简单播放器（增加sdl事件控制）

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <stdio.h>
#include <SDL2/SDL.h>
#include <time.h>

#define SFM_REFRESH_EVENT  (SDL_USEREVENT + 1)

int thread_exit=0;
//Thread
int sfp_refresh_thread(void *opaque)
{
    SDL_Event event;
    while (thread_exit==0) {
        event.type = SFM_REFRESH_EVENT;
        SDL_PushEvent(&event);
        //Wait 40 ms
        SDL_Delay(15);
    }
    return 0;
}

int main(int argc, char* argv[])
{
    AVFormatContext    *pFormatCtx;//格式上下文结构体
    int                i, videoindex;
    AVCodecContext    *pCodecCtx;//codec上下文
    AVCodec            *pCodec;//codec
    
    int screen_w=0,screen_h=0;  
    SDL_Window *screen;   
    SDL_Renderer* sdlRenderer;  
    SDL_Texture* sdlTexture;  
    SDL_Rect sdlRect;
    SDL_Thread *video_tid;
    SDL_Event event;
    
    av_register_all();//ffmpeg flow 0,注册codec
    avformat_network_init();//如要打开网络流，必须运行此函数
    pFormatCtx = avformat_alloc_context();//格式上下文结构体指针开空间
    if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL) != 0)//打开多媒体文件
    {
        printf("open file error
");
        return -1;
    }

    AVDictionary* pOptions = NULL;
    if ( avformat_find_stream_info(pFormatCtx, &pOptions) < 0 )//读取音视频数据相关信息，参数0：上下文结构体指针，参数1：option  
    {
        return -1;
    }
    av_dump_format(pFormatCtx, 0, argv[1], 0);//调试函数，输出文件的音、视频流的基本信息

    //获取视频的时长
    if(pFormatCtx->duration != AV_NOPTS_VALUE)
    {  
        int hours, mins, secs, us;  
        int64_t duration = pFormatCtx->duration + 5000;  
        secs = duration / AV_TIME_BASE;  
        us = duration % AV_TIME_BASE;  
        mins = secs / 60;  
        secs %= 60;  
        hours = mins/ 60;  
        mins %= 60;  
        printf("%02d:%02d:%02d.%02d
", hours, mins, secs, (100 * us) / AV_TIME_BASE);  
    } 



    i = 0;
    int videostream = -1;
    printf("pFormatCtx->nb_streams=%d
", pFormatCtx->nb_streams);
    for(i=0;i<pFormatCtx->nb_streams;i++)//遍历多媒体文件中的每一个流，判断是否为视频。
    {
        if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
        {
            videostream = i;
            break;
        }
    }
    printf("videostream=%d
", videostream);
    
    if (-1 == videostream)
    {
        printf("error no video stream
");
        return;
    }

    pCodecCtx = pFormatCtx->streams[videostream]->codec;//codec上下文指定到格式上下文中的codec

    
    pCodec = avcodec_find_decoder( pCodecCtx->codec_id );//找到一个codec，必须先调用av_register_all（）
    
    if(NULL == pCodec)
    {
        printf("couldn't find the decode
");
        return -1;
    }
    
    if( avcodec_open2(pCodecCtx, pCodec, NULL) < 0)//初始化一个视音频编解码器的AVCodecContext
    {
        printf("open decode error
");
        return -1;
    }

    AVFrame    *pFrame,*pFrameYUV;//Frame结构体
    pFrame = av_frame_alloc();//原始帧
    pFrameYUV = av_frame_alloc();//YUV帧
    uint8_t *out_buffer;

    int num = avpicture_get_size(AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);
    printf("num=%d
", num);


    out_buffer = (uint8_t *)av_malloc(num*sizeof(uint8_t));
    avpicture_fill((AVPicture *)pFrameYUV, out_buffer, AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);//将pFrameYUV和out_buffer联系起来（pFrame指向一段内存）


    AVPacket packet;//packet结构体
    int ret = -1;
    i = 0;
    struct SwsContext *img_convert_ctx = NULL;//图像格式转化上下文 
    img_convert_ctx = sws_getContext(pCodecCtx->width,pCodecCtx->height,pCodecCtx->pix_fmt , pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);//初始化SWS，图片格式转化上下文
    
    if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) 
    {    
        printf( "Could not initialize SDL - %s
", SDL_GetError());   
        return -1;  
    }
    
    screen_w = pCodecCtx->width;  
    screen_h = pCodecCtx->height;  
    //SDL 2.0 Support for multiple windows  
    screen = SDL_CreateWindow("Simplest ffmpeg player's Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,  
        screen_w, screen_h,  
        SDL_WINDOW_OPENGL);

  
    if(!screen) 
    {    
        printf("SDL: could not create window - exiting:%s
",SDL_GetError());    
        return -1;  
    }
    
    sdlRenderer = SDL_CreateRenderer(screen, -1, 0);
    sdlTexture = SDL_CreateTexture(sdlRenderer, SDL_PIXELFORMAT_IYUV, SDL_TEXTUREACCESS_STREAMING,pCodecCtx->width,pCodecCtx->height);    
    sdlRect.x=0;  
    sdlRect.y=0;  
    sdlRect.w=screen_w;  
    sdlRect.h=screen_h;
    
    int f1 = 0;
    int f2 = 0;
    int got_picture = -1;

    video_tid = SDL_CreateThread(sfp_refresh_thread,NULL,NULL);
    time_t t;
    time(&t);
    printf("begin :%s
", ctime(&t));

    while (1) 
    {
        SDL_WaitEvent(&event);
        if(event.type==SFM_REFRESH_EVENT)
        {
            if(av_read_frame(pFormatCtx, &packet)>=0)//读取码流中的音频若干帧或者视频一帧,作为packet
            {
                f1++;
                if(packet.stream_index == videostream)//如果是视频
                {
                    ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, &packet);//解码一帧视频数据。输入一个压缩编码的结构体AVPacket，输出一个解码后的结构体AVFrame
        
                    if(ret < 0)
                    {
                        printf("decode error
");
                        return -1;
                    }
            
                    if(got_picture)
                    {
                            //转换
                        sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 
                                    0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);//将输出结果转化成YUV
                
                        SDL_UpdateYUVTexture(sdlTexture, &sdlRect,  
                        pFrameYUV->data[0], pFrameYUV->linesize[0],  
                        pFrameYUV->data[1], pFrameYUV->linesize[1],  
                        pFrameYUV->data[2], pFrameYUV->linesize[2]);  
                
                        SDL_RenderClear( sdlRenderer );    
                        SDL_RenderCopy( sdlRenderer, sdlTexture,  NULL, &sdlRect);   
                        SDL_RenderPresent( sdlRenderer );
                
                        //SDL_Delay(40);

                        f2++;

                    }
                }             

                av_free_packet(&packet);
            }
            else
            {
                thread_exit=1;
                break;
            }
        }

    }

    time(&t);
    printf("begin :%s
", ctime(&t));

    SDL_Quit();

    sws_freeContext(img_convert_ctx);

     free(out_buffer);
    av_free(pFrameYUV);

    // Free the YUV frame
    av_free(pFrame);

    // Close the codec
    avcodec_close(pCodecCtx);

    // Close the video file
    avformat_close_input(&pFormatCtx);

    printf("f1=%d
", f1);
    printf("f2=%d
", f2);

    return 0;
}