Your yolov5 🚀 Is it limited to detect py？ If other programs want to call yolov5, you need to make a detect python API for python. python has objects everywhere. Making the detect API is actually making the detect class.

preface

yolov5 Source code version: as of 2022.2.3
 Link: https://github.com/ultralytics/yolov5

As a "CV" advocate, I haven't found the appropriate API code on all platforms before. There is a good article https://www.pythonheidong.com/blog/article/851830/44a42d351037d307d02d/
Unfortunately, the code version is too "old", and some functions are no longer applicable. This paper makes and detect in a simple and rough way Py API with the same function. Even if the source code is updated, I can quickly make an API for other programs to call according to my method.

1, General idea

Other programs call yolo, which is actually transmitting the image to detect py. To maximize detection For all the functions of Py, the most direct way is to store the frame image in the 'date/images' directory by the camera or video stream, and then read the frame image from' runs/detect/exp '. This method increases processing time, but the delay in actually storing and reading images is very low, even on raspberry pie.

2, Make detect class

In detect PY

class DetectAPI:
    def __init__(self, weights='weights/yolov5s.pt', data='data/coco128.yaml', imgsz=None, conf_thres=0.25,
                 iou_thres=0.45, max_det=1000, device='0', view_img=False, save_txt=False,
                 save_conf=False, save_crop=False, nosave=False, classes=None, agnostic_nms=False, augment=False,
                 visualize=False, update=False, project='runs/detect', name='myexp', exist_ok=False, line_thickness=3,
                 hide_labels=False, hide_conf=False, half=False, dnn=False):

        if imgsz is None:
            self.imgsz = [640, 640]
        self.weights = weights
        self.data = data
        self.source = 'data/myimages'
        self.imgsz = [640, 640]
        self.conf_thres = conf_thres
        self.iou_thres = iou_thres
        self.max_det = max_det
        self.device = device
        self.view_img = view_img
        self.save_txt = save_txt
        self.save_conf = save_conf
        self.save_crop = save_crop
        self.nosave = nosave
        self.classes = classes
        self.agnostic_nms = agnostic_nms
        self.augment = augment
        self.visualize = visualize
        self.update = update
        self.project = project
        self.name = name
        self.exist_ok = exist_ok
        self.line_thickness = line_thickness
        self.hide_labels = hide_labels
        self.hide_conf = hide_conf
        self.half = half
        self.dnn = dnn

    def run(self):
        source = str(self.source)
        save_img = not self.nosave and not source.endswith('.txt')  # save inference images
        is_file = Path(source).suffix[1:] in (IMG_FORMATS + VID_FORMATS)
        is_url = source.lower().startswith(('rtsp://', 'rtmp://', 'http://', 'https://'))
        webcam = source.isnumeric() or source.endswith('.txt') or (is_url and not is_file)
        if is_url and is_file:
            source = check_file(source)  # download

        # Directories
        save_dir = increment_path(Path(self.project) / self.name, exist_ok=self.exist_ok)  # increment run
        (save_dir / 'labels' if self.save_txt else save_dir).mkdir(parents=True, exist_ok=True)  # make dir

        # Load model
        device = select_device(self.device)
        model = DetectMultiBackend(self.weights, device=device, dnn=self.dnn, data=self.data)
        stride, names, pt, jit, onnx, engine = model.stride, model.names, model.pt, model.jit, model.onnx, model.engine
        imgsz = check_img_size(self.imgsz, s=stride)  # check image size

        # Half
        self.half &= (pt or jit or onnx or engine) and device.type != 'cpu'  # FP16 supported on limited backends with CUDA
        if pt or jit:
            model.model.half() if self.half else model.model.float()

        # Dataloader
        if webcam:
            view_img = check_imshow()
            cudnn.benchmark = True  # set True to speed up constant image size inference
            dataset = LoadStreams(source, img_size=imgsz, stride=stride, auto=pt)
            bs = len(dataset)  # batch_size
        else:
            dataset = LoadImages(source, img_size=imgsz, stride=stride, auto=pt)
            bs = 1  # batch_size
        vid_path, vid_writer = [None] * bs, [None] * bs

        # Run inference
        model.warmup(imgsz=(1, 3, *imgsz), half=self.half)  # warmup
        dt, seen = [0.0, 0.0, 0.0], 0
        for path, im, im0s, vid_cap, s in dataset:
            t1 = time_sync()
            im = torch.from_numpy(im).to(device)
            im = im.half() if self.half else im.float()  # uint8 to fp16/32
            im /= 255  # 0 - 255 to 0.0 - 1.0
            if len(im.shape) == 3:
                im = im[None]  # expand for batch dim
            t2 = time_sync()
            dt[0] += t2 - t1

            # Inference
            visualize = increment_path(save_dir / Path(path).stem, mkdir=True) if self.visualize else False
            pred = model(im, augment=self.augment, visualize=visualize)
            t3 = time_sync()
            dt[1] += t3 - t2

            # NMS
            pred = non_max_suppression(pred, self.conf_thres, self.iou_thres, self.classes, self.agnostic_nms,
                                       max_det=self.max_det)
            dt[2] += time_sync() - t3

            # Second-stage classifier (optional)
            # pred = utils.general.apply_classifier(pred, classifier_model, im, im0s)

            # Process predictions
            for i, det in enumerate(pred):  # per image
                seen += 1
                if webcam:  # batch_size >= 1
                    p, im0, frame = path[i], im0s[i].copy(), dataset.count
                    s += f'{i}: '
                else:
                    p, im0, frame = path, im0s.copy(), getattr(dataset, 'frame', 0)

                p = Path(p)  # to Path
                save_path = str(save_dir / p.name)  # im.jpg
                txt_path = str(save_dir / 'labels' / p.stem) + (
                    '' if dataset.mode == 'image' else f'_{frame}')  # im.txt
                s += '%gx%g ' % im.shape[2:]  # print string
                gn = torch.tensor(im0.shape)[[1, 0, 1, 0]]  # normalization gain whwh
                imc = im0.copy() if self.save_crop else im0  # for save_crop
                annotator = Annotator(im0, line_width=self.line_thickness, example=str(names))
                if len(det):
                    # Rescale boxes from img_size to im0 size
                    det[:, :4] = scale_coords(im.shape[2:], det[:, :4], im0.shape).round()

                    # Print results
                    for c in det[:, -1].unique():
                        n = (det[:, -1] == c).sum()  # detections per class
                        s += f"{n} {names[int(c)]}{'s' * (n > 1)}, "  # add to string

                    mylabel = []
                    # Write results
                    for *xyxy, conf, cls in reversed(det):
                        if self.save_txt:  # Write to file
                            xywh = (xyxy2xywh(torch.tensor(xyxy).view(1, 4)) / gn).view(-1).tolist()  # normalized xywh
                            line = (cls, *xywh, conf) if self.save_conf else (cls, *xywh)  # label format
                            with open(txt_path + '.txt', 'a') as f:
                                f.write(('%g ' * len(line)).rstrip() % line + '\n')

                        if save_img or self.save_crop or self.view_img:  # Add bbox to image
                            c = int(cls)  # integer class
                            label = None if self.hide_labels else (names[c] if self.hide_conf else f'{names[c]} {conf:.2f}')
                            mylabel.append(str(label))
                            annotator.box_label(xyxy, label, color=colors(c, True))
                            if self.save_crop:
                                save_one_box(xyxy, imc, file=save_dir / 'crops' / names[c] / f'{p.stem}.jpg', BGR=True)

                # Print time (inference-only)
                LOGGER.info(f'{s}Done. ({t3 - t2:.3f}s)')

                # Stream results
                im0 = annotator.result()
                if self.view_img:
                    cv2.imshow(str(p), im0)
                    cv2.waitKey(1)  # 1 millisecond

                # Save results (image with detections)
                if save_img:
                    if dataset.mode == 'image':
                        cv2.imwrite(save_path, im0)
                    else:  # 'video' or 'stream'
                        if vid_path[i] != save_path:  # new video
                            vid_path[i] = save_path
                            if isinstance(vid_writer[i], cv2.VideoWriter):
                                vid_writer[i].release()  # release previous video writer
                            if vid_cap:  # video
                                fps = vid_cap.get(cv2.CAP_PROP_FPS)
                                w = int(vid_cap.get(cv2.CAP_PROP_FRAME_WIDTH))
                                h = int(vid_cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
                            else:  # stream
                                fps, w, h = 30, im0.shape[1], im0.shape[0]
                                save_path += '.mp4'
                            vid_writer[i] = cv2.VideoWriter(save_path, cv2.VideoWriter_fourcc(*'mp4v'), fps, (w, h))
                        vid_writer[i].write(im0)

        # Print results
        t = tuple(x / seen * 1E3 for x in dt)  # speeds per image
        LOGGER.info(f'Speed: %.1fms pre-process, %.1fms inference, %.1fms NMS per image at shape {(1, 3, *imgsz)}' % t)
        if self.save_txt or save_img:
            s = f"\n{len(list(save_dir.glob('labels/*.txt')))} labels saved to {save_dir / 'labels'}" if self.save_txt \
                else ''
            LOGGER.info(f"Results saved to {colorstr('bold', save_dir)}{s}")
        if self.update:
            strip_optimizer(self.weights)  # update model (to fix SourceChangeWarning)

        return mylabel
        

The code is basically the same as the run function. The idea of run function is to load models and pictures for model prediction and reasoning. The run function in class modifies the images directory, which can be modified by yourself. The function will return the recognized object label and the corresponding confidence, which can be used for other processing.

2, Call detect class

The following is a routine to use this API. You need to put the yolov5 source folder into the program directory.

import cv2
import yolov5-master.detect
import os

video_capture = cv2.VideoCapture(0)
detect_api = yolov5-master.detect.DetectAPI(exist_ok=True)

while True:
	k = cv2.waitKey(1)
    ret, frame = video_capture.read()
    
    path = 'Your catalog/yolov5-master/data/myimages'
    cv2.imwrite(os.path.join(path, 'test.jpg'), frame)
    
    label = detect_api.run()
    print(str(label))
    
    image = cv2.imread('Your catalog/yolov5-master/runs/detect/myexp/test.jpg', flags=1)
    cv2.imshow("video", image)

    if k == 27:  # Press ESC to exit the window
        break

video_capture.release()

Parameter exist in instantiated object_ The function of OK = true is that the generated exp directory will be overwritten by itself without subsequent exp1, exp2, exp3, etc., which is convenient for real-time processing.

epilogue

This article assumes that you can successfully run detect Py and then make API interfaces. When using IP camera or video stream, you can modify the parameters in the instantiation.