Convert FLAC to MP3

Here are a few scripts and tools that facilitate converting FLAC to MP3.

Introduction

For more information on LAME switches/settings such as V0, visit the Hydrogenaudio LAME Wiki. V0 is roughly equivalent to --preset extreme which results in a variable bitrate usually between 220-260. The audio of a V0 is transparent, meaning one cannot tell the difference between the lossy file and the original source (compact disc/lossless), but yet the file size is a quite reasonable.

More information on FLAC: FLAC

Scripts

In these two examples, the FLAC files in a directory are read, decompressed to WAV, and streamed into the MP3 encoder, LAME. Both scripts pass the ID3 tags from the FLAC files to the resulting MP3 files, and encode to MP3 V0.

The original .flac files are not modified and the resulting .mp3s will be in the same directory. All files with extensions not matching *.flac in the working directory (.nfo, images, .sfv, etc.) are ignored.

With FFmpeg

Chances are, your system already has ffmpeg installed, which brings in the flac and lame packages. FFmpeg has all the encoding and decoding facilities built in to do the job.

#!/bin/bash

for f in *.flac; do
  ffmpeg -i "$f" -qscale:a 0 "${f[@]/%flac/mp3}"
done

Without FFmpeg

If for some reason you have something against ffmpeg, you still need to have flac and lame installed. Here, the tagging process is more explicit, using the metadata utility that comes with flac, and passing the information to lame

#!/bin/bash

for a in *.flac; do
  # give output correct extension
  OUTF="${a[@]/%flac/mp3}"

  # get the tags
  ARTIST=$(metaflac "$a" --show-tag=ARTIST | sed s/.*=//g)
  TITLE=$(metaflac "$a" --show-tag=TITLE | sed s/.*=//g)
  ALBUM=$(metaflac "$a" --show-tag=ALBUM | sed s/.*=//g)
  GENRE=$(metaflac "$a" --show-tag=GENRE | sed s/.*=//g)
  TRACKNUMBER=$(metaflac "$a" --show-tag=TRACKNUMBER | sed s/.*=//g)
  DATE=$(metaflac "$a" --show-tag=DATE | sed s/.*=//g)

  # stream flac into the lame encoder
  flac -c -d "$a" | lame -V0 --add-id3v2 --pad-id3v2 --ignore-tag-errors \
    --ta "$ARTIST" --tt "$TITLE" --tl "$ALBUM"  --tg "${GENRE:-12}" \
    --tn "${TRACKNUMBER:-0}" --ty "$DATE" - "$OUTF"
done

Usage

For ease of use, add the script to your PATH. Open up a terminal, cd to the directory of FLAC files that you wish to convert, and invoke flac2mp3 (or whatever you named the script). You'll see the verbose decoding/encoding process in the terminal which may take a few moments. Done!!! At this point, it's trivial to mv *.mp3 all your new MP3s wherever you wish.

A useful extension of the above scripts is to let it recurse into all subdirectories of the working directory. Replace the first line (for .... do) with

find -type f -name "*.flac" -print0 | while read -d $'\0' a; do

Packages

• whatmp3^AUR A small Python script that accepts a list of directories containing FLAC files as arguments and converts them to MP3 with the specified options.
• flac2all^AUR Audio converter of FLAC to either Ogg Vorbis or MP3 retaining all tags and metadata
• flac2mp3-bash^AUR Bash script to convert Flac to Mp3 easily

Related Links

• https://www.xiph.org/flac/
• https://en.wikipedia.org/wiki/FLAC
• http://lame.sourceforge.net/