[pitivi] project: Reuse logic for picking source caps

[Alexandru Băluț <alexbalut src gnome org>]

commit 8f74ce56a9f4c01366a271df019dcfb24c92d92f
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Mon Aug 1 00:22:35 2016 +0200

    project: Reuse logic for picking source caps
    
    Reviewed-by: Thibault Saunier <tsaunier gnome org>
    Differential Revision: https://phabricator.freedesktop.org/D1229

 pitivi/project.py |   52 +++++++++++++++++++++-------------------------------
 1 files changed, 21 insertions(+), 31 deletions(-)
---
diff --git a/pitivi/project.py b/pitivi/project.py
index 4acf539..f710a3d 100644
--- a/pitivi/project.py
+++ b/pitivi/project.py
@@ -876,17 +876,10 @@ class Project(Loggable, GES.Project):
     @aencoder.setter
     def aencoder(self, value):
         if self.audio_profile.get_preset_name() != value and value:
-            feature = Gst.Registry.get().lookup_feature(value)
-            if feature is None:
-                self.error("%s not in registry", value)
-            else:
-                for template in feature.get_static_pad_templates():
-                    if template.name_template == "src":
-                        audiotype = template.get_caps()[0].to_string()
-                        break
-                self.audio_profile.set_format(Gst.Caps(audiotype))
+            caps = self._get_caps_from_feature(value)
+            if caps:
+                self.audio_profile.set_format(caps)
             self.audio_profile.set_preset_name(value)
-
             self._emitChange("rendering-settings-changed", "aencoder", value)
 
     @property
@@ -896,18 +889,10 @@ class Project(Loggable, GES.Project):
     @vencoder.setter
     def vencoder(self, value):
         if self.video_profile.get_preset_name() != value and value:
-            feature = Gst.Registry.get().lookup_feature(value)
-            if feature is None:
-                self.error("%s not in registry", value)
-            else:
-                for template in feature.get_static_pad_templates():
-                    if template.name_template == "src":
-                        videotype = template.get_caps()[0].to_string()
-                        break
-                self.video_profile.set_format(Gst.Caps(videotype))
-
+            caps = self._get_caps_from_feature(value)
+            if caps:
+                self.video_profile.set_format(caps)
             self.video_profile.set_preset_name(value)
-
             self._emitChange("rendering-settings-changed", "vencoder", value)
 
     @property
@@ -917,19 +902,24 @@ class Project(Loggable, GES.Project):
     @muxer.setter
     def muxer(self, value):
         if self.container_profile.get_preset_name() != value and value:
-            feature = Gst.Registry.get().lookup_feature(value)
-            if feature is None:
-                self.error("%s not in registry", value)
-            else:
-                for template in feature.get_static_pad_templates():
-                    if template.name_template == "src":
-                        muxertype = template.get_caps()[0].to_string()
-                        break
-                self.container_profile.set_format(Gst.Caps(muxertype))
+            caps = self._get_caps_from_feature(value)
+            if caps:
+                self.container_profile.set_format(caps)
             self.container_profile.set_preset_name(value)
-
             self._emitChange("rendering-settings-changed", "muxer", value)
 
+    def _get_caps_from_feature(self, name):
+        """Gets the caps for the source static pad template of a feature."""
+        feature = Gst.Registry.get().lookup_feature(name)
+        if not feature:
+            self.error("%s not in registry", name)
+            return None
+        for template in feature.get_static_pad_templates():
+            if template.name_template == "src":
+                return Gst.Caps(template.get_caps()[0].to_string())
+        self.error("%s has no source static pad templates", name)
+        return None
+
     @property
     def render_scale(self):
         return self.get_meta("render-scale")