PYNQ: PYTHON PRODUCTIVITY

Webcam video to hdmi output

I use my Logitec usb-webcam and the PYNQ-Z2 board. I want to create a video stream of the camera via hdmi out.

The code I am using is:

Capture_webcam_camera

from pynq.overlays.base import BaseOverlay
from pynq.lib.video import *
base = BaseOverlay(“base.bit”)

monitor configuration: 640*480 @ 60Hz

Mode = VideoMode(640,480,24)
hdmi_out = base.video.hdmi_out
hdmi_out.configure(Mode,PIXEL_BGR)
hdmi_out.start()

monitor (output) frame buffer size

frame_out_w = 1920
frame_out_h = 1080

camera (input) configuration

frame_in_w = 640
frame_in_h = 480

initialize camera from OpenCV

import cv2

cap = cv2.VideoCapture(0)

cap.set(cv2.CAP_PROP_FRAME_WIDTH, frame_in_w);
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, frame_in_h);

print("Capture device is open: " + str(cap.isOpened()))

Capture webcam video

while (True):
ret, frame = cap.read()

outframe = hdmi_out.newframe()
outframe[:] = frame
hdmi_out.writeframe(outframe)

cap.release()
cv2.destroyAllWindows()

The Problem is that the live video is starting, but it freezes in a couple of seconds and I get an Error

TypeError

TypeError Traceback (most recent call last)
in ()
5
6 outframe = hdmi_out.newframe()
----> 7 outframe[:] = frame
8 hdmi_out.writeframe(outframe)

TypeError: int() argument must be a string, a bytes-like object or a number, not ‘NoneType’

Does anyone know why exactly this occurs?
Thanks :slight_smile:

Usually this is a result of either the webcam or the kernel driver for it crashing. Is there anything on dmesg that indicates what might have happened?

Peter

As peter said it generally happens when camera is unable to transfer the image. You could just use a if block before display the image, it will keep running the window even if there is a frame skip:

ret, frame = cap.read()
if ret:
   outframe = hdmi_out.newframe()
   outframe[:] = frame
   hdmi_out.writeframe(outframe)
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