在 Delphi 下使用 DirectSound (8): IDirectSound8.DuplicateSoundBuffer() 与 IDirectSoundBuffer.GetStatus()

IDirectSoundBuffer.GetStatus() 用于获取缓冲区的当前状态, 譬如是否正在播放、是否指定为循环播放等等.

IDirectSound8.DuplicateSoundBuffer() 是通过根据已存在的缓冲区建立缓冲区副本, 这类似引用; 通过它可以让同一个声音交叉播放.
复制缓冲区不能复制主缓冲区.

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示例:

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unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;     //播放 buf
    Button2: TButton;     //播放 bufs[0]
    Button3: TButton;     //播放 bufs[1]
    Button4: TButton;     //全部停止
    CheckBox1: TCheckBox; //控制是否循环播放
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
    procedure CheckBox1Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses DirectSound, MMSystem, ReadWave; //ReadWave 是前面(7)自定义的单元

var
  myDSound: IDirectSound8;
  buf: IDirectSoundBuffer; //准备用这个缓冲区载入波形
  bufs: array[0..1] of IDirectSoundBuffer; //这个缓冲区数组都将复制上面的 buf
  loop: DWORD = 0; //是否循环播放; 0：不循环; 1(DSBPLAY_LOOPING)：循环

{判断缓冲区是否正在播放的函数}
function IsPlay(b: IDirectSoundBuffer): Boolean;
var
  dStatus: DWORD;
begin
  Result := b <> nil;
  if Succeeded(b.GetStatus(dStatus)) then
    Result := dStatus and DSBSTATUS_PLAYING = DSBSTATUS_PLAYING;
end;

{初始化设备}
procedure TForm1.FormCreate(Sender: TObject);
var
  wavFormat: TWaveFormatEx;
  bufDesc: TDSBufferDesc;
  wavPath: string;
  wav: TReadWave;
  p1: Pointer;
  n1: DWORD;
  i: Integer;
begin
  with TOpenDialog.Create(nil) do begin
    Filter := 'Wave File(*.wav)|*.wav';
    if Execute then wavPath := FileName;
    Free;
  end;

  wav := TReadWave.Create;
  if not wav.Open(wavPath) then
  begin
    ShowMessage('打开失败');
    wav.Free;
    Application.Terminate;
  end;

  DirectSoundCreate8(nil, myDSound, nil);
  myDSound.SetCooperativeLevel(Handle, DSSCL_NORMAL);

  ZeroMemory(@bufDesc, SizeOf(TDSBufferDesc));
  bufDesc.dwSize := SizeOf(TDSBufferDesc);
  bufDesc.dwFlags := DSBCAPS_STATIC;
  bufDesc.dwBufferBytes := wav.Size;
  bufDesc.lpwfxFormat := @wav.Format;

  {建立 buf 并载入波形}
  myDSound.CreateSoundBuffer(bufDesc, buf, nil);
  buf.Lock(0, 0, @p1, @n1, nil, nil, DSBLOCK_ENTIREBUFFER);
  wav.Read(p1, n1);
  wav.Free;
  buf.Unlock(p1, n1, nil, 0);

  {根据 buf 复制几个缓冲区}
  for i := Low(bufs) to High(bufs) do
  begin
    myDSound.DuplicateSoundBuffer(buf, bufs[i]);
  end;
end;

{播放或暂停 buf}
procedure TForm1.Button1Click(Sender: TObject);
begin
  if IsPlay(buf) then buf.Stop else buf.Play(0, 0, loop);
end;

{播放或暂停 buf[0]}
procedure TForm1.Button2Click(Sender: TObject);
begin
  if IsPlay(bufs[0]) then buf.Stop else bufs[0].Play(0, 0, loop);
end;

{播放或暂停 buf[1]}
procedure TForm1.Button3Click(Sender: TObject);
begin
  if IsPlay(bufs[1]) then buf.Stop else bufs[1].Play(0, 0, loop);
end;

{全部停止}
procedure TForm1.Button4Click(Sender: TObject);
var
  i: Integer;
begin
  if buf <> nil then buf.Stop;
  for i := Low(bufs) to High(bufs) do if bufs[i] <> nil then bufs[i].Stop;
end;

{切换是否循环播放, 没有对正在播放的缓冲区进行控制}
procedure TForm1.CheckBox1Click(Sender: TObject);
begin
  loop := DWORD(CheckBox1.Checked);
end;

procedure TForm1.FormDestroy(Sender: TObject);
var
  i: Integer;
begin
  buf := nil;
  for i := Low(bufs) to High(bufs) do bufs[i] := nil;
  myDSound := nil;
end;

end.

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