根據前文所說yolo代碼邏輯：

├── examples
│   ├── darknet.c(主程序)
│   │── xxx1.c
│   └── xxx2.c
│
├── include
│   ├── darknet.h
│ 
│ 
├── Makefile
│ 
│ 
└── src
    ├── yyy1.c
    ├── yyy2.h
    └──......

視頻檢測入口時darknet.c文件。

輸入視頻檢測命令，如： ./darknet detector demo cfg/coco.data cfg/yolov3.cfg yolov3.weights ~/dataset/ca3.mp4

run_detector函數內容如下

void run_detector(int argc, char **argv)
{
    char *prefix = find_char_arg(argc, argv, "-prefix", 0);
    float thresh = find_float_arg(argc, argv, "-thresh", .5);
    float hier_thresh = find_float_arg(argc, argv, "
 
-hier", .5);
    int cam_index = find_int_arg(argc, argv, "-c", 0);
    int frame_skip = find_int_arg(argc, argv, "-s", 0);
    int avg = find_int_arg(argc, argv, "-avg", 3);
    if(argc < 4){
        fprintf(stderr, "usage: %s %s [train/test/valid] [cfg] [weights (optional)]\n", argv[0], argv[1]);
        
 
return;
    }
    char *gpu_list = find_char_arg(argc, argv, "-gpus", 0);
    char *outfile = find_char_arg(argc, argv, "-out", 0);
    int *gpus = 0;
    int gpu = 0;
    int ngpus = 0;
    if(gpu_list){
        printf("%s\n", gpu_list);
        int len = strlen(gpu_list);
        ngpus = 1;
        int i;
        for(i = 0; i < len; ++i){
            if (gpu_list[i] == ‘,‘) ++ngpus;
        }
        gpus = calloc(ngpus, sizeof(int));
        for(i = 0; i < ngpus; ++i){
            gpus[i] = atoi(gpu_list);
            gpu_list = strchr(gpu_list, ‘,‘)+1;
        }
    } else {
        gpu = gpu_index;
        gpus = &gpu;
        ngpus = 1;
    }

    int clear = find_arg(argc, argv, "-clear");
    int fullscreen = find_arg(argc, argv, "-fullscreen");
    int width = find_int_arg(argc, argv, "-w", 0);
    int height = find_int_arg(argc, argv, "-h", 0);
    int fps = find_int_arg(argc, argv, "-fps", 0);
    //int class = find_int_arg(argc, argv, "-class", 0);

代碼中定義了frame_skip等變量，默認值為0.然後繼續調用demo函數，demo函數位於/darknet/src/demo.c文件中，內容如下。

void demo(char *cfgfile, char *weightfile, float thresh, int cam_index, const char *filename, char **names, int classes, int delay, char *prefix, int avg_frames, float hier, int w, int h, int frames, int fullscreen)
{
    //demo_frame = avg_frames;
    image **alphabet = load_alphabet();
    demo_names = names;
    demo_alphabet = alphabet;
    demo_classes = classes;
    demo_thresh = thresh;
    demo_hier = hier;
    printf("Demo\n");
    net = load_network(cfgfile, weightfile, 0);
    set_batch_network(net, 1);
    pthread_t detect_thread;
    pthread_t fetch_thread;

    srand(2222222);

    int i;
    demo_total = size_network(net);
    predictions = calloc(demo_frame, sizeof(float*));
    for (i = 0; i < demo_frame; ++i){
        predictions[i] = calloc(demo_total, sizeof(float));
    }
    avg = calloc(demo_total, sizeof(float));

    if(filename){
        printf("video file: %s\n", filename);
        cap = open_video_stream(filename, 0, 0, 0, 0);
    }else{
        cap = open_video_stream(0, cam_index, w, h, frames);
    }

    if(!cap) error("Couldn‘t connect to webcam.\n");

    buff[0] = get_image_from_stream(cap);
    buff[1] = copy_image(buff[0]);
    buff[2] = copy_image(buff[0]);
    buff_letter[0] = letterbox_image(buff[0], net->w, net->h);
    buff_letter[1] = letterbox_image(buff[0], net->w, net->h);
    buff_letter[2] = letterbox_image(buff[0], net->w, net->h);

    int count = 0;
    if(!prefix){
        make_window("Demo", 1352, 1013, fullscreen);
    }

    demo_time = what_time_is_it_now();

    while(!demo_done){
        buff_index = (buff_index + 1) %3;
        if(pthread_create(&fetch_thread, 0, fetch_in_thread, 0)) error("Thread creation failed");
        if(pthread_create(&detect_thread, 0, detect_in_thread, 0)) error("Thread creation failed");
        if(!prefix){
            fps = 1./(what_time_is_it_now() - demo_time);
            demo_time = what_time_is_it_now();
            display_in_thread(0);
        }else{
            char name[256];
            sprintf(name, "%s_%08d", prefix, count);
            save_image(buff[(buff_index + 1)%3], name);
        }
        pthread_join(fetch_thread, 0);
        pthread_join(detect_thread, 0);
        ++count;
    }
}

yolo遠嗎解析（3）：視頻檢測流程