FFMPEG: Detect and save the frame with the minimum blur value within a time range

detect_and_save_min_blur_frame.py

import os
import re
import subprocess

def get_blur_values(video_path, start_time, duration):
    command = [
        "ffmpeg",
        "-i", video_path,
        "-vf", f"blurdetect=block_width=32:block_height=32,metadata=print:file=-",
        "-ss", str(start_time),
        "-t", str(duration),
        "-f", "null", "-"
    ]
    
    result = subprocess.run(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
    return result.stdout

def parse_blur_values(blur_data):
    blur_values = []
    pattern = re.compile(r'frame:\d+\s+pts:\d+\s+pts_time:(\d+\.\d+)\n.*?lavfi.blur=(\d+\.\d+)')
    matches = pattern.findall(blur_data)
    
    for match in matches:
        time_in_seconds = float(match[0])
        blur_value = float(match[1])
        blur_values.append((time_in_seconds, blur_value))
        
    return blur_values

def find_minimum_blur_frame(blur_values):
    return min(blur_values, key=lambda x: x[1])

def save_frame_as_png(video_path, time, output_path):
    command = [
        "ffmpeg",
        "-i", video_path,
        "-vf", f"select='eq(n\\,{int(time * 30)})'",
        "-vsync", "vfr",
        output_path
    ]
    subprocess.run(command)

def main(video_path, start_time, duration, output_path):
    blur_data = get_blur_values(video_path, start_time, duration)
    blur_values = parse_blur_values(blur_data)
    if blur_values:
        min_blur_time, min_blur_value = find_minimum_blur_frame(blur_values)
        save_frame_as_png(video_path, min_blur_time, output_path)
        print(f"Saved frame with lowest blur value at time {min_blur_time}s to {output_path}")
    else:
        print("No blur values found in the specified time range.")

if __name__ == "__main__":
    video_path = "test.mp4"
    start_time = 0  # Start time in seconds
    duration = 3  # Duration in seconds
    output_path = "nonblurred/output.png"
    
    if not os.path.exists("nonblurred"):
        os.makedirs("nonblurred")
    
    main(video_path, start_time, duration, output_path)