Converts a frame-based subtitle file to SRT format.

convert_srt.py

"""
    python convert_srt.py from.srt to.srt
    
    default frame rate for most movies is: 23.976
    encoding is set to: windows-1250 (usually non-english subtitles have frame based subtitling)
    
    Example "from.srt":
    {0}{100}Hello, world!
    {101}{300}This is a frame-based subtitle file.

    Example "to.srt":
    1
    00:00:00,000 --> 00:00:04,167
    Hello, world!

    2
    00:00:04,167 --> 00:00:10,000
    This is a frame-based subtitle file.
"""

import re
import sys

def convert_to_srt(input_file, output_file, frame_rate=23.976, encoding='utf-8'):
    try:
        with open(input_file, 'r', encoding=encoding) as infile, open(output_file, 'w', encoding='utf-8') as outfile:
            subtitle_number = 1
            for line in infile:
                match = re.match(r'\{(\d+)\}\{(\d+)\}(.*)', line)
                if match:
                    start_frame, end_frame, text = match.groups()
                    start_time = float(start_frame) / frame_rate
                    end_time = float(end_frame) / frame_rate

                    start_time_formatted = format_time(start_time)
                    end_time_formatted = format_time(end_time)

                    outfile.write(str(subtitle_number) + '\n')
                    outfile.write(f"{start_time_formatted} --> {end_time_formatted}\n")
                    outfile.write(text.strip() + '\n\n')
                    subtitle_number += 1
                elif line.strip():
                    outfile.write(line)
    except FileNotFoundError:
        print(f"Error: Input file '{input_file}' not found.")
    except UnicodeDecodeError as e:
        print(f"Encoding error: {e}. Try a different encoding (e.g., 'latin-1', 'cp1252').")
        return 
    except Exception as e:
        print(f"An error occurred: {e}")

def format_time(seconds):
    milliseconds = int(round((seconds * 1000) % 1000))
    seconds = int(seconds)
    minutes = seconds // 60
    seconds %= 60
    hours = minutes // 60
    minutes %= 60
    return f"{hours:02}:{minutes:02}:{seconds:02},{milliseconds:03}"

if __name__ == "__main__":
    if len(sys.argv) < 3:
        print("Usage: python convert_subtitles.py <input_file> <output_file> [<frame_rate>]")
        sys.exit(1)

    input_file = sys.argv[1]
    output_file = sys.argv[2]

    if len(sys.argv) > 3:
        try:
            frame_rate = float(sys.argv[3])
        except ValueError:
            print("Error: Invalid frame rate. Using default 23.976.")
            frame_rate = 23.976
    else:
        frame_rate = 23.976

    try:
        convert_to_srt(input_file, output_file, frame_rate, encoding='windows-1250')
    except Exception as e:
        print(f"An error occurred: {e}")