SDL2常用代码

作者: 何亮hook_8285 | 来源:发表于2022-12-04 22:49 被阅读0次

SDL2渲染YUV420P数据

提取YUV420P：ffmpeg -i a.mp4 -pix_fmt yuv420p a.yuv

方式一

#include <iostream>
#include <fstream>
#include <memory.h>
#include <SDL2/SDL.h>
#undef main
//heliang
int main()
{
    int w=1364;
    int h=768;
    //打开yuv文件
    std::ifstream yuv_file;
    yuv_file.open("D:\\ds.yuv",std::ios::binary);

    //初始化SDL
    SDL_Init(SDL_INIT_VIDEO);
    //创建窗口
    SDL_Window *sdl_win=SDL_CreateWindow("test",
                                         SDL_WINDOWPOS_CENTERED,SDL_WINDOWPOS_CENTERED,w,h,
                                         SDL_WindowFlags::SDL_WINDOW_OPENGL| SDL_WINDOW_RESIZABLE);
    //如果想绑定到QT的Widget元素中，可使用SDL_CreateWindowFrom函数
    //sdl_win=SDL_CreateWindowFrom((void*)this->ui->centralwidget->winId());

    //创建渲染器
    SDL_Renderer *sdl_rend=SDL_CreateRenderer(sdl_win,-1,SDL_RENDERER_ACCELERATED);
    //创建材质
    SDL_Texture *sdl_text=SDL_CreateTexture(sdl_rend,          SDL_PIXELFORMAT_IYUV,SDL_TEXTUREACCESS_STREAMING,w,h);



    while(yuv_file.good())
    {
        //读取yuv文件，按照y分量，u分量，v分量读取
        int lenY=w*h;
        int lenU=w*h/4;
        int lenV=w*h/4;
        unsigned char *pYBuf = (unsigned char *)malloc(lenY);
        unsigned char *pUBuf = (unsigned char *)malloc(lenU);
        unsigned char *pVBuf = (unsigned char *)malloc(lenV);

        yuv_file.read((char*)pYBuf,lenY);
        yuv_file.read((char*)pUBuf,lenU);
        yuv_file.read((char*)pVBuf,lenV);

        SDL_Rect  rect;
        rect.x=0;
        rect.y=0;
        rect.w=w;
        rect.h=h;
        //更新材质
        SDL_UpdateYUVTexture(sdl_text, &rect, pYBuf, w, pUBuf, w / 2, pVBuf, w / 2);
        //清除渲染器
        SDL_RenderClear(sdl_rend);
        //材质和渲染器绑定
        SDL_RenderCopy(sdl_rend,sdl_text,NULL,NULL);
        //渲染器图像显示到显示器
        SDL_RenderPresent(sdl_rend);
        //销毁数据
        free(pYBuf);
        free(pUBuf);
        free(pVBuf);
    }



    //销毁材质(纹理)
    SDL_DestroyTexture(sdl_text);
    //销毁创建
    SDL_DestroyWindow(sdl_win);
    SDL_Quit();
}

方式二


#include <iostream>
#include <fstream>
#include <memory.h>
#include <SDL2/SDL.h>
#undef main
//heliang
int main()
{
    int w=1364;
    int h=768;
    //打开yuv文件
    std::ifstream yuv_file;
    yuv_file.open("D:\\ds.yuv",std::ios::binary);

    //初始化SDL
    SDL_Init(SDL_INIT_VIDEO);
    //创建窗口
    SDL_Window *sdl_win=SDL_CreateWindow("test",
                                         SDL_WINDOWPOS_CENTERED,SDL_WINDOWPOS_CENTERED,w,h,
                                         SDL_WindowFlags::SDL_WINDOW_OPENGL| SDL_WINDOW_RESIZABLE);
    //如果想绑定到QT的Widget元素中，可使用SDL_CreateWindowFrom函数
    //sdl_win=SDL_CreateWindowFrom((void*)this->ui->centralwidget->winId());

    //创建渲染器
    SDL_Renderer *sdl_rend=SDL_CreateRenderer(sdl_win,-1,SDL_RENDERER_ACCELERATED);
    //创建材质(纹理)
    SDL_Texture *sdl_text=SDL_CreateTexture(sdl_rend,          SDL_PIXELFORMAT_IYUV,SDL_TEXTUREACCESS_STREAMING,w,h);




    while(yuv_file.good())
    {
        //读取1帧数据
        unsigned char * yuvData=(unsigned char *)malloc(w*h*2);
        yuv_file.read((char*)yuvData,w*h*1.5);

        SDL_Rect rect;
        rect.x = 0;
        rect.y = 0;
        rect.w = w;
        rect.h = h;
        //更新材质(纹理)
        SDL_UpdateTexture(sdl_text, NULL, yuvData, w);
        //清除渲染器
        SDL_RenderClear(sdl_rend);
        //材质和渲染器绑定
        SDL_RenderCopy(sdl_rend,sdl_text,NULL,NULL);
        //渲染器图像显示到显示器
        SDL_RenderPresent(sdl_rend);
        //销毁数据
        free(yuvData);
    }



    //销毁材质(纹理)
    SDL_DestroyTexture(sdl_text);
    //销毁创建
    SDL_DestroyWindow(sdl_win);
    SDL_Quit();

    return 0;
}

SDL2渲染RGBA数据


#include <iostream>
#include <fstream>
#include <memory.h>
#include <SDL2/SDL.h>
#undef main
//heliang
int main()
{
    int w=1364;
    int h=768;
    int pix_size=4;

    //初始化SDL
    SDL_Init(SDL_INIT_VIDEO);
    //创建窗口
    SDL_Window *sdl_win=SDL_CreateWindow("test",
                                         SDL_WINDOWPOS_CENTERED,SDL_WINDOWPOS_CENTERED,w,h,
                                         SDL_WindowFlags::SDL_WINDOW_OPENGL| SDL_WINDOW_RESIZABLE);
    //如果想绑定到QT的Widget元素中，可使用SDL_CreateWindowFrom函数
    //sdl_win=SDL_CreateWindowFrom((void*)this->ui->centralwidget->winId());

    //创建渲染器
    SDL_Renderer *sdl_rend=SDL_CreateRenderer(sdl_win,-1,SDL_RENDERER_ACCELERATED);
    //创建材质(纹理)
    SDL_Texture *sdl_text=SDL_CreateTexture(sdl_rend,SDL_PIXELFORMAT_ARGB8888,SDL_TEXTUREACCESS_STREAMING,w,h);

    unsigned char tempcount=255;
    bool  flag=true;
    while(flag)
    {
        //事件结构体 
        SDL_Event  ev;
        //获取事件
        SDL_WaitEventTimeout(&ev,10);
        //按下鼠标则退出
        if(ev.type==SDL_MOUSEBUTTONDOWN)
        {
            flag=false;
            break;
        }
        //生成一帧RGBA数据
        unsigned char * rgbaData=(unsigned char *)malloc(w*h*pix_size);
        for(int i=0;i<h;i++)
        {
            //高*宽*字节数=当前行宽度
            int b=i*w*pix_size;
            for(int j=0;j<w*pix_size;j+=pix_size)
            {
                rgbaData[b+j]=0;//B
                rgbaData[b+j+1]=211;  //G
                rgbaData[b+j+2]=tempcount; //R
                rgbaData[b+j+3]=0; //A

            }
        }


        //更新材质
        SDL_UpdateTexture(sdl_text, NULL, rgbaData, w*pix_size);
        //清除渲染器
        SDL_RenderClear(sdl_rend);
        //材质和渲染器绑定
        SDL_RenderCopy(sdl_rend,sdl_text,NULL,NULL);
        //渲染器图像显示到显示器
        SDL_RenderPresent(sdl_rend);
        //销毁数据
        free(rgbaData);

        tempcount--;
    }

    //销毁材质(纹理)
    SDL_DestroyTexture(sdl_text);
    //销毁创建
    SDL_DestroyWindow(sdl_win);
    SDL_Quit();

    return 0;
}

SDL2播放PCM音频

// 提取PCM文件
// ffmpeg -i input.mp4 -t 20 -codec:a pcm_s16le -ar 44100 -ac 2 -f s16le 44100_16bit_2ch.pcm
// 测试PCM文件
// ffplay -ar 44100 -ac 2 -f s16le 44100_16bit_2ch.pcm



#include <iostream>
#include <memory.h>
#include <SDL2/SDL.h>
#undef main


//每次读取2帧数据，以1024采样点一帧2通道 16bit采样点为例
#define PCM_BUFFER_SIZE (1024*2*2*2)

//读取PCM数据缓存
static  unsigned char * audioBuf=NULL;
//目前读取的位置
static  unsigned char * audioPos=NULL;
//缓存结束的位置
static  unsigned char * audioEnd=NULL;

//音频回调方法
void sdl_AudioCallback (void *userdata, Uint8 * stream,int len)
{
    SDL_memset(stream,0,len);
    if(audioPos>=audioEnd) //数据读取完成
    {
        return;
    }

    // 数据够了就读预设长度，数据不够就只读部分（不够的时候剩多少就读取多少）
    int remain_buffer_len = audioEnd - audioPos;
    len = (len < remain_buffer_len) ? len : remain_buffer_len;
    // 拷贝数据到stream并调整音量
    SDL_MixAudio(stream, audioPos, len, SDL_MIX_MAXVOLUME);

    std::cout << "len=" << len << std::endl;
    audioPos += len;  // 移动缓存指针
}

//heliang
int main()
{

    //初始化SDL 音频
    SDL_Init(SDL_INIT_AUDIO);

    //设置音频参数
    SDL_AudioSpec spec;
    spec.freq=44100; //采样频率
    spec.format=AUDIO_S16SYS; //采样点格式
    spec.channels=2; //通道
    spec.silence=0; //音频缓冲静音值
    spec.samples=1024; //每次读取的采样率数量,多久产生一次回调
    spec.callback=sdl_AudioCallback; //回调方法
    spec.userdata=NULL;

    //打开音频设备
    if(SDL_OpenAudio(&spec,NULL))
    {
        std::cout << "open audio device error" <<std::endl;
        return 0;
    }

    //播放音频
    SDL_PauseAudio(0);

    FILE *pcmFP=fopen("d:\\BaiduNetdiskDownload\\44100_16bit_2ch.pcm","rb");
    //初始化buff
    audioBuf=(unsigned char *)malloc(PCM_BUFFER_SIZE);

    while(true)
    {

        //读取文件内容
        int readBufferLen=fread(audioBuf,1,PCM_BUFFER_SIZE,pcmFP);
        //读取长度等于0，表示未读取到内容
        if(readBufferLen==0)
        {
            break;
        }

        audioEnd=audioBuf+readBufferLen; // 更新buffer的结束位置
        audioPos=audioBuf;// 更新buffer的起始位置
        while(audioPos<audioEnd)
        {
            SDL_Delay(10);  // 等待PCM数据消耗
        }
    }
    //关闭pcm文件句柄
    fclose(pcmFP);
    //销毁内存数据
    free(audioBuf);
    // 关闭音频设备
    SDL_CloseAudio();
    //退出SDL
    SDL_Quit();
}

SDL2常用代码

SDL2渲染YUV420P数据

方式一

方式二

SDL2渲染RGBA数据

SDL2播放PCM音频

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