使用ffmpeg x264进行编码的时候，avcodec_open报错：
[libx264 @ 00021bb0]broken ffmpeg default settings detected
[libx264 @ 00021bb0]use an encoding preset (vpre)

解决方法：在 x264 的source file encoder/encoder.c 中找到该报错的地方
/* Detect default ffmpeg settings and terminate with an error. */
    {
        int score = 0;
        score += h->param.analyse.i_me_range == 0;
        score += h->param.rc.i_qp_step == 3;
        score += h->param.i_keyint_max == 12;
        score += h->param.rc.i_qp_min == 2;
        score += h->param.rc.i_qp_max == 31;
        score += h->param.rc.f_qcompress == 0.5;
        score += fabs(h->param.rc.f_ip_factor - 1.25) < 0.01;
        score += fabs(h->param.rc.f_pb_factor - 1.25) < 0.01;
        score += h->param.analyse.inter == 0 && h->param.analyse.i_subpel_refine == 8;
        if( score >= 5 )
        {
            x264_log( h, X264_LOG_ERROR, "broken ffmpeg default settings detected\n" );
            x264_log( h, X264_LOG_ERROR, "use an encoding preset (vpre)\n" );
            return -1;
        }
    }
 
We can see that if score >= 5,the function to open the codec will fail.
We must at least set 4 param of the AVCodecContext before open it.
在avcodec_open函数之间增加如下几个AVCodecContext 的初始化：
/*default settings for x264*/
        ctx->me_range = 16;
        ctx->max_qdiff = 4;
        ctx->qmin = 10;
        ctx->qmax = 51;
        ctx->qcompress = 0.6; 

上面几个参数设置下，不能大于等于5，否则就会出错。
我这里设置如下：

  pCodecCtx->qmin =3;

  pCodecCtx->qmax =30;

  pCodecCtx->qcompress =1;