Hey there, let's break down why your code is failing and get it working properly. The error points to line 5 (the FourCC setup), but there are a few other potential pitfalls in the code we should address too:

Key Issues & Fixes #

1. Invalid FourCC Code #

The 'VID' code you're using isn't a valid codec recognized by OpenCV. Different operating systems support different codecs, so use one that's compatible:

• For Windows: Use 'XVID' or 'DIVX'
• For Linux/macOS: 'MJPG' is a reliable cross-platform option

Update the FourCC line to:

fourcc = cv2.VideoWriter_fourcc(*'XVID')

2. Incorrect Camera Index #

You're using cv2.VideoCapture(1), but most systems default to the first webcam at index 0. If you only have one camera, this will fail to open the stream entirely. Switch to index 0 first, or test indices to find your active camera:

cap = cv2.VideoCapture(0)

3. Mismatched Frame Dimensions #

You've hardcoded the output resolution to (640, 480), but your webcam might capture frames at a different size. If the dimensions don't match, the VideoWriter will fail to save the video. Instead, grab the actual resolution from the camera:

# Get actual camera frame size
width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
# Initialize VideoWriter with correct dimensions
out = cv2.VideoWriter('output.avi', fourcc, 20.0, (width, height))

4. Missing Error Checks #

Your code doesn't verify if the camera opened successfully or if frames are being read properly. Add these checks to avoid cryptic errors:

• Check if the camera opened:

  if not cap.isOpened():
      print("Couldn't open the camera!")
      exit()
  

• Check if each frame was read correctly in the loop:

  ret, frame = cap.read()
  if not ret:
      print("Stream ended or failed to read frame. Exiting...")
      break
  

Full Corrected Code #

import numpy as np
import cv2

# Initialize camera (use 0 for default webcam)
cap = cv2.VideoCapture(0)

# Check if camera opened successfully
if not cap.isOpened():
    print("Couldn't open the camera!")
    exit()

# Use valid FourCC codec (XVID works on most systems)
fourcc = cv2.VideoWriter_fourcc(*'XVID')

# Get actual camera frame dimensions
width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

# Initialize VideoWriter with correct parameters
out = cv2.VideoWriter('output.avi', fourcc, 20.0, (width, height))

while(True):
    ret, frame = cap.read()
    # Check if frame was read successfully
    if not ret:
        print("Stream ended or failed to read frame. Exiting...")
        break
    
    # Convert frame to grayscale for display
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    # Save the original color frame to video
    out.write(frame)
    # Display grayscale frame
    cv2.imshow('frame', gray)
    
    # Exit on 'q' key press
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# Release all resources properly
cap.release()
out.release()
cv2.destroyAllWindows()

This should fix the video saving error and make your code more robust against common webcam issues.

内容的提问来源于stack exchange，提问作者Aniket Bote