Jaman42's profile - activity

I am programming in Python, Pygame from what I understand uses opencv for its webcam functions. There is a query_image() available that polls the camera so you can start fetching a frame only when there is a frame to fetch, for example:

pygame.init()
pygame.camera.init()
webcam = pygame.camera.Camera("/dev/video0",(320,240))
webcam.start()
if(webcam.query_image()):
    image = webcam.get_image()

When I use the following code with opencv:

cap = cv2.VideoCapture(0)
rval, frame = cap.read()

It waits until the frame is fetched which is for me undesirable, is there a way to poll the camera before trying to fetch to see if there is a frame available?

I got the new webcamera and did get 30fps using the same code, my camera didn't handle low lighting very well but with the help of a flashlight I got there :)

I think I misunderstood you, I am using a release build of Opencv. I thought interpreted languages like Python was slower then compiled like C, it isn't? Or just to little to notice doing something like this?

Hi thank you for your answer, the code I posted is what I tried. Just as a test to see what FPS I could achieve. I tried it on my main PC to see if it was any different and it wasn't. That should mean that the webcam is the issue assuming I can get much better result with the code above. I ordered a new webcam that can deliver 30 fps to test with. Is it much quicker to do it in c or should I be able to get good results with Python as well?

Hi, I plan on building a ROV and I am working on my video feed atm. I will be using fiber optics for all communications and I am tinkering with opencv to stream a webcam feed with python. I might choose to use IP cameras but I wanted to learn more about how to capture frames from a webcam in python first. Since I didn't know what I was going to use in the end I bought a cheap-as-they-get noname USB webcam just to try and get everything working. This camera feed is going to be used for navigation, a seperate video recorder will probably be used for recording video.

Enough about that, now to my issue. I am getting only 8 FPS when I am capturing the frames but I suspect that is due to the cheap webcam. The webcam is connected to a pcduino 3 nano which is connected to a arduino for controlling thrusters and reading sensors. I never thought of how to utilize hardware in encoding and decoding images, I don't know enough about that part yet to tell if I can utilize any of the hardware.

Do you guys believe it's my web cam that is the bottleneck? Is it a better idea to use a IP camera or should I be able to get a decent FPS using a webcam connected to a pcduino 3 nano capturing frames with opencv?

Im programming in Python, this is the test I made:

import cv2, time
FPS = 0
cap = cv2.VideoCapture(0)

last = time.time()

for i in range(0,100):
    before = time.time()
    rval, frame = cap.read()
    now = time.time()
    print("cap.read() took: " + str(now - before))
    if(now - last >= 1):
        print(FPS)
        last = now
        FPS = 0
    else:
        FPS += 1
cap.release()

And the result is in the line of:

cap.read() took: 0.118262052536
cap.read() took: 0.118585824966
cap.read() took: 0.121902942657
cap.read() took: 0.116680860519
cap.read() took: 0.119271993637
cap.read() took: 0.117949008942
cap.read() took: 0.119143009186
cap.read() took: 0.122378110886
cap.read() took: 0.116139888763