kivy , opencv , socket
AR
i created a code for transfer video from raspiberry pi to laptop.
can transmit the code and receive it. but can’t show in my kivy app …i would like to know is there any mistake in my client code …(not kivy opencv)
Server code for transmitting video
import socket, cv2, pickle,struct
# Socket Create
server_socket = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
host_name = socket.gethostname()
host_ip = socket.gethostbyname(host_name)
print('HOST IP:',host_ip)
port = 9998
socket_address = (host_ip,port)
# Socket Bind
server_socket.bind(socket_address)
# Socket Listen
server_socket.listen(5)
print("LISTENING AT:",socket_address)
# Socket Accept
while True:
client_socket,addr = server_socket.accept()
print('GOT CONNECTION FROM:',addr)
if client_socket:
vid = cv2.VideoCapture(0)
while(vid.isOpened()):
img,frame = vid.read()
a = pickle.dumps(frame)
message = struct.pack("Q",len(a))+a
client_socket.sendall(message)
cv2.imshow('TRANSMITTING VIDEO',frame)
key = cv2.waitKey(1) & 0xFF
if key ==ord('q'):
client_socket.close()
Client code
import socket,cv2, pickle,struct
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.image import Image
from kivy.clock import Clock
from kivy.graphics.texture import Texture
import cv2
client_socket = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
host_ip = '127.0.1.1' # paste your server ip address here
port = 9998
client_socket.connect((host_ip,port)) # a tuple
data = b""
payload_size = struct.calcsize("Q")
class CamApp(App):
def build(self):
self.img1=Image()
layout = BoxLayout()
layout.add_widget(self.img1)
#opencv2 stuffs
#self.capture = cv2.VideoCapture(0)
cv2.namedWindow("CV2 Image")
Clock.schedule_interval(self.update, 1.0/33.0)
return layout
def update(self, *args):
data = b""
while True:
if len(data) < payload_size:
packet = client_socket.recv(4*1024) # 4K
if not packet: break
data+=packet
packed_msg_size = data[:payload_size]
data = data[payload_size:]
msg_size = struct.unpack("Q",packed_msg_size)[0]
while len(data) < msg_size:
data += client_socket.recv(4*1024)
#print(data,"value: msg:", msg_szie)
frame_data = data[:msg_size]
data = data[msg_size:]
frame = pickle.loads(frame_data)
cv2.imshow("recived video", frame)
cv2.waitKey(1)
buf1 = cv2.flip(frame, 0)
buf = buf1.tostring()
texture1 = Texture.create(size=(frame.shape[1], frame.shape[0]), colorfmt='bgr')
texture1.blit_buffer(buf, colorfmt='bgr', bufferfmt='ubyte')
self.img1.texture = texture1
#cv2.imshow("RECEIVING VIDEO",frame)
#cv2.waitKey(1)
#key = cv2.waitKey(1) & 0xFF
#if key == ord('q'):
# break
client_socket.close()
#update()
CamApp().run()
The opencv code that work fine with kivy
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.image import Image
from kivy.clock import Clock
from kivy.graphics.texture import Texture
import cv2
class CamApp(App):
def build(self):
self.img1=Image()
layout = BoxLayout()
layout.add_widget(self.img1)
#opencv2 stuffs
self.capture = cv2.VideoCapture(0)
cv2.namedWindow("CV2 Image")
Clock.schedule_interval(self.update, 1.0/33.0)
return layout
def update(self, dt):
# display image from cam in opencv window
ret, frame = self.capture.read()
cv2.imshow("CV2 Image", frame)
# convert it to texture
buf1 = cv2.flip(frame, 0)
buf = buf1.tostring()
texture1 = Texture.create(size=(frame.shape[1], frame.shape[0]), colorfmt='bgr')
#if working on RASPBERRY PI, use colorfmt='rgba' here instead, but stick with "bgr" in blit_buffer.
texture1.blit_buffer(buf, colorfmt='bgr', bufferfmt='ubyte')
# display image from the texture
self.img1.texture = texture1
if __name__ == '__main__':
CamApp().run()
cv2.destroyAllWindows()
Elliot Garbus
The sockets library is blocking by default. This means if you call recv, and there is no data in the buffer, the code will wait for data. This is not compatible with kivy behavior. You can set sockets to operate in non-blocking mode.
Here is a description: https://pymotw.com/3/socket/nonblocking.html
And https://docs.python.org/3/library/socket.html#notes-on-socket-timeouts
Kivy operates an event loop. All code must return to the event loop. The kivy event loop is described here: https://kivy.org/doc/stable/guide/events.html
You need to setup the sockets in the client sockets to run in non-blocking mode. It also looks like you are calling socket.close() at the end of update. This does not look correct. I would think you would want to close the stock in the on_stop() method of app, when the program is closing.
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