Convert Plugin#

The convert plugin lets you convert parts of your collection to a directory of your choice, transcoding audio and embedding album art along the way. It can transcode to and from any format using a configurable command line. Optionally an m3u playlist file containing all the converted files can be saved to the destination path.


To use the convert plugin, first enable it in your configuration (see Using Plugins). By default, the plugin depends on FFmpeg to transcode the audio, so you might want to install it.


To convert a part of your collection, run beet convert QUERY. The command will transcode all the files matching the query to the destination directory given by the -d (--dest) option or the dest configuration. The path layout mirrors that of your library, but it may be customized through the paths configuration. Files that have been previously converted—and thus already exist in the destination directory—will be skipped.

The plugin uses a command-line program to transcode the audio. With the -f (--format) option you can choose the transcoding command and customize the available commands through the configuration.

Unless the -y (--yes) flag is set, the command will list all the items to be converted and ask for your confirmation.

The -a (or --album) option causes the command to match albums instead of tracks.

By default, the command places converted files into the destination directory and leaves your library pristine. To instead back up your original files into the destination directory and keep converted files in your library, use the -k (or --keep-new) option.

To test your configuration without taking any actions, use the --pretend flag. The plugin will print out the commands it will run instead of executing them.

By default, files that do not need to be transcoded will be copied to their destination. Passing the -l (--link) flag creates symbolic links instead, passing -H (--hardlink) creates hard links. Note that album art embedding is disabled for files that are linked. Refer to the link and hardlink options below.

The -m (or --playlist) option enables the plugin to create an m3u8 playlist file in the destination folder given by the -d (--dest) option or the dest configuration. The path to the playlist file can either be absolute or relative to the dest directory. The contents will always be relative paths to media files, which tries to ensure compatibility when read from external drives or on computers other than the one used for the conversion. There is one caveat though: A list generated on Unix/macOS can’t be read on Windows and vice versa.

Depending on the beets user’s settings a generated playlist potentially could contain unicode characters. This is supported, playlists are written in M3U8 format.


To configure the plugin, make a convert: section in your configuration file. The available options are:

  • auto: Import transcoded versions of your files automatically during imports. With this option enabled, the importer will transcode all (in the default configuration) non-MP3 files over the maximum bitrate before adding them to your library. Default: no.

  • auto_keep: Convert your files automatically on import to dest but import the non transcoded version. It uses the default format you have defined in your config file. Default: no.


    You probably want to use only one of the auto and auto_keep options, not both. Enabling both will convert your files twice on import, which you probably don’t want.

  • tmpdir: The directory where temporary files will be stored during import. Default: none (system default),

  • copy_album_art: Copy album art when copying or transcoding albums matched using the -a option. Default: no.

  • album_art_maxwidth: Downscale album art if it’s too big. The resize operation reduces image width to at most maxwidth pixels while preserving the aspect ratio. The specified image size will apply to both embedded album art and external image files.

  • dest: The directory where the files will be converted (or copied) to. Default: none.

  • embed: Embed album art in converted items. Default: yes.

  • id3v23: Can be used to override the global id3v23 option. Default: inherit.

  • max_bitrate: By default, the plugin does not transcode files that are already in the destination format. This option instead also transcodes files with high bitrates, even if they are already in the same format as the output. Note that this does not guarantee that all converted files will have a lower bitrate—that depends on the encoder and its configuration. Default: none.

  • no_convert: Does not transcode items matching the query string provided (see Queries). For example, to not convert AAC or WMA formats, you can use format:AAC, format:WMA or path::\.(m4a|wma)$. If you only want to transcode WMA format, you can use a negative query, e.g., ^path::\.(wma)$, to not convert any other format except WMA.

  • never_convert_lossy_files: Cross-conversions between lossy codecs—such as mp3, ogg vorbis, etc.—makes little sense as they will decrease quality even further. If set to yes, lossy files are always copied. Default: no.

  • paths: The directory structure and naming scheme for the converted files. Uses the same format as the top-level paths section (see Path Format Configuration). Default: Reuse your top-level path format settings.

  • quiet: Prevent the plugin from announcing every file it processes. Default: false.

  • threads: The number of threads to use for parallel encoding. By default, the plugin will detect the number of processors available and use them all.

  • link: By default, files that do not need to be transcoded will be copied to their destination. This option creates symbolic links instead. Note that options such as embed that modify the output files after the transcoding step will cause the original files to be modified as well if link is enabled. For this reason, album-art embedding is disabled for files that are linked. Default: false.

  • hardlink: This options works similar to link, but it creates hard links instead of symlinks. This option overrides link. Only works when converting to a directory on the same filesystem as the library. Default: false.

  • delete_originals: Transcoded files will be copied or moved to their destination, depending on the import configuration. By default, the original files are not modified by the plugin. This option deletes the original files after the transcoding step has completed. Default: false.

  • playlist: The name of a playlist file that should be written on each run of the plugin. A relative file path (e.g playlists/mylist.m3u8) is allowed as well. The final destination of the playlist file will always be relative to the destination path (dest, --dest, -d). This configuration is overridden by the -m (--playlist) command line option. Default: none.

You can also configure the format to use for transcoding (see the next section):

  • format: The name of the format to transcode to when none is specified on the command line. Default: mp3.

  • formats: A set of formats and associated command lines for transcoding each.

Configuring the transcoding command#

You can customize the transcoding command through the formats map and select a command with the --format command-line option or the format configuration.

    format: speex
            command: ffmpeg -i $source -y -acodec speex $dest
            extension: spx
        wav: ffmpeg -i $source -y -acodec pcm_s16le $dest

In this example beet convert will use the speex command by default. To convert the audio to wav, run beet convert -f wav. This will also use the format key (wav) as the file extension.

Each entry in the formats map consists of a key (the name of the format) as well as the command and optionally the file extension. extension is the filename extension to be used for newly transcoded files. If only the command is given as a string or the extension is not provided, the file extension defaults to the format’s name. command is the command to use to transcode audio. The tokens $source and $dest in the command are replaced with the paths to the existing and new file.

The plugin in comes with default commands for the most common audio formats: mp3, alac, flac, aac, opus, ogg, wma. For details have a look at the output of beet config -d.

For a one-command-fits-all solution use the convert.command and convert.extension options. If these are set, the formats are ignored and the given command is used for all conversions.

    command: ffmpeg -i $source -y -vn -aq 2 $dest
    extension: mp3

Gapless MP3 encoding#

While FFmpeg cannot produce “gapless” MP3s by itself, you can create them by using LAME directly. Use a shell script like this to pipe the output of FFmpeg into the LAME tool:

ffmpeg -i "$1" -f wav - | lame -V 2 --noreplaygain - "$2"

Then configure the convert plugin to use the script:

    command: /path/to/ $source $dest
    extension: mp3

This strategy configures FFmpeg to produce a WAV file with an accurate length header for LAME to use. Using --noreplaygain disables gain analysis; you can use the ReplayGain Plugin to do this analysis. See the LAME documentation and the HydrogenAudio wiki for other LAME configuration options and a thorough discussion of MP3 encoding.