OpenCV put text on raw files

Question

I need help to put a timestamp on images taken by an IP camera, I made a version of the code that save the image as a local file, then opencv write on it, now i'd like to write on it without saving it before, but i'm stucked. This is the code:

import requests
import time
import shutil
import os
from requests.auth import HTTPBasicAuth
import cv2
from datetime import datetime
from datetime import date
import numpy as np


url = 'http://192.168.0.138/image.jpg?cidx=366981845'


user = '****'
psw = '****'

path = 'ipCameraScreen.png'



font = cv2.FONT_HERSHEY_SIMPLEX
position = (20, 30)
color = (255, 255, 255)
font_size = 0.5
font_stroke = 1


while True:

    response = requests.get(url, auth=HTTPBasicAuth(user, psw), stream = True)
    resp_raw = response.raw

    if response.status_code == 200:

        # DEFINE TIMESTAMP
        current_date = str(date.today())
        current_time = datetime.now().strftime("%H:%M:%S")
        timestamp = (current_date + " | " + current_time)

        with open(path, 'wb') as out_file:
            shutil.copyfileobj(response.raw, out_file)
            img = np.asarray(bytearray(resp_raw.read()), dtype="uint8")
            img = cv2.imdecode(img, cv2.IMREAD_COLOR)
            cv2.putText(img, timestamp, position, font, font_size, color, font_stroke)
            cv2.imwrite(path, img)
        print("Screen saved, path:", path)
        time.sleep(3)
    else:
        print("Connection failed")


    time.sleep(3)

    if os.path.exists(path):
            os.remove(path)
            print("image removed")
            time.sleep(2)

The output is:

cv2.error: OpenCV(4.5.2) C:\Users\runneradmin\AppData\Local\Temp\pip-req-build-m8us58q4\opencv\modules\imgcodecs\src\loadsave.cpp:736: error: (-215:Assertion failed) !buf.empty() in function 'cv::imdecode_'

Plz help me and sorry for easy english

score 0 · Answer 1 · answered May 24 '21 at 09:49

0

Your error states that when you are trying to decode the array into img using imdecode(), the buffer is empty.

This means that in the previous line:

img = np.asarray(bytearray(resp_raw.read()), dtype="uint8")

The resp_raw.read() gives you an empty array.

I would analyze the GET-request that you perform with a tool like Postman, or just try to print the contents of resp_raw because it seems like it does not return you an image.

answered May 24 '21 at 09:49

Slayahh

373
4
14

I tried to print resp_raw and this is the output: – Lorenzo_inirapmoC May 24 '21 at 13:16
Try printing the response status by using print(response.status). If it is between 200-299 it is a positive response, otherwise there might be an error with the request. I would recommend using "insomnia" or "postman" applications to debug responses. – Slayahh May 24 '21 at 16:55

score -1 · Accepted Answer · answered May 24 '21 at 13:27

-1

I solved, i just re-did the request to define resp_raw, i did this:

response = requests.get(url, auth=HTTPBasicAuth(user, psw), stream = True)
resp_raw = requests.get(url, auth=HTTPBasicAuth(user, psw), stream = True).raw

instead of this:

response = requests.get(url, auth=HTTPBasicAuth(user, psw), stream = True)
resp_raw = response.raw

answered May 24 '21 at 13:27

Lorenzo_inirapmoC

33
1
9

that causes the request to be issued TWICE, hence wasting resources. the previous variant (second snippet) should be perfectly fine. however, responses might only be readable once, so pay attention to that. – Christoph Rackwitz May 25 '21 at 10:07

OpenCV put text on raw files

2 Answers2