Convert Flac to Mp3

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Revision as of 19:58, 23 March 2014 by Neitsab (Talk | contribs) (Restructuring and addition of a few graphical apps besides pure CLI/script methods.)

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This article presents ways of doing audio transcoding between FLAC and MP3 audio files using command line/scripted tools, and suggest a few graphical utilities to do the same and more.

Scripts

In these two examples, FLAC files in current directory are read and streamed into the LAME MP3 encoder. Both scripts pass the ID3 tags from the FLAC files to the resulting MP3 files, and encode to MP3 V0. V0 is equivalent to --preset extreme which results in a variable bitrate usually between 220-260 kbps. The audio of a V0 file 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 lower. For more information on LAME switches/settings such as V0, visit the Hydrogenaudio LAME Wiki.

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

Parallel version

Conversion can be accelerated if you have multicore CPU/several CPUs:

parallel -j 4 'a={}; ffmpeg -i "$a" -qscale:a 0 "${a[@]/%flac/mp3}"' ::: *.flac

Without FFmpeg

If for some reason FFmpeg isn't installed and you don't want to install it, 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. The process duration will slightly increase since FLACs must first be decoded to WAVE and then fed into the MP3 encoder.

#!/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

Recursively

A useful extension of the above scripts is to let them recurse into all subdirectories of the working directory. To do so, replace the first line (for .... do) with:

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

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.

Packages

  • whatmp3AUR - A small Python script that accepts a list of directories containing FLAC files as arguments and converts them to MP3 with the specified options.
  • flac2allAUR - Audio converter of FLAC to either Ogg Vorbis or MP3 retaining all tags and metadata.
  • flac2mp3-bashAUR - Bash script to convert Flac to Mp3 easily.

Graphical applications

  • SoundConverter — A dedicated audio transcoding utility built for the GNOME desktop and relying on GStreamer. It can make use of GNOME Audio Profiles and features multithreaded conversions. It can also extract the audio from videos.
http://soundconverter.org/ || soundconverter
  • soundKonverter — A Qt graphical frontend to various audio manipulation programs. Features conversion, ripping and other audio manipulation functionalities.
https://github.com/HessiJames/soundkonverter/wiki || soundkonverter
  • WinFF — A GUI for the powerful multimedia converter FFmpeg. Features dedicated profiles for audio transcoding.
http://code.google.com/p/winff/ || winff

See also