使用 DirectSound 前应先建立 IDirectSound8 对象(之前的版本是 IDirectSound):

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function DirectSoundCreate8(pcGuidDevice: PGUID;      //设备的 GUID; 指定 nil 表示使用默认声卡out ppDS8: IDirectSound8; //要返回的 IDirectSound8 对象pUnkOuter: IUnknown       //未使用, 应为 nil
): HResult; stdcall; //返回错误码//也可使用 GUID 常数指定设备:
DSDEVID_DefaultPlayback      //默认设备
DSDEVID_DefaultVoicePlayback //二级默认设备

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然后通过 IDirectSound8 对象(它代表着一个播放设备)创建缓冲区, 以写入声音信息.

这里的缓冲区分 "主缓冲区" 和 "次缓冲区". 主缓冲区只有一个; 次缓冲区可以有多个, 以实现多个声音的同时播放.

DirectSound 会尽量使用硬件(声卡)提供的缓冲区; 如果硬件不支持则只好使用系统内存做缓冲区, 但这样效率不及前者.

通过 IDirectSound8.GetCaps() 方法可以获取指定设备的详细性能:

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function GetCaps(out pDSCaps: TDSCaps //获取到的信息将放在 TDSCaps 结构体中
): HResult; stdcall;//TDSCaps 结构:
TDSCaps = packed recorddwSize                         : DWORD; //结构大小(字节)dwFlags                        : DWORD; //性能标志dwMinSecondarySampleRate       : DWORD; //次缓冲区的最小取样率dwMaxSecondarySampleRate       : DWORD; //次缓冲区的最大取样率dwPrimaryBuffers               : DWORD; //主缓冲区个数dwMaxHwMixingAllBuffers        : DWORD; //硬件缓冲区的最大数目dwMaxHwMixingStaticBuffers     : DWORD; //静态硬件缓冲区的最大数目dwMaxHwMixingStreamingBuffers  : DWORD; //流式硬件缓冲区的最大数目dwFreeHwMixingAllBuffers       : DWORD; //空闲的硬件缓冲区个数dwFreeHwMixingStaticBuffers    : DWORD; //空闲的静态硬件缓冲区个数dwFreeHwMixingStreamingBuffers : DWORD; //空闲的流式硬件缓冲区个数dwMaxHw3DAllBuffers            : DWORD; //3D 硬件缓冲区的最大数目dwMaxHw3DStaticBuffers         : DWORD; //3D 静态硬件缓冲区的最大数目dwMaxHw3DStreamingBuffers      : DWORD; //3D 流式硬件缓冲区的最大数目dwFreeHw3DAllBuffers           : DWORD; //空闲的 3D 硬件缓冲区的最大数目dwFreeHw3DStaticBuffers        : DWORD; //空闲的 3D 静态硬件缓冲区的最大数目dwFreeHw3DStreamingBuffers     : DWORD; //空闲的 3D 流式硬件缓冲区的最大数目dwTotalHwMemBytes              : DWORD; //硬件内存总量(字节)dwFreeHwMemBytes               : DWORD; //空闲的硬件内存总量(字节)dwMaxContigFreeHwMemBytes      : DWORD; //空闲的硬件内存最大连续块大小(字节)dwUnlockTransferRateHwBuffers  : DWORD; //硬件缓冲区的数据传输速率(千字节/秒)dwPlayCpuOverheadSwBuffers     : DWORD; //混合软件缓冲区占用的 CPU 周期的百分比dwReserved1                    : DWORD; //未使用dwReserved2                    : DWORD; //未使用
end;

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查看默认设备性能的测试程序:

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unit Unit1;interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, StdCtrls;typeTForm1 = class(TForm)Memo1: TMemo; //用于显示信息procedure FormCreate(Sender: TObject);end;varForm1: TForm1;implementation{$R *.dfm}uses DirectSound;procedure TForm1.FormCreate(Sender: TObject);
varmyDSound: IDirectSound8;capInfo: TDSCaps;p: PDSCaps;
beginMemo1.ScrollBars := ssBoth;Memo1.Align := alLeft;Memo1.Clear;FillChar(capInfo, SizeOf(TDSCaps), 0);capInfo.dwSize := SizeOf(TDSCaps);DirectSoundCreate8(nil, myDSound, nil);myDSound.GetCaps(capInfo);with Memo1.Lines do beginAdd(Format('%d'#9'dwSize',                         [capInfo.dwSize                        ]));Add(Format('%d'#9'dwFlags',                        [capInfo.dwFlags                       ]));Add(Format('%d'#9'dwMinSecondarySampleRate',       [capInfo.dwMinSecondarySampleRate      ]));Add(Format('%d'#9'dwMaxSecondarySampleRate',       [capInfo.dwMaxSecondarySampleRate      ]));Add(Format('%d'#9'dwPrimaryBuffers',               [capInfo.dwPrimaryBuffers              ]));Add(Format('%d'#9'dwMaxHwMixingAllBuffers',        [capInfo.dwMaxHwMixingAllBuffers       ]));Add(Format('%d'#9'dwMaxHwMixingStaticBuffers',     [capInfo.dwMaxHwMixingStaticBuffers    ]));Add(Format('%d'#9'dwMaxHwMixingStreamingBuffers',  [capInfo.dwMaxHwMixingStreamingBuffers ]));Add(Format('%d'#9'dwFreeHwMixingAllBuffers',       [capInfo.dwFreeHwMixingAllBuffers      ]));Add(Format('%d'#9'dwFreeHwMixingStaticBuffers',    [capInfo.dwFreeHwMixingStaticBuffers   ]));Add(Format('%d'#9'dwFreeHwMixingStreamingBuffers', [capInfo.dwFreeHwMixingStreamingBuffers]));Add(Format('%d'#9'dwMaxHw3DAllBuffers',            [capInfo.dwMaxHw3DAllBuffers           ]));Add(Format('%d'#9'dwMaxHw3DStaticBuffers',         [capInfo.dwMaxHw3DStaticBuffers        ]));Add(Format('%d'#9'dwMaxHw3DStreamingBuffers',      [capInfo.dwMaxHw3DStreamingBuffers     ]));Add(Format('%d'#9'dwFreeHw3DAllBuffers',           [capInfo.dwFreeHw3DAllBuffers          ]));Add(Format('%d'#9'dwFreeHw3DStaticBuffers',        [capInfo.dwFreeHw3DStaticBuffers       ]));Add(Format('%d'#9'dwFreeHw3DStreamingBuffers',     [capInfo.dwFreeHw3DStreamingBuffers    ]));Add(Format('%d'#9'dwTotalHwMemBytes',              [capInfo.dwTotalHwMemBytes             ]));Add(Format('%d'#9'dwFreeHwMemBytes',               [capInfo.dwFreeHwMemBytes              ]));Add(Format('%d'#9'dwMaxContigFreeHwMemBytes',      [capInfo.dwMaxContigFreeHwMemBytes     ]));Add(Format('%d'#9'dwUnlockTransferRateHwBuffers',  [capInfo.dwUnlockTransferRateHwBuffers ]));Add(Format('%d'#9'dwPlayCpuOverheadSwBuffers',     [capInfo.dwPlayCpuOverheadSwBuffers    ]));end;
end;end.

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查看所有设备性能的测试程序:

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unit Unit1;interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, StdCtrls;typeTForm1 = class(TForm)Memo1: TMemo;ComboBox1: TComboBox; //用于设备列表procedure FormCreate(Sender: TObject);procedure ComboBox1Change(Sender: TObject);end;varForm1: TForm1;implementation{$R *.dfm}uses DirectSound;varguidArr: array of TGUID;function EnumCallback(lpGuid: PGUID; lpcstrDescription, lpcstrModule: PChar;lpContext: Pointer): BOOL; stdcall;
beginif lpGuid <> nil thenbeginTStrings(lpContext).Add(lpcstrDescription);SetLength(guidArr, Length(guidArr) + 1);guidArr[Length(guidArr) - 1] := lpGuid^;end;Result := True;
end;procedure TForm1.FormCreate(Sender: TObject);
beginComboBox1.Align := alTop;Memo1.ScrollBars := ssBoth;Memo1.Align := alClient;Memo1.Clear;DirectSoundEnumerate(EnumCallback, ComboBox1.Items);ComboBox1.ItemIndex := 0;ComboBox1.OnChange(nil);
end;procedure TForm1.ComboBox1Change(Sender: TObject);
varmyDSound: IDirectSound8;capInfo: TDSCaps;p: PDSCaps;
beginMemo1.Clear;ZeroMemory(@capInfo, SizeOf(TDSCaps));capInfo.dwSize := SizeOf(TDSCaps);DirectSoundCreate8(@guidArr[ComboBox1.ItemIndex], myDSound, nil);Caption := GUIDToString(guidArr[ComboBox1.ItemIndex]);myDSound.GetCaps(capInfo);with Memo1.Lines do beginAdd(Format('%d'#9'dwSize',                         [capInfo.dwSize                        ]));Add(Format('%d'#9'dwFlags',                        [capInfo.dwFlags                       ]));Add(Format('%d'#9'dwMinSecondarySampleRate',       [capInfo.dwMinSecondarySampleRate      ]));Add(Format('%d'#9'dwMaxSecondarySampleRate',       [capInfo.dwMaxSecondarySampleRate      ]));Add(Format('%d'#9'dwPrimaryBuffers',               [capInfo.dwPrimaryBuffers              ]));Add(Format('%d'#9'dwMaxHwMixingAllBuffers',        [capInfo.dwMaxHwMixingAllBuffers       ]));Add(Format('%d'#9'dwMaxHwMixingStaticBuffers',     [capInfo.dwMaxHwMixingStaticBuffers    ]));Add(Format('%d'#9'dwMaxHwMixingStreamingBuffers',  [capInfo.dwMaxHwMixingStreamingBuffers ]));Add(Format('%d'#9'dwFreeHwMixingAllBuffers',       [capInfo.dwFreeHwMixingAllBuffers      ]));Add(Format('%d'#9'dwFreeHwMixingStaticBuffers',    [capInfo.dwFreeHwMixingStaticBuffers   ]));Add(Format('%d'#9'dwFreeHwMixingStreamingBuffers', [capInfo.dwFreeHwMixingStreamingBuffers]));Add(Format('%d'#9'dwMaxHw3DAllBuffers',            [capInfo.dwMaxHw3DAllBuffers           ]));Add(Format('%d'#9'dwMaxHw3DStaticBuffers',         [capInfo.dwMaxHw3DStaticBuffers        ]));Add(Format('%d'#9'dwMaxHw3DStreamingBuffers',      [capInfo.dwMaxHw3DStreamingBuffers     ]));Add(Format('%d'#9'dwFreeHw3DAllBuffers',           [capInfo.dwFreeHw3DAllBuffers          ]));Add(Format('%d'#9'dwFreeHw3DStaticBuffers',        [capInfo.dwFreeHw3DStaticBuffers       ]));Add(Format('%d'#9'dwFreeHw3DStreamingBuffers',     [capInfo.dwFreeHw3DStreamingBuffers    ]));Add(Format('%d'#9'dwTotalHwMemBytes',              [capInfo.dwTotalHwMemBytes             ]));Add(Format('%d'#9'dwFreeHwMemBytes',               [capInfo.dwFreeHwMemBytes              ]));Add(Format('%d'#9'dwMaxContigFreeHwMemBytes',      [capInfo.dwMaxContigFreeHwMemBytes     ]));Add(Format('%d'#9'dwUnlockTransferRateHwBuffers',  [capInfo.dwUnlockTransferRateHwBuffers ]));Add(Format('%d'#9'dwPlayCpuOverheadSwBuffers',     [capInfo.dwPlayCpuOverheadSwBuffers    ]));end;
end;end.

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