Python - Extracting and Saving Video Frames

python

video-processing

opencv

frame-extraction

byAnton Shumikhin·Mar 3, 2025

For extracting and saving frames from a video in Python, OpenCV is your go-to. Install it with pip install opencv-python. The heroes of our tale are cv2.VideoCapture, which loads the video, and cv2.imwrite, which empowers you to save frames. Here's the simplified example:

import cv2

cap = cv2.VideoCapture('video.mp4')
index = 0
while True:
    ret, frame = cap.read()
    if not ret: break
    cv2.imwrite(f"frame{index}.jpg", frame)
    index += 1
cap.release()

Run this script, let OpenCV work its magic, and behold as every frame is stored as a neat JPG.

Setting the stage

Before you attempt frame extraction, it's paramount that your video file is reachable and your output directory is ready.

The right path: The video file ('video.mp4') should be in the same directory as your script or provide the absolute path.
Prepping the ground: Before saving, ensure the output directory exists. Enter, the os module.

import os

output_dir = "extracted_frames"
if not os.path.exists(output_dir):
    # It wasn't just a boulder... it was a directory! *cries in Spongebob*
    os.makedirs(output_dir)

cv2.imwrite(f"{output_dir}/frame{index}.jpg", frame)

Time for some flair

Targeting large videos or fancy features like interval extraction or performance analysis? Here's how you jazz it up:

Interval Extraction: With cv2.CAP_PROP_POS_MSEC, you can pinpoint specific moments in time like a movie director.
Track Progress: With every saved frame, print a message for that sweet sense of productive self-satisfaction.
Performance Analysis: With the time module, make haste to catch those pesky performance slowpokes.

import time

start_time = time.time()
# Imagine this: you in a coding sprint, transcending time. Yeah, that's gonna be you soon!
# ...
print(f"Frame {index} saved. Time elapsed: {time.time() - start_time} seconds. Who needs a DeLorean, right?")

Covering all bases

Design your script to be fortuitous using higher-grade error-handling and resource management techniques.

Try/Except blocks: For every exception encountered– the system that says "Oopsie Daisy!".
Resource Management: cap.release() ensures you're not hoarding memory. Remember, sharing is caring!

try:
    # File saving logic. It's not rocket science, I promise!
except IOError as e:
    print(f"I felt a great disturbance in the Code, as if millions of files suddenly cried out in terror and were suddenly silenced. I fear something terrible has happened: {e}")
finally:
    cap.release()

Command-line mastery

To shape your script into a command-line beast, bring in the argparse big guns:

import argparse

parser = argparse.ArgumentParser(description="Extract frames from a video.")
parser.add_argument('video_path', type=str, help="Path to the video file.")
parser.add_argument('output_path', type=str, help="Path to the output directory.")
args = parser.parse_args()

# Bask in the glory of args.video_path and args.output_path

Putting Humpty Dumpty back together

Extracted frames can be pieced back into a video using cv2.VideoWriter, a handy tool akin to a reverse time machine, but for video frames.

from glob import glob

frame_array = sorted(glob('extracted_frames/*.jpg'), key=lambda x: int(x.split('frame')[1].split('.jpg')[0]))

# Define the codec using the spell, cv2.VideoWriter_fourcc, and create VideoWriter object
fourcc = cv2.VideoWriter_fourcc(*'MP4V')
out = cv2.VideoWriter('output_video.mp4', fourcc, 20.0, (width, height))

for frame_path in frame_array:
    frame = cv2.imread(frame_path)
    out.write(frame)  # Elementary, my dear Watson!

out.release()