22-SEP-2019 Matthew J. Wolf Email: matthew.wolf at speciosus.net

Shuttlexpress-MPD is a Music Player Daemon (MPD) client that uses a
Contour ShuttleXpress to control the status of the playback of an MPD
instance.

The program is written to run with Linux. 

Production web page for the Contour Shuttle products:
https://www.contourdesign.com/product/shuttle/

Web page for Music Player Daemon (MPD):
https://www.musicpd.org

The Contour ShuttleXpress is the small device in the Contour Shuttle products.
It is a USB device that has five buttons, dial, and a rotation ring.


Why Was This Program Created
----------------------------
I wanted to use my Griffin Powermate MPD client, Powermate-MPD, on a second
Linux system. The Griffin Powermate is no longer being produced. I need to find
a replacement for the Powermate. The ShuttleXpress is what I found as
substitute for the Powermate.

Actions Taken for ShuttleXpress Inputs Events
---------------------------------------------  
- When a button is pushed:
  -- Button 0: Send the Previous command to MPD.  Move backwards in the MPD
               play list. 
  -- Button 1: Send the Play command to MPD.
  -- Button 2: Send the Pause command to MPD.
  -- Button 3: Send the Stop command to MPD.
  -- Button 4: Send the Next command to MPD. Move forward in the MPD play list. 

  The numbering of the buttons is from left to right.

            2
           1 3 
          0   4

          Pause
      Play     Stop
  Prev             Next

- When the dial is rotated the MPD volume is changed:
  -- Rotated Right: The audio volume is increased. 
  -- Rotated Left:  The audio volume is decreased.

- When the ring is rotated random playback is enabled or disabled.
  -- Rotated Right: Random is enabled.
  -- Rotated Left:  Random is disabled.

Program Options and Defaults
----------------------------
Program Options and Defaults
----------------------------
-d Debug
	Does not demonize and displays message.
-h MPD Host IP Address
	The default host address is ::1.
        ::1 is the IPv6 local host loop-back address
-p MPD Host Service Port
	The MPD host service port is 6600.
-P MPD Polling Interval (Seconds)
        Default and Minimum is 10 seconds.
-s Connect to MPD via MPD's default socket.
        Only works when shuttlexpress-mpd and MPD
          are running on the same system.
        Note: MPD's default Unix socket path is
          a MPD compile time option.
--help 
	Display the program usage details

Required Libraries
------------------
Core C library
MPD C Client 
 - libmpdclient 
   -- https://www.musicpd.org/libs/libmpdclient