How to decode a two dimensional array string

I’m making a http request which returns a two dimensional array (string); and i tried to do HttpService:JSONDecode() but it says Can't Parse JSON, am i doing it wrong? or is there a way to decode a two dimensional array string into a table?

A code snippet would be helpful if you have one

For context, this is the raw string (i don’t know if the dots matter)

[[[0 0 0]
  [0 0 0]
  [0 0 0]
  ...
  [0 0 0]
  [0 0 0]
  [0 0 0]]

 [[0 0 0]
  [0 0 0]
  [0 0 0]
  ...
  [0 0 0]
  [0 0 0]
  [0 0 0]]

 [[0 0 0]
  [0 0 0]
  [0 0 0]
  ...
  [0 0 0]
  [0 0 0]
  [0 0 0]]

 ...

 [[0 0 0]
  [0 0 0]
  [0 0 0]
  ...
  [0 0 0]
  [0 0 0]
  [0 0 0]]

 [[0 0 0]
  [0 0 0]
  [0 0 0]
  ...
  [0 0 0]
  [0 0 0]
  [0 0 0]]

 [[0 0 0]
  [0 0 0]
  [0 0 0]
  ...
  [0 0 0]
  [0 0 0]
  [0 0 0]]]

This is the python file which handles the request

from flask import Flask, render_template
import cv2

app = Flask(__name__, template_folder='template')
PORT = 1111

video = cv2.VideoCapture('api/BadApple.mp4')

@app.route('/')
def index():
    return render_template('index.html')

@app.route('/frame/<index>', methods=['GET'])
def frame(index):
    video.set(cv2.CAP_PROP_POS_FRAMES, int(index))
    ret, frame = video.read()

    return str(frame) # here lies the problem (its a numpy.ndarray class)

app.run(host='0.0.0.0', port=PORT, debug=False)

I fixed it just by calling frame.tolist()