Sketch ass script to convert the m4s files being saved by the new Steam Game Recording feature into an mp4 file. It also allows "clipping" the last 30 seconds of the most recent active background recording.

convert_valve_video.py

import os
import subprocess
from random import sample
from uuid import uuid4
from pathlib import Path

def create_filelist(folder, init_file, file_pattern):
    files = sorted([f for f in os.listdir(folder) if f.startswith(file_pattern) and f.endswith('.m4s')])
    return [f"{os.path.join(folder, init_file)}"] + [f"{os.path.join(folder, file)}" for file in files]

def concatenate_files_with_cat(files, output_file):
    with open(output_file, 'wb') as out_file:
        for file in files:
            with open(file, 'rb') as in_file:
                out_file.write(in_file.read())

def merge_audio_video(video_file, audio_file, output_file):
    command = [
        'ffmpeg', '-y', '-i', video_file, '-i', audio_file, 
        '-c', 'copy', 
        '-analyzeduration', '100M', '-probesize', '50M', 
        output_file
    ]
    subprocess.run(command, check=True)

def decode_video(folder, output_filepath, num_last_files_to_save=0):
    uid = uuid4()
    video_combined = f'/tmp/{uid}_video_combined.mp4'
    audio_combined = f'/tmp/{uid}_audio_combined.mp4'
    final_output = output_filepath

    # Assuming init and chunk files have a consistent naming convention
    video_init = 'init-stream0.m4s'
    video_pattern = 'chunk-stream0'

    # Create file lists
    video_filelist = create_filelist(folder, video_init, video_pattern)
    if num_last_files_to_save:
        video_filelist = [video_filelist[0]] + video_filelist[1:][-num_last_files_to_save:]
    audio_filelist = [f.replace("stream0", "stream1") for f in video_filelist]

    # Concatenate files using cat
    concatenate_files_with_cat(video_filelist, video_combined)
    concatenate_files_with_cat(audio_filelist, audio_combined)

    # Merge audio and video using ffmpeg
    merge_audio_video(video_combined, audio_combined, final_output)

    # Clean up
    os.remove(video_combined)
    os.remove(audio_combined)

def get_most_recent_bg_recording_folder():
    path = sorted((Path.home() / ".local/share/Steam/userdata").glob("**/bg_*/"), key=os.path.getmtime, reverse=True)
    if not path:
        return None
    return path[0]

if __name__ == "__main__":
    # Example usage
    folder = get_most_recent_bg_recording_folder()
    decode_video(folder, "/tmp/output.mp4", num_last_files_to_save=10)