ffmpegyuv数据采集

1.打开视频设备

static AVFormatContext* open_dev()
{int ret &＃61; 0;char errors[1024] &＃61;{0,};AVFormatContext *fmt_ctx &＃61; NULL;AVDictionary *options&＃61; NULL;//0:0 前面的0是视频设备&＃xff0c;后面的0是音频设备&＃xff0c;这里只采集视频//0 是机器摄像头//1 是桌面char * devicename &＃61; "0";//av_register_all();// 1.注册所有的编解码器和音视频格式avdevice_register_all();//2.选取mac对应的avfoundation库//mac 上使用avfoundation&＃xff0c;windows上面使用directshow&＃xff0c;linux使用alsaAVInputFormat *iformat &＃61; av_find_input_format("avfoundation");//video_size 指定分辨率的大小av_dict_set(&options,"video_size","640x480", 0);av_dict_set(&options,"framerate","30", 0);av_dict_set(&options,"pixel_format","nv12", 0);//av_dict_set(&options,"list_devices","true",0);//打开设备上下文ret &＃61; avformat_open_input(&fmt_ctx, devicename, iformat,&options);if(ret < 0){av_strerror(ret, errors, 1024);fprintf(stderr, "Failed to open device,[%d]%s\n",ret,errors);return NULL;}return fmt_ctx;
}&＃96;在这里插入代码片&＃96;


2.yuv数据采集

void rec_video()
{int ret &＃61; 0;AVFormatContext *fmt_ctx &＃61; NULL;AVPacket pkt;av_log_set_level(AV_LOG_DEBUG);rec_status &＃61; 1;char *out &＃61;"/users/test/Downloads/video.yuv";FILE * outfile &＃61; fopen(out,"wb&＃43;");fmt_ctx &＃61; open_dev();if(NULL &＃61;&＃61; fmt_ctx){av_log(NULL, AV_LOG_DEBUG, "&＃61;&＃61;&＃61;&＃61;&＃61;ERROR&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;!\n");goto __ERROR;}av_log(NULL, AV_LOG_DEBUG, "test 11111111!\n");while(rec_status){ret &＃61; av_read_frame(fmt_ctx, &pkt);if (ret &＃61;&＃61; 0){ // 读取成功// 将数据写入文件//&＃xff08;宽x高&＃xff09;x&＃xff08;yuv420&＃61;1.5/yuv422&＃61;2/yuv444&＃61;3&＃xff09;字节//fwrite的第三个形参长度是以为字节为单位的//nv12是yuv420的一种存储格式fwrite(pkt.data,1,460800, outfile);// 释放资源&＃xff0c;此处必须释放&＃xff0c;每次av_read_frame都会增加引用计数&＃xff0c;av_packet_unref释放引用计数&＃xff0c;等到引用计数为0的时候&＃xff0c;资源被释放av_packet_unref(&pkt);}else if (ret &＃61;&＃61; AVERROR(EAGAIN)){ // 资源临时不可用//此处会引起cpu占用率过高continue;}else{ // 其他错误//errbuf[1024];//av_strerror(ret, errbuf, sizeof (errbuf));//av_log(NULL, AV_LOG_INFO, "errbuf is %s \n",errbuf);break;}// 必须要加&＃xff0c;释放pkt内部的资源av_packet_unref(&pkt);}__ERROR:if(outfile){fclose(outfile);}if(fmt_ctx){avformat_close_input(&fmt_ctx);}av_log(NULL, AV_LOG_DEBUG, "finish!\n");return;
}


播放&＃xff1a;
ffplay -pix_fmt nv12 -s 640x480 video.yuv
不指定格式时&＃xff0c;播放出来的时黑白色的&＃xff0c;估计是默认的格式