整体流程：

      1.首先现在rtsp-server服务器(如果采用的是虚拟机或者是服务器，可以下载对应的linux服务器),我下载的是图片上的两个版本。下载完毕后直接打开文件夹下的mediamtx.exe

            Releases · bluenviron/mediamtx (github.com)

          

    2.在代码中执行main.py函数

rtmp_server = 'rtmp://你的主机ip:1935/video'

if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('--imgpath', type=str, default='video/test.mp4', help="image path")
    parser.add_argument('--modelpath', type=str, default='models/yolov7-tiny_384x640.onnx',
                        choices=["models/yolov7_640x640.onnx", "models/yolov7-tiny_640x640.onnx",
                                 "models/yolov7_736x1280.onnx", "models/yolov7-tiny_384x640.onnx",
                                 "models/yolov7_480x640.onnx", "models/yolov7_384x640.onnx",
                                 "models/yolov7-tiny_256x480.onnx", "models/yolov7-tiny_256x320.onnx",
                                 "models/yolov7_256x320.onnx", "models/yolov7-tiny_256x640.onnx",
                                 "models/yolov7_256x640.onnx", "models/yolov7-tiny_480x640.onnx",
                                 "models/yolov7-tiny_736x1280.onnx", "models/yolov7_256x480.onnx"],
                        help="onnx filepath")
    parser.add_argument('--confThreshold', default=0.3, type=float, help='class confidence')
    parser.add_argument('--nmsThreshold', default=0.5, type=float, help='nms iou thresh')
    args = parser.parse_args()

    # Initialize YOLOv7 object detector
    yolov7_detector = YOLOv7(args.modelpath, conf_thres=args.confThreshold, iou_thres=args.nmsThreshold)

    VID_FORMATS = ['asf', 'avi', 'gif', 'm4v', 'mkv', 'mov', 'mp4', 'mpeg', 'mpg', 'wmv']  # include video suffixes
    imgpath = args.imgpath
    print(imgpath.split('.')[-1])
    if imgpath.split('.')[-1] in VID_FORMATS:
        cap = cv2.VideoCapture(0)
        pusher = StreamPusher(rtmp_server)
        while True:
            success, srcimg = cap.read()
            srcimg = imutils.resize(srcimg, width=640)
            t1 = time.time()
            boxes, scores, class_ids = yolov7_detector.detect(srcimg)
            print(time.time() - t1)  # 测量处理一帧图像的时间 用于评估模型的处理速度或性能(推理时间)
            # Draw detections
            dstimg = yolov7_detector.draw_detections(srcimg, boxes, scores, class_ids)
            print(time.time() - t1)  # 测量了模型的推理时间以及绘制检测结果的时间
            winName = 'Deep learning object detection in OpenCV'
            # cv2.namedWindow(winName, 0)
            # cv2.imshow(winName, dstimg)

            cv2.waitKey(1)
            pusher.streamPush(dstimg)
        cv2.destroyAllWindows()
    else:
        srcimg = cv2.imread(args.imgpath)
        # Detect Objects
        t1 = time.time()
        boxes, scores, class_ids = yolov7_detector.detect(srcimg)
        print(time.time() - t1)
        # Draw detections
        dstimg = yolov7_detector.draw_detections(srcimg, boxes, scores, class_ids)
        print(time.time() - t1)
        winName = 'Deep learning object detection in OpenCV'
        cv2.namedWindow(winName, 0)
        cv2.imshow(winName, dstimg)
        cv2.waitKey(0)
        cv2.destroyAllWindows()

     3.采用vlc拉流：

    4.代码解析

         a.定义推流器：我在用的是ffmpeg进行推流，在虚拟环境中使用pip安装ffmpeg包

class StreamPusher:
    def __init__(self, rtmp_url):       #接受一个参数rtmq_url 该参数受用于指定rtmq服务器地址的字符串
        # 创建FFmpeg命令行参数
        ffmpeg_cmd = ['ffmpeg',
                      '-y',  # 覆盖已存在的文件
                      '-f', 'rawvideo',  #指定输入格式为原始视频帧数据
                      '-pixel_format', 'bgr24',    #指定输入数据的像素格式为BGR24(一种图像颜色编码格式)
                      '-video_size', '640x480',    #指定输入视频的尺寸为640*480
                      '-i', '-',  # 从标准输入读取数据
                      '-c:v', 'libx264',      #指定视频编码器为libx264(H.264编码器)
                      '-preset', 'ultrafast',   #使用ultrafast预设，以获得更快的编码速度
                      '-tune', 'zerolatency', #使用zerolatency调整 以降低延迟
                      '-pix_fmt', 'yuv420p',     #指定输出视频像素格式为yuv420p
                      '-f', 'flv',      #指定输出格式为FLV
                      rtmp_url]   #指定输出目标为‘rtmp_url' 即RTMP服务器地址
        print('ffmpeg_cmd:', ffmpeg_cmd)
        # 启动 ffmpeg
        self.ffmepg_process = subprocess.Popen(ffmpeg_cmd, stdin=subprocess.PIPE)

    def streamPush(self, frame):    #用于推送视频帧数据到FFmpeg进程
        self.ffmepg_process.stdin.write(frame.tobytes())

     b.采用onnx格式文件来封装yolo的模型权重文件(可以去github上下载yolo源码生成.onnx文件)，因为onnx只是模型和权重文件，其他一些的后处理组件要自己定义，具体如下：

class YOLOv7:
    def __init__(self, path, conf_thres=0.7, iou_thres=0.5):
        self.conf_threshold = conf_thres
        self.iou_threshold = iou_thres
        self.class_names = list(map(lambda x: x.strip(), open('coco.names', 'r').readlines()))
        # Initialize model
        self.session = onnxruntime.InferenceSession(path, providers=['CUDAExecutionProvider', 'CPUExecutionProvider'])
        model_inputs = self.session.get_inputs()
        self.input_names = [model_inputs[i].name for i in range(len(model_inputs))]
        self.input_shape = model_inputs[0].shape
        self.input_height = self.input_shape[2]
        self.input_width = self.input_shape[3]
        
        model_outputs = self.session.get_outputs()
        self.output_names = [model_outputs[i].name for i in range(len(model_outputs))]
        self.has_postprocess = 'score' in self.output_names
    
    def detect(self, image):
        input_tensor = self.prepare_input(image)
        
        # Perform inference on the image
        outputs = self.session.run(self.output_names, {self.input_names[0]: input_tensor})
        
        if self.has_postprocess:
            boxes, scores, class_ids = self.parse_processed_output(outputs)
        
        else:
            # Process output data
            boxes, scores, class_ids = self.process_output(outputs)
        
        return boxes, scores, class_ids
    
    def prepare_input(self, image):
        self.img_height, self.img_width = image.shape[:2]
        
        input_img = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
        
        # Resize input image
        input_img = cv2.resize(input_img, (self.input_width, self.input_height))
        
        # Scale input pixel values to 0 to 1
        input_img = input_img / 255.0
        input_img = input_img.transpose(2, 0, 1)
        input_tensor = input_img[np.newaxis, :, :, :].astype(np.float32)
        return input_tensor
    
    def process_output(self, output):
        predictions = np.squeeze(output[0])    #输出一个多维数组
        
        # Filter out object confidence scores below threshold
        obj_conf = predictions[:, 4]
        predictions = predictions[obj_conf > self.conf_threshold]
        obj_conf = obj_conf[obj_conf > self.conf_threshold]
        
        # Multiply class confidence with bounding box confidence
        predictions[:, 5:] *= obj_conf[:, np.newaxis]
        
        # Get the scores
        scores = np.max(predictions[:, 5:], axis=1)
        
        # Filter out the objects with a low score
        valid_scores = scores > self.conf_threshold
        predictions = predictions[valid_scores]
        scores = scores[valid_scores]
        
        # Get the class with the highest confidence
        class_ids = np.argmax(predictions[:, 5:], axis=1)
        
        # Get bounding boxes for each object
        boxes = self.extract_boxes(predictions)
        
        # Apply non-maxima suppression to suppress weak, overlapping bounding boxes
        # indices = nms(boxes, scores, self.iou_threshold)
        nms_indices = cv2.dnn.NMSBoxes(boxes.tolist(), scores.tolist(), self.conf_threshold, self.iou_threshold)
        indices = np.array(nms_indices).flatten().astype(int)
        return boxes[indices], scores[indices], class_ids[indices]
    
    def parse_processed_output(self, outputs):
        
        scores = np.squeeze(outputs[self.output_names.index('score')])
        predictions = outputs[self.output_names.index('batchno_classid_x1y1x2y2')]
        
        # Filter out object scores below threshold
        valid_scores = scores > self.conf_threshold
        predictions = predictions[valid_scores, :]
        scores = scores[valid_scores]
        
        # Extract the boxes and class ids
        # TODO: Separate based on batch number
        batch_number = predictions[:, 0]
        class_ids = predictions[:, 1]
        boxes = predictions[:, 2:]
        
        # In postprocess, the x,y are the y,x
        boxes = boxes[:, [1, 0, 3, 2]]
        
        # Rescale boxes to original image dimensions
        boxes = self.rescale_boxes(boxes)
        
        return boxes, scores, class_ids
    
    def extract_boxes(self, predictions):
        # Extract boxes from predictions
        boxes = predictions[:, :4]
        
        # Scale boxes to original image dimensions
        boxes = self.rescale_boxes(boxes)
        
        # Convert boxes to xywh format
        boxes_ = np.copy(boxes)
        boxes_[..., 0] = boxes[..., 0] - boxes[..., 2] * 0.5
        boxes_[..., 1] = boxes[..., 1] - boxes[..., 3] * 0.5 
        return boxes_
    
    def rescale_boxes(self, boxes):
        
        # Rescale boxes to original image dimensions
        input_shape = np.array([self.input_width, self.input_height, self.input_width, self.input_height])
        boxes = np.divide(boxes, input_shape, dtype=np.float32)
        boxes *= np.array([self.img_width, self.img_height, self.img_width, self.img_height])
        return boxes
    
    def draw_detections(self, image, boxes, scores, class_ids):
        for box, score, class_id in zip(boxes, scores, class_ids):
            x, y, w, h = box.astype(int)

            # Draw rectangle
            cv2.rectangle(image, (x, y), (x+w, y+h), (0, 0, 255), thickness=2)
            label = self.class_names[class_id]
            label = f'{label} {int(score * 100)}%'
            labelSize, baseLine = cv2.getTextSize(label, cv2.FONT_HERSHEY_SIMPLEX, 0.5, 1)
            # top = max(y1, labelSize[1])
            # cv.rectangle(frame, (left, top - round(1.5 * labelSize[1])), (left + round(1.5 * labelSize[0]), top + baseLine), (255,255,255), cv.FILLED)
            cv2.putText(image, label, (x, y - 10), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 255, 0), thickness=2)
        return image

3.采用cap = cv2.VideoCapture(0)读取本地摄像头，针对每帧进行目标检测算法然后进行推流：

    if imgpath.split('.')[-1] in VID_FORMATS:
        cap = cv2.VideoCapture("rtmp://:1935/stream")
        pusher = StreamPusher(rtmp_server)
        while True:
            success, srcimg = cap.read()
            srcimg = imutils.resize(srcimg, width=640)
            t1 = time.time()
            boxes, scores, class_ids = yolov7_detector.detect(srcimg)
            print(time.time() - t1)  #测量处理一帧图像的时间 用于评估模型的处理速度或新能(推理时间)
            # Draw detections
            dstimg = yolov7_detector.draw_detections(srcimg, boxes, scores, class_ids)
            print(time.time() - t1)   #测量了模型的推理时间以及绘制检测结果的时间
            winName = 'Deep learning object detection in OpenCV'
            #cv2.namedWindow(winName, 0)
            #cv2.imshow(winName, dstimg)

            cv2.waitKey(1)
            pusher.streamPush(dstimg)
        cv2.destroyAllWindows()
    else:
        srcimg = cv2.imread(args.imgpath)
        # Detect Objects
        t1 = time.time()
        boxes, scores, class_ids = yolov7_detector.detect(srcimg)
        print(time.time() - t1)
        # Draw detections
        dstimg = yolov7_detector.draw_detections(srcimg, boxes, scores, class_ids)
        print(time.time() - t1)
        winName = 'Deep learning object detection in OpenCV'
        cv2.namedWindow(winName, 0)
        cv2.imshow(winName, dstimg)
        cv2.waitKey(0)
        cv2.destroyAllWindows()

效果展示：

以上代码借鉴了很多博主的文章，具体的忘记了。如有冒犯，多多谅解！

代码地址：

   GitHub - 23jisuper/yolov7-ffmpeg: 基于yolov5目标检测，使用ffmpeg推流 vlc拉流(效果还行的话点个星星⭐。😊)

后续工作：

      目标检测模型采用的是cpu进行推理的，可以采用GPU加速推理。整个代码是根据python实现的，考虑采用C++代替来提高速度。