[EV3 x Python] Stream the camera image to your PC using mjpg-streamer.

Overview

I will introduce the procedure to stream the camera image from ev3 using mjpg-streamer. With ev3dev, you can set up a streaming server just by installing the software. Create a code to display the video using OpenCV on the PC side.

Premise

• PC : mac (macOS Mojave 10.14.6)
• EV3 (ev3dev)
• vscode
• opencv-python installed

Install MJPG-streamer

I use apt-get to install MJPG-streamer, but please create a swap area in advance because it may fail due to insufficient memory with the default settings. Please refer to this article to create the method! [EV3 x Python] How to create a swap area

If you don't know how to open the terminal in the first place ↓ [EV3 x Python] SSH connection

Enter from the following command in the terminal. When asked for the password, maker

$ cd ~
$ sudo apt-get install -y cmake libv4l-dev libjpeg-dev imagemagick
$ git clone https://github.com/jacksonliam/mjpg-streamer.git
$ cd mjpg-streamer/mjpg-streamer-experimental
$ make
$ sudo make install 

Run MJPG-streamer

$ cd ~/mjpg-streamer/mjpg-streamer-experimental/
$ ./mjpg_streamer -o "output_http.so -w ./www" -i "input_uvc.so"

Images are displayed when accessing ev3 with a PC browser

If you access http://ev3dev.local:8080 with the browser of the PC to which EV3 is connected, the streaming page will open. I'm sorry in a dirty room w

Create a script to project images in Python

streaming.py

from cv2.cv2 import VideoCapture,waitKey,imshow,destroyAllWindows

#Specify the link to which the video will be sent.
cap = VideoCapture("http://ev3dev.local:8080/?action=stream")

#If the link cannot be opened
if not cap.isOpened():
    print("Cannot open a video capture.")
    exit(-1)


while True:
    #Loop ends when esc key is pressed
    k = waitKey(1)

    if k == 27:
        break

    #Get the frame of the incoming video
    ret, frame = cap.read()
    
    #If the frame could not be obtained
    if not ret:
        continue

    #Show frame
    imshow("EV3 Streaming", frame)

#Opening the capture&close the window
cap.release()
destroyAllWindows()

Execution result