Darknet: Using the python wrapper to detect video

Created on 29 Apr 2018 · 7Comments · Source: AlexeyAB/darknet

Hey, is it possible to use the python wrapper to use the demo function?
from what I've seen, its only for images right now?
thanks!

want enhancement

Source

tommmn

Most helpful comment

Not the most ideal way to do it but the simplest might be to open a video file through OpenCV and for each frame, convert the numpy array into a Darknet image by doing something like this

def array_to_image(arr):
    import numpy as np
    # need to return old values to avoid python freeing memory
    arr = arr.transpose(2,0,1)
    c = arr.shape[0]
    h = arr.shape[1]
    w = arr.shape[2]
    arr = np.ascontiguousarray(arr.flat, dtype=np.float32) / 255.0
    data = arr.ctypes.data_as(POINTER(c_float))
    im = IMAGE(w,h,c,data)
    return im, arr

saihv on 30 Apr 2018

👍3

All 7 comments

Not the most ideal way to do it but the simplest might be to open a video file through OpenCV and for each frame, convert the numpy array into a Darknet image by doing something like this

def array_to_image(arr):
    import numpy as np
    # need to return old values to avoid python freeing memory
    arr = arr.transpose(2,0,1)
    c = arr.shape[0]
    h = arr.shape[1]
    w = arr.shape[2]
    arr = np.ascontiguousarray(arr.flat, dtype=np.float32) / 255.0
    data = arr.ctypes.data_as(POINTER(c_float))
    im = IMAGE(w,h,c,data)
    return im, arr

saihv on 30 Apr 2018

👍3

@saihv hey, so I've tried your suggestion, but i get this error:
im = load_image(image, 0, 0)
ctypes.ArgumentError: argument 1: : wrong type

When I captured the frame i convert it with your function and send the image[0] to detect()
so, load_image basically get the IMAGE from your function.
any ideas? thanks!

EDIT--
I think I got it, your function replace the load_image right?
so it go through, but my application crash in the part of:
res.append((meta.names[i], dets[j].prob[i], (b.x, b.y, b.w, b.h)))

tommmn on 1 May 2018

Okay so the problem is meta.names[i], when i take it out, everything works.
@AlexeyAB any idea?

tommmn on 1 May 2018

@tommmn Can you run successfully the default file python darknet.py without any your changes?

I can run it