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.

示例:

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.