使用opencv在python脚本中进行双重imshow

Question

我有以下代码：

import numpy as np
import cv2
import pickle
import rtsp
import PIL as Image

face_cascade = cv2.CascadeClassifier('cascades\data\haarcascade_frontalface_alt2.xml')
recognizer = cv2.face.LBPHFaceRecognizer_create()
recognizer.read("trainner.yml")

labels = {"person_name": 1}
with open("labels.pickle", 'rb') as f:
    og_labels = pickle.load(f)
    labels = {v:k for k,v in og_labels.items()}

url = 'rtsp://user:pass@xxx.xxx.x.xxx:YYYY/stream0/mobotix.mjpeg'
with rtsp.Client(url) as client:
  client.preview()
  while True:
    frame = client.read(raw=True)
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    faces = face_cascade.detectMultiScale(gray, scaleFactor=1.3, minNeighbors=5)
    for (x,y,w,h) in faces:
      print(x,y,w,h)
      roi_gray = gray[y:y+h, x:x+w]
      roi_color = frame[y:y+h, x:x+w]
        
      #recognize?
      id_, conf = recognizer.predict(roi_gray)
      if conf>=45: # and conf <=85:
        print(id_)
        print(labels[id_])
        font = cv2.FONT_HERSHEY_SIMPLEX
        name = labels[id_]
        color = (0,0,255)
        stroke = 2
        cv2.putText(frame, name, (x,y), font, 1, color, stroke, cv2.LINE_AA)

      #img_item = "my-image.png"
      #cv2.imwrite(img_item, roi_gray)

      color = (0, 0, 255)
      stroke = 2
      end_cord_x = x + w
      end_cord_y = y + h
      cv2.rectangle(frame, (x,y), (end_cord_x, end_cord_y), color, stroke)

    cv2.imshow('IP cam',frame)
   
    if cv2.waitKey(20) & 0xFF == ord('q'):
        break

cv2.destroyAllWindows()

一切正常，我正在运行我的代码，首先它打开“client.preview”的凸轮视图，此时人脸检测不起作用。当我关闭这个时，IPcam 窗口打开并且一切正常。 （RTSP 流仍然会丢失很多帧，但没有直接问题）。

如果我不使用代码“client.preview”，我会因为 src_empty 而从 opencv 收到错误消息。 如果我尝试将代码更改为“client.read()”，则由于 src_empty，opencv 会发生错误。

我应该如何解决这个问题？

Answer 1

在 rtsp 客户端收到第一帧之前，rtsp 客户端上的读取调用将返回 None。当您调用“client.preview”时，打开窗口所需的时间使 rtsp 客户端有足够的时间在调用第一次读取之前从流中接收第一帧。超出此范围的所有读取调用将始终返回一个框架，这就是为什么当它包含在代码中时一切正常。您的问题的解决方案是检查 rtsp 客户端的读取功能的结果，以确保您在处理之前已收到帧。

import numpy as np
import cv2
import pickle
import rtsp
import PIL as Image
import time

face_cascade = cv2.CascadeClassifier('cascades\data\haarcascade_frontalface_alt2.xml')
recognizer = cv2.face.LBPHFaceRecognizer_create()
recognizer.read("trainner.yml")

labels = {"person_name": 1}
with open("labels.pickle", 'rb') as f:
    og_labels = pickle.load(f)
    labels = {v:k for k,v in og_labels.items()}

url = 'rtsp://user:pass@xxx.xxx.x.xxx:YYYY/stream0/mobotix.mjpeg'
with rtsp.Client(url) as client:
  client.preview()
  while True:
    frame = client.read(raw=True)
    if frame is not None:
        time.sleep(.10)
    else:
        gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
        faces = face_cascade.detectMultiScale(gray, scaleFactor=1.3, minNeighbors=5)
        for (x,y,w,h) in faces:
        print(x,y,w,h)
        roi_gray = gray[y:y+h, x:x+w]
        roi_color = frame[y:y+h, x:x+w]
            
        #recognize?
        id_, conf = recognizer.predict(roi_gray)
        if conf>=45: # and conf <=85:
            print(id_)
            print(labels[id_])
            font = cv2.FONT_HERSHEY_SIMPLEX
            name = labels[id_]
            color = (0,0,255)
            stroke = 2
            cv2.putText(frame, name, (x,y), font, 1, color, stroke, cv2.LINE_AA)

        #img_item = "my-image.png"
        #cv2.imwrite(img_item, roi_gray)

        color = (0, 0, 255)
        stroke = 2
        end_cord_x = x + w
        end_cord_y = y + h
        cv2.rectangle(frame, (x,y), (end_cord_x, end_cord_y), color, stroke)

        cv2.imshow('IP cam',frame)
    
        if cv2.waitKey(20) & 0xFF == ord('q'):
            break

cv2.destroyAllWindows()

Answer 2

好的，我知道 RTSP 协议首先发送空帧并建立缓冲区。

with rtsp.Client(url) as client:
  while True:
    frame = client.read(raw=True)
    if not frame:
        time.sleep(.30)
    else:
      gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
      faces = face_cascade.detectMultiScale(gray, scaleFactor=1.3, minNeighbors=5)
      for (x,y,w,h) in faces:
        
      cv2.imshow('IP cam',frame)
      
      if cv2.waitKey(20) & 0xFF == ord('q'):
        break

cv2.destroyAllWindows()

由于双重功能，我删除了以下行：client.preview()。 代码正在启动，在一段时间后我收到以下错误：

if not frame:
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()