//枚举函数
function DirectSoundEnumerate(
  lpDSEnumCallback: TDSEnumCallback; //回调函数
  lpContext: Pointer                 //用户指针
): HResult; stdcall; //返回错误代码, 成功则返回 DS_OK(0)

//DirectSoundEnumerate 需要的回调函数的原形:
TDSEnumCallback = function(
  lpGuid: PGUID;            //设备的 GUID
  lpcstrDescription: PChar; //设备描述
  lpcstrModule: PChar;      //模块标识
  lpContext: Pointer        //由 DirectSoundEnumerate 提供的用户指针
): BOOL; stdcall; //返回 True 表示要继续枚举, 不在继续找了就返回 False

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    ListBox1: TListBox; //只在窗体上放了一个列表框
    procedure FormCreate(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses DirectSound; //!

function EnumCallback(lpGuid: PGUID; lpcstrDescription, lpcstrModule: PChar;
    lpContext: Pointer): BOOL; stdcall;
begin
  Form1.ListBox1.Items.Add(lpcstrDescription);
  Result := True;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  DirectSoundEnumerate(EnumCallback, nil);
end;

end.

uses DirectSound;

function EnumCallback(lpGuid: PGUID; lpcstrDescription, lpcstrModule: PChar;
    lpContext: Pointer): BOOL; stdcall;
begin
  TStrings(lpContext).Add(lpcstrDescription);
  Result := True;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  DirectSoundEnumerate(EnumCallback, ListBox1.Items);
end;

uses DirectSound;

function EnumCallback(lpGuid: PGUID; lpcstrDescription, lpcstrModule: PChar;
    lpContext: Pointer): BOOL; stdcall;
begin
  if lpGuid <> nil then TStrings(lpContext).Add(GUIDToString(lpGuid^));
  TStrings(lpContext).Add(lpcstrDescription);
  if lpcstrModule <> nil then TStrings(lpContext).Add(lpcstrModule);
  TStrings(lpContext).Add(EmptyStr);
  Result := True;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  DirectSoundEnumerate(EnumCallback, ListBox1.Items);
end;