Add autobpm plugin

This plugin uses librosa to automatically calculate the BPM for a track.
It is based on the keyfinder plugin, and rounds the BPM to an int.

Co-authored-by: Adrian Sampson <adrian@radbox.org>

beetsplug/autobpm.py

@@ -0,0 +1,80 @@
+# This file is part of beets.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+
+"""Uses Librosa to calculate the `bpm` field.
+"""
+
+
+from beets import ui
+from beets import util
+from beets.plugins import BeetsPlugin
+
+from librosa import load, beat
+from soundfile import LibsndfileError
+
+
+class AutoBPMPlugin(BeetsPlugin):
+
+    def __init__(self):
+        super().__init__()
+        self.config.add({
+            'auto': True,
+            'overwrite': False,
+        })
+
+        if self.config['auto'].get(bool):
+            self.import_stages = [self.imported]
+
+    def commands(self):
+        cmd = ui.Subcommand('autobpm',
+                            help='detect and add bpm from audio using Librosa')
+        cmd.func = self.command
+        return [cmd]
+
+    def command(self, lib, opts, args):
+        self.calculate_bpm(lib.items(ui.decargs(args)),
+                           write=ui.should_write())
+
+    def imported(self, session, task):
+        self.calculate_bpm(task.imported_items())
+
+    def calculate_bpm(self, items, write=False):
+        overwrite = self.config['overwrite'].get(bool)
+
+        for item in items:
+            if item['bpm']:
+                self._log.info('found bpm {0} for {1}',
+                               item['bpm'], util.displayable_path(item.path))
+                if not overwrite:
+                    continue
+
+            try:
+                y, sr = load(util.syspath(item.path), res_type='kaiser_fast')
+            except LibsndfileError as exc:
+                self._log.error('LibsndfileError: failed to load {0} {1}',
+                                util.displayable_path(item.path), exc)
+                continue
+            except ValueError as exc:
+                self._log.error('ValueError: failed to load {0} {1}',
+                                util.displayable_path(item.path), exc)
+                continue
+
+            tempo, _ = beat.beat_track(y=y, sr=sr)
+            bpm = round(tempo)
+            item['bpm'] = bpm
+            self._log.info('added computed bpm {0} for {1}',
+                           bpm, util.displayable_path(item.path))
+
+            if write:
+                item.try_write()
+            item.store()

docs/changelog.rst

@@ -122,6 +122,9 @@ New features:
   :bug:`2786`
 * Add support for ``artists`` and ``albumartists`` multi-valued tags.
   :bug:`505`
+* :doc:`/plugins/autobpm`: Add the `autobpm` plugin which uses Librosa to
+  calculate the BPM of the audio.
+  :bug:`3856`
 
 Bug fixes:
 

docs/plugins/autobpm.rst

@@ -0,0 +1,25 @@
+AutoBPM Plugin
+==============
+
+The `autobpm` plugin uses the `Librosa`_ library to calculate the BPM
+of a track from its audio data and store it in the `bpm` field of your
+database. It does so automatically when importing music or through
+the ``beet autobpm [QUERY]`` command.
+
+To use the ``autobpm`` plugin, enable it in your configuration (see
+:ref:`using-plugins`).
+
+Configuration
+-------------
+
+To configure the plugin, make a ``autobpm:`` section in your
+configuration file. The available options are:
+
+- **auto**: Analyze every file on import.
+  Otherwise, you need to use the ``beet autobpm`` command explicitly.
+  Default: ``yes``
+- **overwrite**: Calculate a BPM even for files that already have a
+  `bpm` value.
+  Default: ``no``.
+
+.. _Librosa: https://github.com/librosa/librosa/

docs/plugins/index.rst

@@ -63,6 +63,7 @@ following to your configuration::
    acousticbrainz
    albumtypes
    aura
+   autobpm
    badfiles
    bareasc
    beatport
@@ -164,6 +165,9 @@ Metadata
 :doc:`acousticbrainz <acousticbrainz>`
    Fetch various AcousticBrainz metadata
 
+:doc:`autobpm <autobpm>`
+   Use `Librosa`_ to calculate the BPM from the audio.
+
 :doc:`bpm <bpm>`
    Measure tempo using keystrokes.
 
@@ -222,6 +226,7 @@ Metadata
 :doc:`zero <zero>`
    Nullify fields by pattern or unconditionally.
 
+.. _Librosa: https://github.com/librosa/librosa/
 .. _KeyFinder: http://www.ibrahimshaath.co.uk/keyfinder/
 .. _streaming_extractor_music: https://acousticbrainz.org/download
 

setup.cfg

@@ -32,6 +32,7 @@ per-file-ignores =
     ./extra/release.py:D
     ./beetsplug/duplicates.py:D
     ./beetsplug/bpm.py:D
+    ./beetsplug/autobpm.py:D
     ./beetsplug/convert.py:D
     ./beetsplug/info.py:D
     ./beetsplug/parentwork.py:D