ffmpeg学习（三）——ffmpeg+SDL2 实现简单播放器

本篇实现基于ffmpeg动态库用测试程序播放本地文件和RTSP视频流。

参考文章：http://blog.csdn.net/leixiaohua1020/article/details/8652605，

http://blog.csdn.net/guanghua2_0beta/article/details/37578299

创建工程，参考上一篇文章：http://www.cnblogs.com/wenjingu/p/3990071.html，注意：下载SDL2库的开发版，lib文件放到lib文件夹下，dll放到debug文件夹下。

代码如下，在参考文章的基础上做了少量改动，主要是将ffmpeg老版本的部分函数在替换为2.4版本中的新函数。

#include "stdafx.h"

#ifdef __cplusplus
extern "C" {
#endif

#include <libavcodec/avcodec.h>
#include <libavdevice/avdevice.h>
#include <libavformat/avformat.h>
#include <libavfilter/avfilter.h>
#include <libavutil/avutil.h>
#include <libswscale/swscale.h>
#include <SDL2/SDL.h>

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>

#ifdef __cplusplus
}
#endif

int ffplayer()
{
    AVFormatContext    *pFormatCtx;
    int                i, videoindex;
    AVCodecContext    *pCodecCtx;
    AVCodec            *pCodec;
    //char filepath[]="F:\\Work\\ffmpegdemo\\Debug\\Wildlife.wmv";
    char rtspUrl[] = "rtsp://admin:[email protected]:554";
    av_register_all();//注册组件
    avformat_network_init();//支持网络流
    pFormatCtx = avformat_alloc_context();//初始化AVFormatContext
    if(avformat_open_input(&pFormatCtx,/*filepath*/rtspUrl,NULL,NULL)!=0){//打开文件或网络流
        printf("无法打开文件\n");
        return -1;
    }
    if(avformat_find_stream_info(pFormatCtx, NULL)<0)//查找流信息
    {
        printf("Couldn‘t find stream information.\n");
        return -1;
    }
    videoindex=-1;
    for(i=0; i<pFormatCtx->nb_streams; i++) //获取视频流ID
        if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
        {
            videoindex=i;
            break;
        }
    if(videoindex==-1)
    {
        printf("Didn‘t find a video stream.\n");
        return -1;
    }
    pCodecCtx=pFormatCtx->streams[videoindex]->codec;
    pCodec=avcodec_find_decoder(pCodecCtx->codec_id);//查找解码器
    if(pCodec==NULL)
    {
        printf("Codec not found.\n");
        return -1;
    }
    if(avcodec_open2(pCodecCtx, pCodec, NULL)<0)//打开解码器
    {
        printf("Could not open codec.\n");
        return -1;
    }
    AVFrame    *pFrame,*pFrameYUV;
    pFrame=avcodec_alloc_frame();//存储解码后AVFrame
    pFrameYUV=avcodec_alloc_frame();//存储转换后AVFrame
    uint8_t *out_buffer;
    out_buffer=new uint8_t[avpicture_get_size(PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height)];//分配AVFrame所需内存
    avpicture_fill((AVPicture *)pFrameYUV, out_buffer, PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);//填充AVFrame

    //------------SDL初始化--------
    if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
        printf( "Could not initialize SDL - %s\n", SDL_GetError());
        return -1;
    }
    SDL_Window *screen = SDL_CreateWindow("RTSP Client Demo",
                          SDL_WINDOWPOS_UNDEFINED,
                          SDL_WINDOWPOS_UNDEFINED,
                          pCodecCtx->width, pCodecCtx->height,
                          SDL_WINDOW_RESIZABLE/* SDL_WINDOW_HIDDEN*/| SDL_WINDOW_OPENGL);
    if(!screen) {
        printf("SDL: could not set video mode - exiting\n");
        return -1;
    }
    SDL_Renderer* sdlRenderer = SDL_CreateRenderer(screen, -1, 0);
    SDL_Texture* sdlTexture = SDL_CreateTexture(
        sdlRenderer,
        SDL_PIXELFORMAT_YV12,
        SDL_TEXTUREACCESS_STREAMING,
        pCodecCtx->width,
        pCodecCtx->height); 

    SDL_Rect rect;
    //-----------------------------
    int ret, got_picture;
    static struct SwsContext *img_convert_ctx;
    int y_size = pCodecCtx->width * pCodecCtx->height;

    SDL_Event event;
    AVPacket *packet=(AVPacket *)malloc(sizeof(AVPacket));//存储解码前数据包AVPacket
    av_new_packet(packet, y_size);
    //输出一下信息-----------------------------
    printf("文件信息-----------------------------------------\n");
    //av_dump_format(pFormatCtx,0,filepath,0);
    printf("-------------------------------------------------\n");
    //------------------------------
    while(av_read_frame(pFormatCtx, packet)>=0)//循环获取压缩数据包AVPacket
    {
        if(packet->stream_index==videoindex)
        {
            ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);//解码。输入为AVPacket，输出为AVFrame
            if(ret < 0)
            {
                printf("解码错误\n");
                return -1;
            }
            if(got_picture)
            {
                //像素格式转换。pFrame转换为pFrameYUV。
                img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
                sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
                sws_freeContext(img_convert_ctx);
                //------------SDL显示--------
                rect.x = 0;
                rect.y = 0;
                rect.w = pCodecCtx->width;
                rect.h = pCodecCtx->height;    

                SDL_UpdateTexture( sdlTexture, &rect, pFrameYUV->data[0], pFrameYUV->linesize[0] );
                SDL_RenderClear( sdlRenderer );
                SDL_RenderCopy( sdlRenderer, sdlTexture, &rect, &rect );
                SDL_RenderPresent( sdlRenderer );
                //延时20ms
                SDL_Delay(20);
                //------------SDL-----------
            }
        }
        av_free_packet(packet);
        SDL_PollEvent(&event);
        switch( event.type ) {
            case SDL_QUIT:
                SDL_Quit();
                exit(0);
                break;
            default:
                break;
        }
    }

    SDL_DestroyTexture(sdlTexture);
    delete[] out_buffer;
    av_free(pFrameYUV);
    avcodec_close(pCodecCtx);
    avformat_close_input(&pFormatCtx);

    return 0;
}

int _tmain(int argc, _TCHAR* argv[])
{
    ffplayer();

    return 0;
}

测试效果：

播放rtsp网络流

也可以播放本地文件，将rtspUrl替换为filepath即可。