NSString *path = [[NSBundle mainBundle] pathForResource:@"nwn" ofType:@"mp4"];

    const char *filepath= [path UTF8String];

    av_register_all();

    avformat_network_init();

    pFormatCtx = avformat_alloc_context();

    if(avformat_open_input(&pFormatCtx,filepath,NULL,NULL)!=){

        printf("Couldn't open input stream.\n");

        exit();

    }

    /*

     * av_find_stream_info()：ffmpeg版本更新后没有这个函数了，用avformat_find_stream_info这个函数，可以自己看一下版本更新改动

     */

    //    if(av_find_stream_info(pFormatCtx)<0)

    if(avformat_find_stream_info(pFormatCtx, NULL) < )

    {

        printf("Couldn't find stream information.\n");

        exit();

    }

    videoindex=-;

    for(int i=; i<pFormatCtx->nb_streams; i++)

        if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)

        {

            videoindex=i;

            break;

        }

    if(videoindex==-)

    {

        printf("Didn't find a video stream.\n");

        exit();

    }

    pCodecCtx=pFormatCtx->streams[videoindex]->codec;

    pCodec=avcodec_find_decoder(pCodecCtx->codec_id);

    if(pCodec==NULL)

    {

        printf("Codec not found.\n");

        exit();

    }

    /*

     * avcodec_open()：ffmpeg版本更新后没有这个函数了，用avformat_find_stream_info这个函数，可以自己看一下版本更新改动

     * avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)

     */

    //    if(avcodec_open(pCodecCtx, pCodec)<0)

    if(avcodec_open2(pCodecCtx, pCodec, NULL)<)

    {

        printf("Could not open codec.\n");

        exit();

    }

    AVFrame    *pFrame,*pFrameYUV;

    pFrame=avcodec_alloc_frame();

    pFrameYUV=avcodec_alloc_frame();

    uint8_t *out_buffer;

    out_buffer=new uint8_t[avpicture_get_size(PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height)];

    avpicture_fill((AVPicture *)pFrameYUV, out_buffer, PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);

    int ret, got_picture;

    int y_size = pCodecCtx->width * pCodecCtx->height;

    AVPacket *packet=(AVPacket *)malloc(sizeof(AVPacket));

    av_new_packet(packet, y_size);

    printf("video infomation：\n");

    av_dump_format(pFormatCtx,,filepath,);

    while(av_read_frame(pFormatCtx, packet)>=)

    {

        if(packet->stream_index==videoindex)

        {

            ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);

            if(ret < )

            {

                printf("Decode Error.\n");

                exit();

            }

            if(got_picture)

            {

                char *buf = (char *)malloc(pFrame->width * pFrame->height *  / );

                AVPicture *pict;

                int w, h;

                char *y, *u, *v;

                pict = (AVPicture *)pFrame;//这里的frame就是解码出来的AVFrame

                w = pFrame->width;

                h = pFrame->height;

                y = buf;

                u = y + w * h;

                v = u + w * h / ;

                for (int i=; i<h; i++)

                    memcpy(y + w * i, pict->data[] + pict->linesize[] * i, w);

                for (int i=; i<h/; i++)

                    memcpy(u + w /  * i, pict->data[] + pict->linesize[] * i, w / );

                for (int i=; i<h/; i++)

                    memcpy(v + w /  * i, pict->data[] + pict->linesize[] * i, w / );

                [myview setVideoSize:pFrame->width height:pFrame->height];

                [myview displayYUV420pData:buf width:pFrame->width height:pFrame->height]; //利用OpenGLES渲染YUV

                free(buf);

            }

        }

        av_free_packet(packet);

    }

    delete[] out_buffer;

    av_free(pFrameYUV);

    avcodec_close(pCodecCtx);

    avformat_close_input(&pFormatCtx);