我正在使用 python 套接字将图像从笔记本电脑的相机(客户端)传输到我的树莓派(服务器)。事情是这样的,我连接到 socket ,然后我的客户端等待信号以拍照。发送信号(来 self 的服务器)时,我的客户拍照并按顺序发送以下数据;首先是表示图片大小的数字长度(例如,对于 10000 字节,数字为 5,对于 100000 字节,数字为 6,依此类推),然后发送实际大小,最后将照片作为字节串发送。该过程无限次重复
客户端.py
import cv2
import socket
import os
def send_msg(s, msg):
s.sendall(msg)
s = socket.socket()
port = 24999
ip = '192.168.1.3'
s.connect((ip, port))
video = cv2.VideoCapture(0)
s.recv(1) #Wait until data is sent
while True:
_, img = video.read()
img = cv2.resize(img, (0,0), fx = 0.4, fy = 0.4) #reduce image size
cv2.imwrite("test.jpg", img) #save img
size = os.path.getsize("test.jpg") #get image size
img_str = cv2.imencode('.jpg', img)[1].tostring() #convert to bytes string
sizenum = str(len(str(size))) #how many digits the image size contains
send_msg(s, sizenum.encode())
send_msg(s, str(size).encode('utf-8')) #send actual image size
send_msg(s, img_str) #finally send the image
s.recv(1) #Wait until data is sent
服务器.py
import socket
import ast
def send_msg(client, msg):
client.sendall(msg+b'\r\n')
def recvall(sock, n):
# Helper function to recv n bytes or return None if EOF is hit
data = bytearray()
while len(data) < n:
packet = sock.recv(n - len(data))
if not packet:
return None
data.extend(packet)
return data
def take_photo(cl):
#RECEIVE LENGTH OF SIZE
while True:
lensize = cl.recv(1)
lensize = lensize.decode('utf-8')
if lensize != "":
break
print("Size is a",lensize,"-digit number")
lensize = lensize.replace("\n","").replace(" ","").replace("\r","")
#RECEIVE SIZE
size_pic = recvall(cl,ast.literal_eval(lensize)).decode('utf-8')
size_pic = size_pic.replace("\n","").replace(" ","").replace("\r","")
print("Exact size is",size_pic)
#RECEIVE PHOTO
return lensize,size_pic,bytearray(recvall(cl,ast.literal_eval(size_pic)))
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind(("192.168.1.3",24999))
s.listen(1)
while True:
cl_image, addr = s.accept()
break
while True:
try:
send_msg(cl_image, b"1") #Send signal
size1, size2, photo = take_photo(cl_image)
print(photo)
except KeyboardInterrupt:
print("error")
s.close()
问题 运行服务器时,运行几秒后出现问题(有时它只运行 1 秒就抛出任何异常,有时它运行 5 秒或更长时间)
示例运行 1(服务器)
Size is a 5 -digit number
Exact size is 21263
7294 from 21263 Not all bytes were read
18974 from 21263 Not all bytes were read
Size is a 5 -digit number
Exact size is 21226
2915 from 21226 Not all bytes were read
4375 from 21226 Not all bytes were read
11675 from 21226 Not all bytes were read
18975 from 21226 Not all bytes were read
Size is a 5 -digit number
Exact size is 21412
2915 from 21412 Not all bytes were read
7295 from 21412 Not all bytes were read
14595 from 21412 Not all bytes were read
Size is a . -digit number
Traceback (most recent call last):
File "sending_test.py", line 46, in <module>
size1, size2, photo = take_photo(cl_image)
File "sending_test.py", line 27, in take_photo
size_pic = recvall(cl,ast.literal_eval(lensize)).decode('utf-8')
File "/usr/lib/python3.7/ast.py", line 46, in literal_eval
node_or_string = parse(node_or_string, mode='eval')
File "/usr/lib/python3.7/ast.py", line 35, in parse
return compile(source, filename, mode, PyCF_ONLY_AST)
File "<unknown>", line 1
.
示例运行 2(服务器)
Size is a 5 -digit number
Exact size is 20653
7294 from 20653 Not all bytes were read
14594 from 20653 Not all bytes were read
18974 from 20653 Not all bytes were read
Size is a 5 -digit number
Exact size is 20595
2915 from 20595 Not all bytes were read
8755 from 20595 Not all bytes were read
10215 from 20595 Not all bytes were read
18975 from 20595 Not all bytes were read
Traceback (most recent call last):
File "sending_test.py", line 46, in <module>
size1, size2, photo = take_photo(cl_image)
File "sending_test.py", line 21, in take_photo
lensize = lensize.decode('utf-8')
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 0: invalid start byte
我还在我的服务器循环中插入了一个 print(photo) 命令以查看发生了什么以及结果(参见最后一行与其他行的比较)
Size is a 3 -digit number
Exact size is 828
bytearray(b'\xff\xd8\xff.......\xff\xd9')
Size is a 3 -digit number
Exact size is 831
bytearray(b'\xff\xd8\xff......\xff\xd9')
Size is a 3 -digit number
Exact size is 831
bytearray(b'\xff\xd8\xff.......\xff\xd9383')
这意味着它读取了它应该拥有的多 (3) 个字节(因为 3 表示大小长度,83 来自图像大小,类似于 (83x)
最佳答案
根据评论,我做了如下几处更改:
我不是将 JPEG 写入磁盘然后计算其大小,然后再次将其编码到内存并转换为字符串并发送,而是将 JPEG 编码到内存缓冲区,获取其大小并发送它
我没有发送一个字符串来表示视频帧中的字节数,而是将字节数作为 4 字节网络顺序整数发送。让生活更轻松
它似乎在我的机器上工作得非常可靠。
这是客户端:
#!/usr/bin/env python3
import cv2
import socket
import os
import struct
ip, port = '192.168.0.8', 24999
s = socket.socket()
s.connect((ip, port))
# Start video reader
video = cv2.VideoCapture(0)
while True:
# Wait till data requested, as indicated by receipt of single byte
s.recv(1)
print('CLIENT: Image requested')
# Read a frame of video and reduce size
_, img = video.read()
img = cv2.resize(img, (0,0), fx = 0.4, fy = 0.4)
# JPEG-encode into memory buffer and get size
_, buffer = cv2.imencode('.jpg', img)
nBytes = buffer.size
print(f'CLIENT: nBytes={nBytes}')
# Send 4-byte network order frame size and image
hdr = struct.pack('!i',nBytes)
s.sendall(hdr)
s.sendall(buffer)
这是服务器:
#!/usr/bin/env python3
import time
import socket
import struct
def recvall(sock, n):
# Helper function to recv n bytes or return None if EOF is hit
data = bytearray()
while len(data) < n:
packet = sock.recv(n - len(data))
if not packet:
return None
data.extend(packet)
return data
def take_photo(cl):
# Get header with number of bytes
header = cl.recv(4)
nBytes = struct.unpack('!i',header)[0]
# Receive actual image
img = recvall(cl, nBytes)
return img
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind(("192.168.0.8",24999))
s.listen(1)
while True:
cl_image, addr = s.accept()
break
while True:
try:
# Request image by sending a single byte
cl_image.sendall(b'1')
photo = take_photo(cl_image)
time.sleep(1)
print(f'SERVER: photo received, {len(photo)} bytes')
except KeyboardInterrupt:
print("error")
s.close()
关键字:TCP 套接字、流、基于流、基于流、消息、基于消息、成帧协议(protocol)、framed、htonl、网络顺序、数据包、素数。
关于发送图像时出现 Python 套接字错误。无法解码字节/意外的 EOF,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/61048661/