macOS NSSound

This article applies to macOS only.

NSSound Encoding and file format support

NSSound supports any audio encodings and file formats that QuickTime does (as it still uses QuickTime for certain things) and, as of macOS 10.3 (Panther), it also uses CoreAudio for playback. The NSSound initializer first tries to use CoreAudio with the file it is initialized with. If that fails, NSSound tries to use QuickTime. If that fails, NSSound initialization will fail.

NSSound will use CoreAudio for any files supported by the CoreAudio AudioFile APIs as long as the file type is supported in <AudioToolbox/AudioFile.h> and the encoding format has codec support (with the exception of Linear PCM which is always supported). The table below shows CoreAudio support.

Sound File Format	Sound Data Formats
AAC (.aac, .adts)	'aac '
AC3 (.ac3)	'ac-3'
AIFC (.aif, .aiff,.aifc)	BEI8, BEI16, BEI24, BEI32, BEF32, BEF64, 'ulaw', 'alaw', 'MAC3', 'MAC6', 'ima4' , 'QDMC', 'QDM2', 'Qclp', 'agsm'
AIFF (.aiff)	BEI8, BEI16, BEI24, BEI32
Apple Core Audio Format (.caf)	'.mp3', 'MAC3', 'MAC6', 'QDM2', 'QDMC', 'Qclp', 'Qclq', 'aac ', 'agsm', 'alac', 'alaw', 'drms', 'dvi ', 'ima4', 'lpc ', BEI8, BEI16, BEI24, BEI32, BEF32, BEF64, LEI16, LEI24, LEI32, LEF32, LEF64, 'ms\x00\x02', 'ms\x00\x11', 'ms\x001', 'ms\x00U', 'ms \x00', 'samr', 'ulaw'
MPEG Layer 3 (.mp3)	'.mp3'
MPEG 4 Audio (.mp4)	'aac '
MPEG 4 Audio (.m4a)	'aac ', alac'
NeXT/Sun Audio (.snd, .au)	BEI8, BEI16, BEI24, BEI32, BEF32, BEF64, 'ulaw'
Sound Designer II (.sd2)	BEI8, BEI16, BEI24, BEI32
WAVE (.wav)	LEUI8, LEI16, LEI24, LEI32, LEF32, LEF64, 'ulaw', 'alaw'

  Note: Apple ceased support for QuickTime on macOS in 2018 at which time the underlying media framework for QuickTime and QTKit was deprecated in favour of a newer graphics framework, AVFoundation. QuickTime's underlying media framework was completely removed from macOS 10.15 (Catalina).

QuickTime supports the following audio file and data formats:

A-law
Advanced Audio Coding (AAC)
AMR Narrowband
Apple Lossless
Au file format
Audio Interchange File Format (AIFF)
Apple Core Audio Format (CAF)
FLAC (since macOS 10.13)
MACE
Microsoft Adaptive DPCM (MS ADPCM)
MIDI
MPEG-1 Audio Layer 3 (MP3)
Pulse-code modulation (PCM)
QCELP (Qualcomm PureVoice)
QDesign
Waveform Audio File Format (WAV)
μ-law

Playing system sounds

Here is the list of macOS system sounds (found in /System/Library/Sounds): Basso, Blow, Bottle, Frog, Funk, Glass, Hero, Morse, Ping, Pop, Purr, Sosumi, Submarine, and Tink.

A system sound can be played very easily using the NSSound class. The process is very simple:

Create an object based on the NSSound class;
Load an audio file into the NSSound object using the SoundNamed class method;
Play the audio file using the Play class method.

Here is the code to do that:

unit Unit1;

{$mode objfpc}{$H+}
{$modeswitch objectivec1}

interface

uses
  Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, CocoaAll, CocoaUtils;   

...

Var
  Form1: TForm1;
  mySound: NSSound := Nil;                              // Create an object based on the NSSound class

...

procedure TForm1.PlayButtonClick(Sender: TObject);
var
  status: boolean = false;
begin
  mySound := NSSound.soundNamed(NSStringUTF8('Frog'));  // Load an audio file into the NSSound object 
  mySound.play;                                         // Play the audio file

  if(not status) then                                   // Play returns true/false for success/failure
    ShowMessage('Error!'); 
end;

...

end.

While the Frog system sound file is named Frog.aiff, you can drop the file extension (.aiff) from the filename as we did in the above example code.

You can also combine the loading of a sound and playing it and omit the creation of a sound object:

NSSound.soundNamed(NSStringUTF8('Frog')).play;          // Load and play audio file

Playing sounds from your application bundle

The soundNamed class method searches your application’s main bundle and if no sound file can be located in the application main bundle, the following directories are searched in order:

~/Library/Sounds
/Library/Sounds
/Network/Library/Sounds
/System/Library/Sounds

If no data file can be found for the sound name, no object is created and nil is returned.

Copy the sound file from /Applications/iPhoto.app/Contents/Resources/Music/Minuet in G.mp3 to the Resources sub-directory of your application bundle. You can now play that sound file using the code below:

unit Unit1;

{$mode objfpc}{$H+}
{$modeswitch objectivec1}

interface

uses
  Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, CocoaAll, CocoaUtils;   

...

Var
  Form1: TForm1;
  mySound: NSSound := Nil;                                     // Create an object based on the NSSound class

...

procedure TForm1.PlayButtonClick(Sender: TObject);
var
  status: boolean = false;
begin
  mySound := NSSound.soundNamed(NSStringUTF8('Minuet in G'));  // Load an audio file into the NSSound object 
  mySound.play;                                                // Play the audio file 

  if(not status) then                                          // Play returns true/false for success/failure
    ShowMessage('Error!'); 
end;

...

end.

Note that once again the file extension is not used when loading sound files using the soundNamed class method. Also note that AIFF files must use the .aiff file extension (not .aif) for it to be located by the soundNamed class method.

Playing sounds from elsewhere

If you want to load audio files from somewhere else in the file system other than from the system sounds directory or your application bundle, you can use the NSSound class method initWithContentsOfFile_byReference. As you would expect, this method attempts to initialize a newly allocated NSSound instance with the audio data in the specified file. The following code example shows you how to create an NSSound instance and initialize it with a sound file using a pathname to the file.

unit Unit1;

{$mode objfpc}{$H+}
{$modeswitch objectivec1}

interface
uses
  Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, CocoaAll, CocoaUtils;   

...

Var
  Form1: TForm1;
  mySound: NSSound = Nil;                                                           // Create an object based on the NSSound class

...

procedure TForm1.PlayButtonClick(Sender: TObject);
var
  audioFilePath: NSString;
  status: boolean = false;
begin
  audioFilePath := NSStringUTF8('/Applications/iPhoto.app/Contents/Resources/Music/Barbeque Blues.m4a');
  // mySound := NSSound.alloc;
  // mySound := mySound.initWithContentsOfFile_byReference(audioFilePath, True);
  // The two lines above can be combined into the single line below
  mySound := NSSound.alloc.initWithContentsOfFile_byReference(audioFilePath, True);  // Load an audio file into the NSSound object
  mySound.Play;                                                                      // Play the audio file

  if(not status) then                                                                // Play returns true/false for success/failure
    ShowMessage('Error!'); 
end;                        

...

end.

As we used NSSound.alloc... in the code above, do not forget to use mySound.Release; mySound :- Nil; mySound.dealloc somewhere appropriate or you'll create a memory leak every time you play the file. This is not necessary when using NSSound.soundNamed(soundName) class method in the previous two examples because that method creates an NSSound object for you using a helper function or, as the Apple documentation states more opaquely the "NSSound instance is initialized with the sound data identified by soundName".

Managing sound playback

This section describes how to manage the playback of a sound using the NSSound class.

Pause

procedure TForm1.PauseButtonClick(Sender: TObject);
begin
  mySound.pause;
end;

Resume

procedure TForm1.ResumeButtonClick(Sender: TObject);
begin
  mySound.resume;
end;

Stop

procedure TForm1.StopButtonClick(Sender: TObject);
begin
  mySound.Stop;
end;

Volume control

mySound.SetVolume(0.5);

The valid range is between 0.0 and 1.0. The value of this property does not affect the systemwide volume. Make sure you set it after loading and before playing the sound file. macOS 10.5+ required.

Loop control

When the value of the loops instance property is True, the sound restarts playback when it finishes and does not send didFinishPlaying message to its delegate when it reaches the end of its content and restarts playback. The default value of this property is False. macOS 10.5+ required.

mySound.setLoops(True);   // Set true and the sound will continue looping

Sound duration

The duration instance property provides the duration of the sound in seconds. macOS 10.5+ required.

status := mySound.play;

if(status) then
  ShowMessage('Duration: ' + FloatToStrF(mySound.duration, ffFixed, 0, 2) + ' seconds')
else
  ShowMessage('Not OK');

Sound progress

The currentTime instance property returns the sound’s playback progress in seconds. A sounds starts with currentTime equal to zero and ends with currentTime equal to sound duration minus one. macOS 10.5+ required.

procedure TForm1.PauseButtonClick(Sender: TObject);
begin
  mySound.pause;

  ShowMessage('Progress: ' + FloatToStrF(mySound.currentTime, ffFixed, 0, 2)
    + ' of ' + FloatToStrF(mySound.duration, ffFixed, 0, 2) + ' seconds');
end;

Determine if sound is playing

if(mySound.IsPlaying) then
  ShowMessage('Sound is playing')
else   
  ShowMessage('Sound is not playing');

Determine when sound finishes playing

This is somewhat more complicated. First, create a delegate object:

Uses 
  ...

type

  { NSSoundFinishedDelegate }
  SoundFinishedDelegate = objcclass(NSObject, NSSoundDelegateProtocol)
  public
    procedure sound_didFinishPlaying(Sound: NSSound; FinishedPlaying: Boolean);
       message 'sound:didFinishPlaying:';
  end;

Add two new variables: SoundDelegate for the SoundFinishedDelegate and a Playing boolean variable to indicate whether a sound is playing.

Var
  Form1: TForm1;
  mySound: NSSound = Nil;                              // Create an object based on the NSSound class
  SoundDelegate : SoundFinishedDelegate;
  SoundPlaying : Boolean = False;

Now create the new delegate procedure:

{ NSSoundFinishedDelegate }
procedure SoundFinishedDelegate.sound_didFinishPlaying(Sound: NSSound; FinishedPlaying: Boolean);
begin
  if(FinishedPlaying) then
     begin
       SoundPlaying := False;

       Form1.PlayButton.Enabled   := True;
       Form1.PauseButton.Enabled  := False;
       Form1.ResumeButton.Enabled := False;
       Form1.StopButton.Enabled   := False;
       
       Sound.Release;  // avoid memory
       Sound := Nil;   // leak when using
       Sound.dealloc;  // NSSound.alloc...
     end;
end;

The updated play procedure:

 
procedure TForm1.PlayButtonClick(Sender: TObject);
var
  status: Boolean;
begin
  Sound := NSSound.alloc.initWithContentsOfFile_byReference(NSStringUTF8
    ('/Applications/iPhoto.app/Contents/Resources/Music/Barbeque Blues.m4a'), True); // File system sound file
  //Sound := NSSound.SoundNamed(NSStringUTF8('Minuet in G'));                        // Bundle sound file
  //Sound := NSSound.soundNamed(NSStringUTF8('Frog'));                               // System sound file

  Sound.setDelegate(SoundDelegate);

  status := Sound.play;
  if(status) then
    SoundPlaying := True
  else
    ShowMessage('Playing failed!');

  PlayButton.Enabled  := False;
  PauseButton.Enabled := True;
  StopButton.Enabled  := True;
end;

Finally, the new Initialisation clause for the delegate object:

  
Initialization
  SoundDelegate := SoundFinishedDelegate.alloc.init;
End.

Here is the whole unit for the application which now takes care of the enabled-state of the Play/Pause/Resume/Stop buttons:

  
unit Unit1;

{$mode objfpc}{$H+}
{$modeswitch objectivec1}

interface

uses
  Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, CocoaAll,
  CocoaUtils;

type

  { NSSoundFinishedDelegate }
  SoundFinishedDelegate = objcclass(NSObject, NSSoundDelegateProtocol)
  public
    procedure sound_didFinishPlaying(Sound: NSSound; FinishedPlaying: Boolean);
       message 'sound:didFinishPlaying:';
  end;

  { TForm1 }
  TForm1 = class(TForm)
    StopButton: TButton;
    PlayButton: TButton;
    PauseButton: TButton;
    ResumeButton: TButton;
    procedure StopButtonClick(Sender: TObject);
    procedure FormShow(Sender: TObject);
    procedure PlayButtonClick(Sender: TObject);
    procedure PauseButtonClick(Sender: TObject);
    procedure ResumeButtonClick(Sender: TObject);
  private
  public
end;

var
  Form1: TForm1;
  Sound: NSSound = Nil;
  SoundDelegate : SoundFinishedDelegate;
  SoundPlaying : Boolean = False;

implementation

{$R *.lfm}

{ NSSoundFinishedDelegate }

procedure SoundFinishedDelegate.sound_didFinishPlaying(Sound: NSSound; FinishedPlaying: Boolean);
begin
  if(FinishedPlaying) then
     begin
       SoundPlaying := False;

       Form1.PlayButton.Enabled   := True;
       Form1.PauseButton.Enabled  := False;
       Form1.ResumeButton.Enabled := False;
       Form1.StopButton.Enabled   := False;

       Sound.Release;  // avoid memory
       Sound := Nil;   // leak when using
       Sound.dealloc;  // NSSound.alloc...
     end;
end;

{ TForm1 }

// Setup button state
procedure TForm1.FormShow(Sender: TObject);
begin
  PauseButton.Enabled  := False;
  ResumeButton.Enabled := False;
  StopButton.Enabled   := False;
end;

// Play
procedure TForm1.PlayButtonClick(Sender: TObject);
var
  status: Boolean;
begin
  Sound := NSSound.alloc.initWithContentsOfFile_byReference(NSStringUTF8
    ('/Applications/iPhoto.app/Contents/Resources/Music/Barbeque Blues.m4a'), True); // File system sound example
  //Sound := NSSound.SoundNamed(NSStringUTF8('Minuet in G'));                        // Bundle sound file
  //Sound := NSSound.soundNamed(NSStringUTF8('Frog'));                               // System file

  Sound.setDelegate(SoundDelegate);

  status := Sound.play;
  if(status) then
    SoundPlaying := True
  else
    ShowMessage('Playing failed!');

  PlayButton.Enabled  := False;
  PauseButton.Enabled := True;
  StopButton.Enabled  := True;
end;

// Pause
procedure TForm1.PauseButtonClick(Sender: TObject);
begin
  if(SoundPlaying) then
    begin
      Sound.pause;
      PauseButton.Enabled  := False;
      StopButton.Enabled   := False;
      ResumeButton.Enabled := True;
    end;
end;

// Resume
procedure TForm1.ResumeButtonClick(Sender: TObject);
begin
  if(SoundPlaying) then
    begin
      Sound.resume;
      ResumeButton.Enabled := False;
      PauseButton.Enabled  := True;
      StopButton.Enabled   := True;
    end;
end;

// Stop
procedure TForm1.StopButtonClick(Sender: TObject);
begin
  if(SoundPlaying) then
     begin
      SoundPlaying := False;
      Sound.stop;

      Sound.Release;  // avoid memory
      Sound := Nil;   // leak when using
      Sound.dealloc;  // NSSound.alloc...

      PlayButton.Enabled   := True;
      PauseButton.Enabled  := False;
      ResumeButton.Enabled := False;
      StopButton.Enabled   := False;
     end;
end;

Initialization
  SoundDelegate := SoundFinishedDelegate.alloc.init;
end.

External links

macOS NSSound

Contents

NSSound Encoding and file format support

Playing system sounds

Playing sounds from your application bundle

Playing sounds from elsewhere

Managing sound playback

Pause

Resume

Stop

Volume control

Loop control

Sound duration

Sound progress

Determine if sound is playing

Determine when sound finishes playing

See also

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