make operators more local to each queue source

python_apps/pypo/liquidsoap_scripts/ls_script.liq

@@ -40,6 +40,13 @@ source_id = ref 0
 def create_source()
     l = request.equeue(id="s#{!source_id}", length=0.5)
     l = cue_cut(l)
+
+    l = audio_to_stereo(id="queue_src", l)
+    l = amplify(1., override="replay_gain", l)
+
+    # the crossfade function controls fade in/out
+    l = crossfade_airtime(l)
+
     l = on_metadata(notify, l)
     sources := list.append([l], !sources)
     server.register(namespace="queues",
@@ -63,11 +70,6 @@ create_source()
 
 queue = add(!sources, normalize=false)
 
-queue = audio_to_stereo(id="queue_src", queue)
-queue = amplify(1., override="replay_gain", queue)
-
-# the crossfade function controls fade in/out
-queue = crossfade_airtime(queue)
 output.dummy(fallible=true, queue)
 
 http = input.http_restart(id="http")