music_playfile

#Music.PlayFile

##Syntax Music.PlayFile ( fileName : string )

##Description The Music.PlayFile procedure is used to play a file of music. The file must be in one of the acceptable formats and the machine, must have the appropriate hardware.

The fileName parameter must give the format of the file:

WAV files "WAV:filename" or "filename.WAV" MP3 files "MP3:filename" or "filename.MP3" MIDI files "MIDI:filename" or "filename.MIDI"

Sounds are produced synchronously on a per process basis. This means that when a process executes a Music.Sound, Music.Play or Music.PlayFile command, it stops until the command is finished. However, other processes will continue executing.

##Details To play music while performing any other activity, the call to Music.PlayFile must be executed in its own process. The process is then called using the fork command. When a fork command is given, execution starts on the process (like a procedure call) and continues following the fork command at the same time.

##Example This program plays the music in the file "branden3.wav" while drawing ovals on the screen.

    process DoMusic
        loop
            Music.PlayFile ("branden3.wav")
        end loop
    end DoMusic
    
    fork DoMusic
    var x, y, clr : int
    loop
        x := Rand.Int (0, maxx)
        y := Rand.Int (0, maxy)
        clr := Rand.Int (0, maxcolor)
        Draw.FillOval (x, y, 30, 30, clr)
    end loop

##Details To play a sound file requires that the computer be equipped with a sound card and speakers.

##Details The Turing 4.1 software can play files in the following audio formats: WAVE (.wav) files, MIDI files (.midi or .mid), and MP3 files (.mp3). In general, MIDI files are the most efficient and thus are the preferred form for longer music pieces like background music. WAVE files can record anything, not just music, so are often used for sound effects.

##Details The Turing 4.1 software can also play music on a compact disk. To play the complete contents of the compact disk, the filename is �cd�. To play a single track from a compact disk, the filename is �cd:[track number]�.

    Music.PlayFile ("cd")       % Play the entire CD
    Music.PlayFile ("cd:3")     % Play the third track on the CD

##Details On the PC, different formats of music can play simultaneously. This means that a program might use a MIDI file as a background soundtrack and then use WAVE files for individual sound effects. The sound effects would not interfere with the background music. Playing a second music file with the same format as an already playing piece immediately halts the first piece and starts the second. This can be used to stop a single type of music by playing a short silent piece of music.

##Example This program bounces a maple leaf around the screen with background music and a sound effect when the maple leaf hits an edge. When the user presses any key, the program immediately exits.

    const STAR_SIZE : int := 80
    var pic, x, y, dx, dy : int
    var finished : boolean := false
    
    % Play sound effect once.
    process Boing
        Music.PlayFile ("boing.wav")
    end Boing
    
    % Loop playing background music until 'finished' is true.
    process BackgroundMusic
        loop
            exit when finished
            Music.PlayFile ("background.mid")
        end loop
    end BackgroundMusic
    
    % Get the original picture
    Draw.FillStar (3, 3, STAR_SIZE - 3, STAR_SIZE - 3, brightred)
    pic := Pic.New (0, 0, STAR_SIZE, STAR_SIZE)
    cls
    
    % Set the initial location and direction of movement
    x := Rand.Int (0, maxx - STAR_SIZE)
    y := Rand.Int (0, maxy - STAR_SIZE)
    dx := 1
    dy := 1
    
    fork BackgroundMusic    % Start background music playing
    
    loop
        if x + dx < 0 or x + dx > maxx - STAR_SIZE then
            dx := -dx
            fork Boing
        end if
        if y + dy < 0 or y + dy > maxy - STAR_SIZE then
            dy := -dy
            fork Boing
        end if
        x += dx
        y += dy
        Pic.Draw (pic, x, y, picCopy)
        exit when hasch
        Time.Delay (5)
    end loop
    
    % Stop the background music.
    finished := true
    Music.PlayFileStop

##See also music_playfilestop.html to halt a music file that is current playing, music_playfilereturn.html fora procedure that starts a music file playing and returns immediately(meaning that you do not need to use process and forkstatements), and **music_playfileloop.html**that starts a music file playing continuously until it is stopped without the use of process or fork.

##Status Exported qualified.

This means that you can only call the function by calling Music.PlayFile, not by calling PlayFile.