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OpenCV版本

• OpenCV 4.1.2

视频编码

• h264视频编码参考代码，outputVideo.write(frame) 需要有视频raw数据；

#include 
   
    #include 
    
     int main(){    // init    cv::VideoWriter outputVideo;    cv::Size S = cv::Size(width_output, height_output);    int fourcc = cv::VideoWriter::fourcc('H','2','6','4');    int fps = 25;    outputVideo.open(output_file, fourcc, fps, S);        // write frame    outputVideo.write(frame);        // deinit    outputVideo.release();        return 0;    }
    
   

h264视频编码参数调整

• 修改文件 master/modules/videoio/src/cap_ffmpeg_impl.hpp

#if LIBAVUTIL_BUILD > CALC_FFMPEG_VERSION(51,11,0)    /* Some settings for libx264 encoding, restore dummy values for gop_size     and qmin since they will be set to reasonable defaults by the libx264     preset system. Also, use a crf encode with the default quality rating,     this seems easier than finding an appropriate default bitrate. */    if (c->codec_id == AV_CODEC_ID_H264) {      c->gop_size = -1;      c->qmin = -1;      c->bit_rate = 0;      if (c->priv_data)          av_opt_set(c->priv_data,"crf","21", 0);          av_opt_set(c->priv_data,"preset","faster", 0);    }#endif

上面的代码，修改了crf参数，23修改为21

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