Recode a number of FLACs to mp3, python, multiprocess, needs mpv, flac, metaflac and lame

flac-recode-mp3.py

#!/usr/bin/env python3
# coding=UTF-8

from os import system, cpu_count, getpid
from os.path import isfile, split, splitext, join
from sys import argv, exit, stderr
from re import sub
from subprocess import call
from multiprocessing import Pool
from traceback import print_exc

def recode_(f):
    assert isfile(f)
    fh, ft = split(f)
    r=splitext(ft)[0]
    rout = join(fh, sub("[<>+#'´`\"%$!=~;|^°(),*:\\\[\]\{\}]", "_", r))
    t = rout + ".tags"
    w = rout + ".wav"
    mp3 = rout + ".mp3"
    pid = getpid()

    def call_(argv):
        print("%5d>    %s" % (pid, " ".join(argv)))
        return call(argv)

    def C(*argv):
        a = []
        for i in argv:
            if type(i) == type([]):
                a += i
            else:
                a.append(i)
        return call_(a)

    if not isfile(mp3):
        assert C("metaflac", "--export-tags-to=" + t, f) == 0
        assert C("mpv", "--quiet", "--no-terminal", "--no-video", "--ao", "pcm", "--ao-pcm-file=" + w, f) == 0

        comments={}
        with open(t) as tags:
            for l in tags:
                if not l.startswith("REPLAYGAIN"):
                    k, v = l.strip().split('=', 2)
                    comments[k] = v

        def get(n, x):
            return comments.get(n, comments.get(n.lower(), x))

        if C("lame", "--quiet", "-q", "0", "-v", "-V", "0", # "--strictly-enforce-ISO",
                 "--tt", get("TITLE", "notitle"),
                 "--ta", get("ARTIST", "noartist"),
                 "--tl", get("ALBUM", "noalbum"),
                 "--tn", get("TRACKNUMBER", "0"),
                 w, mp3) != 0:
            return

    C("rm", "-f", t, w)

def recode(f):
    try:
        recode_(f)
    except:
        print_exc()

def main():
    with Pool(cpu_count() * 3 // 2) as p:
        p.map(recode, argv[1:])

__name__ == '__main__' and main()