= 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 the
chroma key colour of the device.

Notify is a channel upon which to receive errors and  status.
If  notify  is  nil,  play  runs synchronously, returning the
empty string ("") when the movie completes, or a  description
of any error.  If notify is not nil, play spawns an asynchro‐
nous process to play the movie and returns the  empty  string
immediately;  the  process  returns  the status on the notify
channel when the movie completes.

Ctl writes msg, the string given as an argument, to the  MPEG
control 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