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# Convert FLAC to MP3 using the CLI


If you've downloaded an album from your favorite artist in a lossless format like FLAC but need to produce MP3 files so you can use them in a portable player or upload them to a music service, you can use a little Bash scripting and some CLI tools to convert the files quickly.

In this tutorial you'll use the [flac](https://xiph.org/flac/) and [lame](https://lame.sourceforge.io/) command-line tools to transcode the files. You'll write a Bash script to capture the metadata from the FLAC file and add it to the MP3 you create.

## What You Need

To complete this tutorial on macOS, you'll need Homebrew installed, which you can do by following the [Install Homebrew]({{< ref "homebrew" >}}) tutorial.

## Installing the Tools

You'll need both the `flac` and `lame` command-line tools.

On macOS, you can use [Homebrew]({{< ref "homebrew" >}}) to install `flac` with the following command:

```command
brew install flac
```

To install `lame`, execute this command:

```command
brew install lame
```

On Ubuntu, you'll use the `apt` package manager to install both. First update your list of sources:

```command
sudo apt update
```

Then install both `flac` and `lame`:

```command
sudo apt install -y lame  flac
```

With both tools installed, you can write a script to decode the FLAC file and convert it to an MP3.

## Creating the Script

Create the file `~/bin/flac2mp3` and add the following contents to the file which read through a list of files, extract any metadata from the files, and convert the file to an MP3:

```bash
#!/usr/bin/env bash

for f in "$@"
do
    [[ "$f" != *.flac ]] && continue
    album="$(metaflac --show-tag=album "$f" | sed 's/[^=]*=//')"
    artist="$(metaflac --show-tag=artist "$f" | sed 's/[^=]*=//')"
    date="$(metaflac --show-tag=date "$f" | sed 's/[^=]*=//')"
    title="$(metaflac --show-tag=title "$f" | sed 's/[^=]*=//')"
    year="$(metaflac --show-tag=date "$f" | sed 's/[^=]*=//')"
    genre="$(metaflac --show-tag=genre "$f" | sed 's/[^=]*=//')"
    tracknumber="$(metaflac --show-tag=tracknumber "$f" | sed 's/[^=]*=//')"
    flac --decode --stdout "$f" | lame --preset extreme --add-id3v2 --tt "$title" --ta "$artist" --tl "$album" --ty "$year" --tn "$tracknumber" --tg "$genre" - "${f%.flac}.mp3"
done
```

The script loops over all of the arguments passed in, which should be a list of files. It then extracts the metadata like the title, artist, and track number from existing information in the FLAC file. It then decodes the file and sends the output to `lame`, using the extracted metadata as inputs. The new file will be saved with the same name, but with the `.mp3` extension.

Save the file.

Now make the script executable so you can run it without specifying the interpreter:

```command
chmod +x ~/bin/flac2mp3
```

You can now try out the script on some FLAC files.

## Converting the Files

Run the script on a Flac file by passing the file to the script you created:

```command
~/bin/flac2mp3 myfile.flac
```

This produces an MP3 file with the metadata preserved:

```output
flac 1.3.4
Copyright (C) 2000-2009  Josh Coalson, 2011-2016  Xiph.Org Foundation
flac comes with ABSOLUTELY NO WARRANTY.  This is free software, and you are
welcome to redistribute it under certain conditions.  Type `flac' for details.

myfile.flac: done
LAME 3.100 64bits (http://lame.sf.net)
polyphase lowpass filter disabled
Encoding <stdin> to myfile.mp3
Encoding as 44.1 kHz j-stereo MPEG-1 Layer III VBR(q=0)
```

The script supports multiple files too, so you can pass them by separating each file with a space:

```command
~/bin/flac2mp3 myfile.flac my_other_file.flac
```

If you have a whole directory of files to convert, this can be cumbersome. Instead of passing every file in manually, use the `find` command with its `-exec` argument to build up the file list:

```command
find . -name "*.flac" -exec bash ~/bin/flac2mp3 {} +
```

This searches for all the `flac` files in the current directory and uses the `-exec` option to run the script.  The `{}` symbols are the placeholder for the filename to use, and the `+` sign combines the arguments into a single argument rather than running the script once per file. Remember, the script accepts multiple files.

## Conclusion

Converting `flac` files to the MP3 format improves compatibility with devices. Using open-source tools, you can control the quality of the output files you create.