【來自】

1.新建XCode工程後，發現即使安裝了SDL和FFMPEG也編譯不成功，需要修改各種環境。經過我的不懈努力加百穀啥的...貼個能編譯通過的過程出來。謹記！

2.首先需要編譯好ffmpeg原始碼，然後還需要安裝SDL（ffmpeg直接編譯，SDL我是通過brew安裝的）

3.修改工程的搜尋路徑，Header search Path新增ffmpeg的include目錄以及/usr/local/include目錄，告知Xcode需要使用的FFMPEG以及SDL標頭檔案的路徑，Library search path則是對應的FFMPEG以及SDL的庫目錄

4.新增其他引用庫以及框架，如下圖所示：

5.基本不用改的程式碼如下：

/**
 * 最簡單的基於FFmpeg的視訊播放器
 * Simplest FFmpeg Player
 *
 * 雷霄驊 Lei Xiaohua
 * [email protected]
 * 中國傳媒大學/數字電視技術
 * Communication University of China / Digital TV Technology
 * http://blog.csdn.net/leixiaohua1020
 *
 * 本程式實現了視訊檔案的解碼和顯示（支援HEVC，H.264，MPEG2等）。
 * 是最簡單的FFmpeg視訊解碼方面的教程。
 * 通過學習本例子可以瞭解FFmpeg的解碼流程。
 * This software is a simplest video player based on FFmpeg.
 * Suitable for beginner of FFmpeg.
 *
 * Version:1.0
 */


extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "sdl/SDL.h"
#include "sdl/SDL_thread.h"
};

//Full Screen
#define SHOW_FULLSCREEN 0
//Output YUV420P
#define OUTPUT_YUV420P 0

int main(int argc, char* argv[])
{
    
    AVFormatContext	*pFormatCtx;
    int				i, videoindex;
    AVCodecContext	*pCodecCtx;
    AVCodec			*pCodec;
    char filepath[]="/Users/wangwei/src/1.mkv";
    av_register_all();
    avformat_network_init();
    pFormatCtx = avformat_alloc_context();
    
    if(avformat_open_input(&pFormatCtx,filepath,NULL,NULL)!=0){
        printf("Couldn't open input stream.（無法開啟輸入流）\n");
        return -1;
    }
    if(avformat_find_stream_info(pFormatCtx, NULL) < 0)
    {
        printf("Couldn't find stream information.（無法獲取流資訊）\n");
        return -1;
    }
    videoindex=-1;
    for(i=0; i<pFormatCtx->nb_streams; i++)
        if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
        {
            videoindex=i;
            break;
        }
    if(videoindex==-1)
    {
        printf("Didn't find a video stream.（沒有找到視訊流）\n");
        return -1;
    }
    pCodecCtx=pFormatCtx->streams[videoindex]->codec;
    pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
    if(pCodec==NULL)
    {
        printf("Codec not found.（沒有找到解碼器）\n");
        return -1;
    }
    if(avcodec_open2(pCodecCtx, pCodec,NULL)<0)
    {
        printf("Could not open codec.（無法開啟解碼器）\n");
        return -1;
    }
    AVFrame	*pFrame,*pFrameYUV;
    pFrame=avcodec_alloc_frame();
    pFrameYUV=avcodec_alloc_frame();
    uint8_t *out_buffer=(uint8_t *)av_malloc(avpicture_get_size(PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height));
    avpicture_fill((AVPicture *)pFrameYUV, out_buffer, PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);
    //------------SDL----------------
    if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
        printf( "Could not initialize SDL - %s\n", SDL_GetError());
        return -1;
    }
    
    int screen_w=0,screen_h=0;
    SDL_Surface *screen;
#if SHOW_FULLSCREEN
    const SDL_VideoInfo *vi = SDL_GetVideoInfo();
    screen_w = vi->current_w;
    screen_h = vi->current_h;
    screen = SDL_SetVideoMode(screen_w, screen_h, 0,SDL_FULLSCREEN);
#else
    screen_w = pCodecCtx->width;
    screen_h = pCodecCtx->height;
    screen = SDL_SetVideoMode(screen_w, screen_h, 0,0);
#endif
    
    if(!screen) {
        printf("SDL: could not set video mode - exiting:%s\n",SDL_GetError());
        return -1;
    }
    SDL_Overlay *bmp;
    bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height,SDL_YV12_OVERLAY, screen);
    SDL_Rect rect;
    
    int ret, got_picture;
    
    AVPacket *packet=(AVPacket *)av_malloc(sizeof(AVPacket));
    //輸出一下資訊-----------------------------
    printf("File Information（檔案資訊）---------------------\n");
    av_dump_format(pFormatCtx,0,filepath,0);
    printf("-------------------------------------------------\n");
    
#if OUTPUT_YUV420P
    FILE *fp_yuv=fopen("output.yuv","wb+");
#endif
    
    
    struct SwsContext *img_convert_ctx;
    img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
    //------------------------------
    while(av_read_frame(pFormatCtx, packet)>=0)
    {
        if(packet->stream_index==videoindex)
        {
            ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
            if(ret < 0)
            {
                printf("Decode Error.（解碼錯誤）\n");
                return -1;
            }
            if(got_picture)
            {
                sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
                
#if OUTPUT_YUV420P
                int y_size=pCodecCtx->width*pCodecCtx->height;
                fwrite(pFrameYUV->data[0],1,y_size,fp_yuv);    //Y
                fwrite(pFrameYUV->data[1],1,y_size/4,fp_yuv);  //U
                fwrite(pFrameYUV->data[2],1,y_size/4,fp_yuv);  //V
#endif
                SDL_LockYUVOverlay(bmp);
                bmp->pixels[0]=pFrameYUV->data[0];
                bmp->pixels[2]=pFrameYUV->data[1];
                bmp->pixels[1]=pFrameYUV->data[2];
                bmp->pitches[0]=pFrameYUV->linesize[0];
                bmp->pitches[2]=pFrameYUV->linesize[1];
                bmp->pitches[1]=pFrameYUV->linesize[2];
                SDL_UnlockYUVOverlay(bmp); 
                rect.x = 0;    
                rect.y = 0;    
                rect.w = screen_w;    
                rect.h = screen_h;  
                //測試自己填充資料----------------
                SDL_DisplayYUVOverlay(bmp, &rect); 
                //延時40ms
                //SDL_Delay(40);
            }
        }
        av_free_packet(packet);
    }
    sws_freeContext(img_convert_ctx);
    
#if OUTPUT_YUV420P 
    fclose(fp_yuv);
#endif 
    
    SDL_Quit();
    
    av_free(out_buffer);
    av_free(pFrameYUV);
    avcodec_close(pCodecCtx);
    avformat_close_input(&pFormatCtx);
    
    return 0;
}