Normalized Audio in mplayer

[b-berry]

Overview:
Build in normalized audio for all assets containing audio playback across the LG.

Either:
Run normalization at post asset file upload

• Benefit: One time process
  Run normalization during any mplayer activity
• mplayer -af volnorm=2:0.75 foo_asset like:

bryan@b3erry-ephq:~/src/lg_ros_nodes$ git diff
diff --git a/lg_media/src/lg_media/mplayer_pool.py b/lg_media/src/lg_media/mplayer_pool.py
index df5e106..e0dd72f 100755
--- a/lg_media/src/lg_media/mplayer_pool.py
+++ b/lg_media/src/lg_media/mplayer_pool.py
@@ -18,7 +18,7 @@ from lg_common.helpers import get_app_instances_to_manage
 
 ROS_NODE_NAME = "lg_media"
 DEFAULT_APP = "mplayer"
-DEFAULT_ARGS = "-idle -slave -cache 256 -quiet -osdlevel 0 -nomouseinput -nograbpointer"
+DEFAULT_ARGS = "-idle -slave -cache 256 -quiet -osdlevel 0 -af volnorm=2:0.75 -nomouseinput -nograbpointer"
 SRV_QUERY = '/'.join(('', ROS_NODE_NAME, "query"))

Goal:
Maintain highest performance possible while normalizing software audio levels.

More info:

near:114116 stream:LG+R&D topic:Mplayer+Audio+Normalization
https://chat.endpoint.com/#narrow/near/114116/stream/LG.20R.26D/topic/Mplayer.20Audio.20Normalization

[wzin]

This issue is really kewl. Related to #350