize(screen,&screen_w,&screen_h);
        }else if(event.type==SDL_KEYDOWN){
            //Pause
            if(event.key.keysym.sym==SDLK_SPACE)
                thread_pause=!thread_pause;
        }else if(event.type==SDL_QUIT){
            thread_exit=1;
        }else if(event.type==BREAK_EVENT){
            break;
        }
    }
    SDL_Quit();
    return 0;
}