macOS Play Alert Sound
│ English (en) │
This article applies to macOS only.
See also: Multiplatform Programming Guide
The Apple macOS operating system has many possible alert sounds which you can play to alert your user to various situation that need their attention. You can use System Sound Services to play short (30 seconds or shorter) sounds. The interface does not provide level, positioning, looping, or timing control, and does not support simultaneous playback: You can play only one sound at a time.
The example application code below shows how to play those alert sounds. In this example the alert sound is being played by choosing a menu item which is just for the purposes of the demonstration.
Note that the choice of 2 for the alert sound to play in this example is purely arbitrary. You should choose the number for the appropriate sound you want to play. Sound number 4096 is particularly interesting for deaf users. Try it :-)
unit unit1;
{$mode objfpc}{$H+}
{$linkframework AudioToolbox}
interface
uses
Forms,
Menus;
type
{ TForm1 }
TForm1 = class(TForm)
MainMenu1: TMainMenu;
MenuItem1: TMenuItem;
procedure MenuItemPlaySoundClick(Sender: TObject);
private
public
end;
var
Form1: TForm1;
implementation
{$R *.lfm}
{ TForm1 }
// Sound procedure declaration
Procedure AudioServicesPlayAlertSound (inSystemSoundID: UInt32)
external name '_AudioServicesPlayAlertSound';
// Menu item OnClick Event
procedure TForm1.MenuItemPlaySoundClick(Sender: TObject);
begin
AudioServicesPlayAlertSound(2); // Use the appropriate value for the sound you want
end;
end.
Playing a sound from a file
Not only can you play the existing operating system alert sounds, you can also play your own .wav sound files. The example application below demonstrates this. The Button1 OnClick event handler plays your sound from the specified file and updates the button caption with the number assigned to the sound.
unit Unit1;
{$mode objfpc}{$H+}
{$linkframework AudioToolbox}
interface
uses
Classes,
SysUtils,
Forms,
Controls,
StdCtrls,
Dialogs,
MacOSAll;
type
TSystemSoundID = UInt32;
pSystemSoundID = ^TSystemSoundID;
{ TForm1 }
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
public
end;
var
Form1: TForm1;
implementation
{$R *.lfm}
{ TForm1 }
// Sound procedure and function declarations
procedure AudioServicesPlayAlertSound (inSystemSoundID: TSystemSoundID); external name '_AudioServicesPlayAlertSound';
function AudioServicesCreateSystemSoundID(inFileURL: CFURLRef; outSystemSoundID: pSystemSoundID):OSStatus; external name '_AudioServicesCreateSystemSoundID';
procedure TForm1.Button1Click(Sender: TObject);
var
newSoundID:TSystemSoundID;
filePathURL: CFURLRef;
filePathCFStringRef: CFStringRef;
filePathStr: String;
status: Integer = -1;
begin
// Play sound from file
filePathStr := '/usr/local/share/fpcsrc/fpc-3.0.4/packages/libndsfpc/examples/audio/maxmod/basic_sound/audio/Ambulance.wav';
filePathCFStringRef := CFStringCreateWithPascalString(kCFAllocatorDefault, filePathStr, CFStringGetSystemEncoding);
filePathURL := CFURLCreateWithFileSystemPath(kCFAllocatorDefault, filePathCFStringRef, kCFURLPOSIXPathStyle, false);
status := AudioServicesCreateSystemSoundID(filePathURL, @newSoundID);
if(status = kAudioServicesNoError) then
begin
Button1.Caption := IntToStr(newSoundID);
AudioServicesPlayAlertSound(newSoundID);
end
else
ShowMessage('Error in AudioServicesCreateSystemSoundID()');
end;
end.
