Early stage pipeline plugin functions

beets/importer.py

@@ -313,6 +313,8 @@ def run(self):
                 stages += [import_asis(self)]
 
             # Plugin stages.
+            for stage_func in plugins.early_import_stages():
+                stages.append(plugin_stage(self, stage_func))
             for stage_func in plugins.import_stages():
                 stages.append(plugin_stage(self, stage_func))
 

beets/plugins.py

@@ -81,6 +81,7 @@ def __init__(self, name=None):
             self.template_fields = {}
         if not self.album_template_fields:
             self.album_template_fields = {}
+        self.early_import_stages = []
         self.import_stages = []
 
         self._log = log.getChild(self.name)
@@ -94,6 +95,22 @@ def commands(self):
         """
         return ()
 
+    def _set_stage_log_level(self, stages):
+        """Adjust all the stages in `stages` to WARNING logging level.
+        """
+        return [self._set_log_level_and_params(logging.WARNING, stage)
+                for stage in stages]
+
+    def get_early_import_stages(self):
+        """Return a list of functions that should be called as importer
+        pipelines stages early in the pipeline.
+
+        The callables are wrapped versions of the functions in
+        `self.early_import_stages`. Wrapping provides some bookkeeping for the
+        plugin: specifically, the logging level is adjusted to WARNING.
+        """
+        return self._set_stage_log_level(self.early_import_stages)
+
     def get_import_stages(self):
         """Return a list of functions that should be called as importer
         pipelines stages.
@@ -102,8 +119,7 @@ def get_import_stages(self):
         `self.import_stages`. Wrapping provides some bookkeeping for the
         plugin: specifically, the logging level is adjusted to WARNING.
         """
-        return [self._set_log_level_and_params(logging.WARNING, import_stage)
-                for import_stage in self.import_stages]
+        return self._set_stage_log_level(self.import_stages)
 
     def _set_log_level_and_params(self, base_log_level, func):
         """Wrap `func` to temporarily set this plugin's logger level to
@@ -393,6 +409,14 @@ def template_funcs():
     return funcs
 
 
+def early_import_stages():
+    """Get a list of early import stage functions defined by plugins."""
+    stages = []
+    for plugin in find_plugins():
+        stages += plugin.get_early_import_stages()
+    return stages
+
+
 def import_stages():
     """Get a list of import stage functions defined by plugins."""
     stages = []

beetsplug/convert.py

@@ -146,7 +146,7 @@ def __init__(self):
             u'copy_album_art': False,
             u'album_art_maxwidth': 0,
         })
-        self.import_stages = [self.auto_convert]
+        self.early_import_stages = [self.auto_convert]
 
         self.register_listener('import_task_files', self._cleanup)
 

docs/changelog.rst

@@ -46,6 +46,11 @@ Fixes:
 * Avoid a crash when importing a non-ASCII filename when using an ASCII locale
   on Unix under Python 3.
   :bug:`2793` :bug:`2803`
+* Convert plugin now runs before all others in the pipeline to solve an issue
+  with generating ReplayGain data incompatible between the source and target
+  file formats. This option to request (part of) your plugin to run early in the
+  pipeline has been exposed in the plugin API as well (```early_import_stages```).
+  Thanks to :user:`autrimpo`.
 
 
 1.4.6 (December 21, 2017)

docs/dev/plugins.rst

@@ -432,6 +432,11 @@ to register it::
         def stage(self, session, task):
             print('Importing something!')
 
+It is also possible to request your function to run early in the pipeline by
+adding the function to the plugin's ``early_import_stages`` field instead.::
+
+  self.early_import_stages = [self.stage]
+
 .. _extend-query:
 
 Extend the Query Syntax