opencv 摄像头视频 ffmpeg保存H264

opencv无法使用Tcp实时传输摄像头视频，而UDP容易引起丢帧卡顿现象，所以，必须借助ffmpeg来缓存摄像头视频

#ifndef INT64_C 
 #define INT64_C(c) (c ## LL) 
 #define UINT64_C(c) (c ## ULL) 
 #endif extern "C" {
     /*Include ffmpeg header file*/
 #include <libavformat/avformat.h> 
 #include <libavcodec/avcodec.h> 
 #include <libswscale/swscale.h> #include <libavutil/imgutils.h>  
 #include <libavutil/opt.h>     
 #include <libavutil/mathematics.h>   
 #include <libavutil/samplefmt.h>
 }int main()
 {
     //变量
     AVFormatContext *pFormatCtx;
     char filepath[] = "rtsp://admin:admin@192.168.1.13:554/video2";
     AVPacket *packet;
     //初始化
     av_register_all();
     avformat_network_init();
     pFormatCtx = avformat_alloc_context();
     AVDictionary* options = NULL;
     av_dict_set(&options, "buffer_size", "102400", 0); //设置缓存大小，1080p可将值调大
     av_dict_set(&options, "rtsp_transport", "tcp", 0); //以udp方式打开，如果以tcp方式打开将udp替换为tcp
     av_dict_set(&options, "stimeout", "2000000", 0); //设置超时断开连接时间，单位微秒
     av_dict_set(&options, "max_delay", "500000", 0); //设置最大时延
     packet = (AVPacket *)av_malloc(sizeof(AVPacket));
     //打开网络流或文件流  
     if (avformat_open_input(&pFormatCtx, filepath, NULL, &options) != 0)    
     {
         printf("Couldn't open input stream.\n");
         return -1;
     }
     //查找码流信息
     //设置查找时间以避免耗时过长
     pFormatCtx->probesize = 1000;
     pFormatCtx->max_analyze_duration = AV_TIME_BASE;
     if (avformat_find_stream_info(pFormatCtx, NULL)<0)
     {
         printf("Couldn't find stream information.\n");
         return -1;
     }
     //查找码流中是否有视频流
     int videoindex = -1;
     for (int 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.\n");
         return -1;
     }
     //保存一段时间的视频流，写入文件中
     FILE *fpSave;
     fpSave=fopen("geth264.h264", "wb");
     for (int i = 0; i < 1000; i++)
     {  
         if (av_read_frame(pFormatCtx, packet) >= 0)
         {
             if (packet->stream_index == videoindex)
             {
                 fwrite(packet->data, 1, packet->size, fpSave);//写数据到文件中  
             }
             av_packet_unref(packet);
         }
     }
     //释放内存
     fclose(fpSave);
     av_free(pFormatCtx);
     av_free(packet);
     return 0;
 }

需安装ffmpeg 之后，再编译

-I/monchickey/ffmpeg/include -L/monchickey/ffmpeg/lib -lavformat -lavcodec -lavutil

具体安装的库路径自己判断哦