Merge pull request #866 from aroquen/master

Detect BPM from keystrokes

beetsplug/bpm.py

@@ -0,0 +1,87 @@
+# This file is part of beets.
+# Copyright 2014, aroquen
+#
+# 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.
+
+"""Determine BPM by pressing a key to the rhythm."""
+
+import time
+import logging
+
+from beets import ui
+from beets.plugins import BeetsPlugin
+
+log = logging.getLogger('beets')
+
+
+def bpm(max_strokes):
+    """Returns average BPM (possibly of a playing song)
+    listening to Enter keystrokes.
+    """
+    t0 = None
+    dt = []
+    for i in range(max_strokes):
+        # Press enter to the rhythm...
+        s = raw_input()
+        if s == '':
+            t1 = time.time()
+            # Only start measuring at the second stroke
+            if t0:
+                dt.append(t1 - t0)
+            t0 = t1
+        else:
+            break
+
+    # Return average BPM
+    # bpm = (max_strokes-1) / sum(dt) * 60
+    ave = sum([1.0 / dti * 60 for dti in dt]) / len(dt)
+    return ave
+
+
+class BPMPlugin(BeetsPlugin):
+
+    def __init__(self):
+        super(BPMPlugin, self).__init__()
+        self.config.add({
+            u'max_strokes': 3,
+            u'overwrite': True,
+        })
+
+    def commands(self):
+        cmd = ui.Subcommand('bpm',
+                            help='determine bpm of a song by pressing \
+                            a key to the rhythm')
+        cmd.func = self.command
+        return [cmd]
+
+    def command(self, lib, opts, args):
+        self.get_bpm(lib.items(ui.decargs(args)))
+
+    def get_bpm(self, items, write=False):
+        overwrite = self.config['overwrite'].get(bool)
+        if len(items) > 1:
+            raise ValueError('Can only get bpm of one song at time')
+
+        item = items[0]
+        if item['bpm']:
+            log.info('Found bpm {0}'.format(item['bpm']))
+            if not overwrite:
+                return
+
+        log.info('Press Enter {0} times to the rhythm or Ctrl-D \
+to exit'.format(self.config['max_strokes'].get(int)))
+        new_bpm = bpm(self.config['max_strokes'].get(int))
+        item['bpm'] = int(new_bpm)
+        if write:
+            item.try_write()
+        item.store()
+        log.info('Added new bpm {0}'.format(item['bpm']))

docs/plugins/bpm.rst

@@ -0,0 +1,22 @@
+BPM Plugin
+==========
+
+This ``bpm`` plugin allows to determine the bpm (beats per minute) of a song by recording the user's keystrokes. The rationale is that sometimes the bpm of a song cannot be obtained from the echonest database (via the ``echonest`` plugin) or it is simply plain wrong. Whenever you need to fix the bpm of a song manually, the ``bpm`` plugin comes to the rescue.
+
+Usage
+------
+
+First, enable the plugin ``bpm`` as described in :doc:`/plugins/index`. Then, suppose you want to set or modify the bpm of ``<song>``, where ``<song>`` is any valid query that matches the song of interest. Start playing it with your favorite media player, fire up a terminal and type::
+
+     beet bpm <song> 
+
+You'll be prompted to press Enter three times to the rhythm. This typically allows to determine the bpm within 5% accuracy. 
+
+The plugin works best if you wrap it in a script that gets the playing song, for instance with ``mpc`` you can do something like::
+
+     beet bpm $(mpc |head -1|tr -d "-")
+
+Credit
+------
+
+This plugin is inspired by a similar feature present in the Banshee media player.

docs/plugins/index.rst

@@ -60,6 +60,7 @@ by typing ``beet version``.
    keyfinder
    bucket
    importadded
+   bpm
 
 Autotagger Extensions
 ---------------------
@@ -94,6 +95,7 @@ Metadata
   key from the audio.
 * :doc:`importadded`: Use file modification times for guessing the value for
   the `added` field in the database.
+* :doc:`bpm`: Determine bpm from keystrokes
 
 .. _Acoustic Attributes: http://developer.echonest.com/acoustic-attributes.html
 .. _the Echo Nest: http://www.echonest.com