= mpeg: interface to the mpeg device driver     include "draw.m";    include "mpeg.m";    mpeg:= load Mpeg Mpeg->PATH;     play:     fn(d:       ref Display,                   w:       ref Image,                   dopaint: int,                   r:       Rect,                   file:    string,                   notify:  chan of string): string;    ctl:      fn(msg: string): int;    keycolor: fn(d: ref Display): ref Image;    Mpeg provides a primitive interface to the mpeg(3) device. Play plays the specified MPEG file in rectangle r within win‐dow w on display d.   The  dopaint  flag  specifies  whether,before  playing  the  movie,  to paint the rectangle with thechroma key colour of the device. Notify is a channel upon which to receive errors and  status.If  notify  is  nil,  play  runs synchronously, returning theempty string ("") when the movie completes, or a  descriptionof any error.  If notify is not nil, play spawns an asynchro‐nous process to play the movie and returns the  empty  stringimmediately;  the  process  returns  the status on the notifychannel when the movie completes. Ctl writes msg, the string given as an argument, to the  MPEGcontrol interface /dev/mpegctl. Keycolor  uses the Display d to create a single-pixel, repli‐cated off screen Image of colour Chroma (16r05). == files/dev/mpeg/dev/mpegctl == source/appl/lib/mpeg.b