Juke_Box custom server communication with pl_elem and pl_seg

When your state table asks the Juke_Box custom server to start playing a tune, the Juke_Box custom server starts a process to play the tune to the music channel until it is told to stop.

The program, or music player, uses the following input parameters:

argv[0] player_program_name
The name used to invoke the music player, for example, pl_elem.
argv[1] pack_number
An ASCII string containing the decimal representation of a number; the number of the pack where the tune is to be played. This string is passed to CA_Open_Music_Channel in the vpack field.
argv[2] music_title
An ASCII string giving the music title to the music player. The music player passes this string to the CA_Open_Music_Channel call in the music_title field.
argv[3] parameter_string
An ASCII character string specified either in the Juke_Box custom server configuration file, or passed by the state table when a music title is added using juke_box_configure_music. This string contains the information the music player needs to find and access the tune known as music_title.