Replaygain backend r128gain

beetsplug/replaygain.py

@@ -88,6 +88,10 @@ def compute_album_gain(self, album):
         # individual tracks which can be used for any backend.
         raise NotImplementedError()
 
+    def use_ebu_r128(self):
+        """Set this Backend up to use EBU R128."""
+        pass
+
 
 # bsg1770gain backend
 class Bs1770gainBackend(Backend):
@@ -271,6 +275,10 @@ def end_element_handler(name):
             out.append(album_gain["album"])
         return out
 
+    def use_ebu_r128(self):
+        """Set this Backend up to use EBU R128."""
+        self.method = '--ebu'
+
 
 # mpgain/aacgain CLI tool backend.
 class CommandBackend(Backend):
@@ -813,6 +821,71 @@ def compute_album_gain(self, album):
         )
 
 
+# r128gain (https://github.com/desbma/r128gain) backend
+class R128gainBackend(Backend):
+    """r128gain (https://github.com/desbma/r128gain) ReplayGain backend.
+
+    Provides a Backend to the replaygain plugin using the r128gain python
+    module.
+    """
+
+    def __init__(self, config, log):
+        super(R128gainBackend, self).__init__(config, log)
+        self.__import_r128gain()
+
+    def __import_r128gain(self):
+        """Try to import the r128gain module to self._mod_r128gain.
+        """
+        try:
+            import r128gain
+        except ImportError:
+            raise FatalReplayGainError(
+                u"failed to load r128gain: please install r128gain"
+            )
+        self._mod_r128gain = r128gain
+
+    def compute_track_gain(self, items):
+        """Computes the track gain of the given tracks, returns a list
+        of Gain objects (the track gains).
+        """
+        gains, album_gain = self.compute_gain(items, False)
+        return gains
+
+    def compute_album_gain(self, album):
+        """Computes the album gain of the given album, returns an
+        AlbumGain object.
+        """
+        items = album.items()
+        gains, album_gain = self.compute_gain(items, True)
+        return AlbumGain(album_gain, gains)
+
+    def compute_gain(self, items, is_album):
+        """Computes the track (and optionally album gain) of a list of
+        items, returns a pair of a list of Gain objects (the track gains)
+        and a optional Gain object (the album gain).
+        """
+        # scan files
+        paths = [i.path.decode() for i in items]
+        self._log.debug(u"scanning {0} with r128gain".format(paths))
+        output = self._mod_r128gain.scan(paths, album_gain=is_album)
+
+        # track gains
+        try:
+            gains = [Gain(*output[path]) for path in paths]
+        except KeyError as e:
+            raise ReplayGainError(u"failed to analyse file: {0}".format(e))
+
+        # album gain
+        album_gain_key = self._mod_r128gain.ALBUM_GAIN_KEY
+        album_gain = output.pop(album_gain_key, None)
+        if is_album:
+            if album_gain is None:
+                raise ReplayGainError(u"failed to analyse album")
+            album_gain = Gain(*album_gain)
+
+        return gains, album_gain
+
+
 # Main plugin logic.
 
 class ReplayGainPlugin(BeetsPlugin):
@@ -824,8 +897,11 @@ class ReplayGainPlugin(BeetsPlugin):
         "gstreamer": GStreamerBackend,
         "audiotools": AudioToolsBackend,
         "bs1770gain": Bs1770gainBackend,
+        "r128gain": R128gainBackend,
     }
 
+    r128_backend_names = ["bs1770gain", "r128gain"]
+
     def __init__(self):
         super(ReplayGainPlugin, self).__init__()
 
@@ -1009,7 +1085,9 @@ def handle_track(self, item, write, force=False):
                 u"Fatal replay gain error: {0}".format(e))
 
     def init_r128_backend(self):
-        backend_name = 'bs1770gain'
+        backend_name = self.config["backend"].as_str()
+        if backend_name not in self.r128_backend_names:
+            backend_name = "bs1770gain"
 
         try:
             self.r128_backend_instance = self.backends[backend_name](
@@ -1019,7 +1097,7 @@ def init_r128_backend(self):
             raise ui.UserError(
                 u'replaygain initialization failed: {0}'.format(e))
 
-        self.r128_backend_instance.method = '--ebu'
+        self.r128_backend_instance.use_ebu_r128()
 
     def imported(self, session, task):
         """Add replay gain info to items or albums of ``task``.

docs/plugins/replaygain.rst

@@ -10,10 +10,10 @@ playback levels.
 Installation
 ------------
 
-This plugin can use one of four backends to compute the ReplayGain values:
-GStreamer, mp3gain (and its cousin, aacgain), Python Audio Tools and bs1770gain. mp3gain
-can be easier to install but GStreamer, Audio Tools and bs1770gain support more audio
-formats.
+This plugin can use one of five backends to compute the ReplayGain values:
+GStreamer, mp3gain (and its cousin, aacgain), Python Audio Tools, bs1770gain and
+r128gain. mp3gain can be easier to install but GStreamer, Audio Tools, bs1770gain
+and r128gain support more audio formats.
 
 Once installed, this plugin analyzes all files during the import process. This
 can be a slow process; to instead analyze after the fact, disable automatic
@@ -94,6 +94,20 @@ For Windows users: the tool currently has issues with long and non-ASCII path
 names. You may want to use the :ref:`asciify-paths` configuration option until
 this is resolved.
 
+r128gain
+````````
+
+This backend uses the python module `r128gain`_. It can be installed from PyPI::
+
+    pip3 install r128gain
+
+Also see the `r128gain installation`_ page.
+Please note that `r128gain`_ describes itself as "beta software", this backend
+could possibly break.
+
+.. _r128gain: https://github.com/desbma/r128gain
+.. _r128gain installation: https://github.com/desbma/r128gain/blob/master/README.md#installation
+
 Configuration
 -------------
 
@@ -110,7 +124,7 @@ configuration file. The available options are:
   Default: 89.
 - **r128**: A space separated list of formats that will use ``R128_`` tags with
   integer values instead of the common ``REPLAYGAIN_`` tags with floating point
-  values. Requires the "bs1770gain" backend.
+  values. Requires the "bs1770gain" or "r128gain" backend.
   Default: ``Opus``.
 
 These options only work with the "command" backend:

test/test_replaygain.py

@@ -43,6 +43,12 @@
 else:
     LOUDNESS_PROG_AVAILABLE = False
 
+try:
+    import r128gain
+    R128GAIN_AVAILABLE = hasattr(r128gain, 'scan')
+except ImportError:
+    R128GAIN_AVAILABLE = False
+
 
 class ReplayGainCliTestBase(TestHelper):
 
@@ -166,6 +172,11 @@ class ReplayGainLdnsCliTest(ReplayGainCliTestBase, unittest.TestCase):
     backend = u'bs1770gain'
 
 
+@unittest.skipIf(not R128GAIN_AVAILABLE, u'r128gain cannot be found')
+class ReplayGainR128gainCliTest(ReplayGainCliTestBase, unittest.TestCase):
+    backend = u'r128gain'
+
+
 def suite():
     return unittest.TestLoader().loadTestsFromName(__name__)