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\n");
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\n", hours, mins, secs, (100 * us) / AV_TIME_BASE);
}

i = 0;
int videostream = -1;
printf("pFormatCtx->nb_streams=%d\n", 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\n", videostream);

if (-1 == videostream)
{
printf("error no video stream\n");
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\n");
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\n");
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\n", 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\n", 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\n",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\n", 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\n");
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\n", 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\n", f1);
printf("f2=%d\n", f2);

return 0;
}