Convert surround sound to stereo for all files in a directory

convert_surround_to_stereo.py

#!/usr/bin/python3

# Convert files with surround sound to use stereo
# CAUTION: will overwrite original file!


# Some additional bash helpers

# convert all videos in directory to smaller size, output in /tmp
# for f in `ls | grep mp4`; do ffmpeg -i $f -vf scale=720:-2 -c:a copy /tmp/$f; done
# 
# convert video from surround to stereo, output in /tmp
# ffmpeg -i xyz.mkv -c:v copy -ac 2 -af "pan=stereo|FL=0.8*FC+0.40*FL+0.40*BL|FR=0.8*FC+0.40*FR+0.40*BR" /tmp/xyz.mkv


import os
import subprocess

dstRoot = "/tmp"
srcRoot = "/path/to/your/media"

def main():
    for root, dirs, filenames in os.walk(srcRoot):
        for filename in filenames:
            filelocation = os.path.join(root, filename)
            if isVideo(filelocation):
                surround = isSurround(filelocation)
                if surround:
                    convertToStereo(filelocation)

def log(s):
    f = open("converted_videos.txt", 'a')
    f.write(s + "\n")
    f.close()

def isVideo(src):
    videoExts = ["avi", "mkv", "mp4"]
    ext = src.split(".")[-1]
    return ext in videoExts

def isSurround(src):
    cmd = ["ffmpeg", "-i", src]
    p = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    lines = p.stderr.decode().split("\n")
    surround = False
    for line in lines:
        if line.find("Audio") > -1 and line.find("5.1") > -1:
            surround = True
            break
    return surround

def convertToStereo(src):
    # Convert
    filename = os.path.split(src)[-1]
    log("Converting %s to stereo" % filename)
    dst = os.path.join(dstRoot, filename)
    mix = "FL=0.8*FC+0.40*FL+0.40*BL|FR=0.8*FC+0.40*FR+0.40*BR"
    cmd = [
            "ffmpeg",
            "-i",
            src,
            "-c:v",
            "copy",
            "-ac",
            "2",
            "-af",
            "pan=stereo|%s" % mix,
            dst,
            ]
    p = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    # Replace with converted file
    cmd = ["mv", dst, src]
    p = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

main()