Convert directory to mp3 recursively

inplace_convert_dir_to_mp3.pl

# Convert files to mp3 recursively using ffmpeg, destroying originals
# FIXME fails on unicode chars
# FIXME should work on flac/wav rather than only high-bitrate mp3s

use strict;
use warnings;
use File::Copy;
use File::Find;

my $verbose = 0;
my $target_bitrate = 128;

# any mp3s above this bitrate will be converted to $target_bitrate
my $threshold_bitrate = 160; 

sub process {
    if (-f $_ && $_ =~ /\.mp3$/i) {
        my $file = $_;
        my $info = `ffmpeg -i \"$file\" 2>&1`;
        $info =~ /^\s*Stream.+Audio: mp3.+?(\d+) kb\/s$/m;

        return if $1 <= $threshold_bitrate;

        print "$file\n" if $verbose;
        my $cmd = "ffmpeg -i \"$file\" -hide_banner -loglevel warning -vn ".
                  "-write_id3v1 1 -id3v2_version 3 ".
                  "-b:a ${target_bitrate}k \"____$file\"";
        system($cmd) == 0 or die "$0: [$cmd] failed: $?\n";
        move("____$file", $file) or die "move failed: $!";
    }
}

find(\&process, $ARGV[0] || ".");