相机流 - OpenCV 错误：（-215：断言失败）size.width>0 && size.height>0 in function 'cv::imshow'

Question

我正在尝试 stream 我的相机图像 ( Model ) 从带有 Raspberry OS 的 Raspberry Pi 3 B+ 到我的 Windows 10 PC。 它有效，但是当我在相机前拿着白色的东西并且图像很小，但不足以发送一个 package 时，我收到 OpenCV 错误：(-215:Assertion failed) size.width>0 && size.height>0 in function 'cv::imshow'

这是 python 代码和控制台 output：

发件人

import socket
import struct
import math
import cv2
import time
 
def main():
    
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    port = 60339
    fs = FrameSegment(s, port, "192.168.1.29")
    
    cap = cv2.VideoCapture(0)
    print("Startet video capture")
    while (cap.isOpened()):
        _, frame = cap.read()
        fs.udp_frame(frame)
    
    cap.release()
    cv2.destroyAllWindows()
    s.close()
  
class FrameSegment(object):
    MAX_DGRAM = 2**16
    MAX_IMAGE_DGRAM = MAX_DGRAM - 64
    
    def __init__(self, sock, port, addr):
        self.s = sock
        self.port = port
        self.addr = addr
        
    def udp_frame(self, img):
    
        compress_img = cv2.imencode('.jpg', img)[1]
        dat = compress_img.tostring()
        size = len(dat)
        num_of_segments = math.ceil(size/(self.MAX_IMAGE_DGRAM))
        array_pos_start = 0
        
        while num_of_segments:
            array_pos_end = min(size, array_pos_start + self.MAX_IMAGE_DGRAM)
            self.s.sendto(
                        struct.pack("B", num_of_segments) +
                        dat[array_pos_start:array_pos_end], 
                        (self.addr, self.port)
                        )
            array_pos_start = array_pos_end
            num_of_segments -= 1
            
main()

接收者

import numpy as np
import struct
import socket
import cv2
 
MAX_DGRAM = 2**16
index2 = False
 
def dump_buffer(s):
    """ Emptying buffer frame """
    while True:
        print("Emptying Buffer")
        seg, addr = s.recvfrom(MAX_DGRAM)
        if struct.unpack("B", seg[0:1])[0] == 1:
            print("finish emptying buffer")
            break
 
def imageReceiver():
    
    print("Socket setup")
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    s.bind(('192.168.1.29', 60339))
    dat = b''
    dump_buffer(s)
    
    while True:
        seg, addr = s.recvfrom(MAX_DGRAM)
        index = struct.unpack("B", seg[0:1])[0]
        if index > 1:
            dat += seg[1:]
        else:
            dat += seg[1:]
            img = cv2.imdecode(np.frombuffer(dat, dtype=np.uint8), 1)
            cv2.imshow('frame', img)
            if cv2.waitKey(1) & 0xFF == ord('q'):
                break
            dat = b''
    
    cv2.destroyAllWindows()
    s.close()
    
    
imageReceiver()

接收控制台 Output

Socket setup
Emptying Buffer
Emptying Buffer
finish emptying buffer
Traceback (most recent call last):
  File ".\RemoteControl.py", line 43, in <module>
    imageReceiver()
  File ".\RemoteControl.py", line 34, in imageReceiver
    cv2.imshow('frame', img)
cv2.error: OpenCV(4.5.1) C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-kh7iq4w7\opencv\modules\highgui\src\window.cpp:376: error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'cv::imshow'

Answer 1

可能是 imshow 由于某种原因收到一个空图像。 你能在调用 imshow 之前记录 img 的形状和类型吗？

我已经运行了您的发件人和接收脚本并且运行良好。 在我的镜头前快速移动不要出你的错误。

    
    while True:
        seg, addr = s.recvfrom(MAX_DGRAM)
        index = struct.unpack("B", seg[0:1])[0]
    
        if index > 1:
            dat += seg[1:]
        else:
            dat += seg[1:]
            img = cv2.imdecode(np.frombuffer(dat, dtype=np.uint8), 1)

            #--- Prevent crash if img is None 
            if img is not None:
                cv2.imshow('frame', img)
            #-----------------------------------
    
            if cv2.waitKey(1) & 0xFF == ord('q'):
                break
            dat = b''