操作 Wave 文件(13): waveOutGetVolume、waveOutSetVolume

左右声道的音量是单调的; 表示音量的 32 位整数的低 16 位是左声道、高 16 位是右声道.

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代码文件:

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unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls;



type

  TForm1 = class(TForm)

    Button1: TButton;

    Button2: TButton;

    Button3: TButton;

    ScrollBar1: TScrollBar;

    ScrollBar2: TScrollBar;

    procedure FormCreate(Sender: TObject);

    procedure Button1Click(Sender: TObject);

    procedure Button2Click(Sender: TObject);

    procedure Button3Click(Sender: TObject);

    procedure ScrollBar1Change(Sender: TObject);

    procedure FormDestroy(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses MMSystem;



function GetWaveFmtData(path: string; var fmt: TWaveFormatEx; var buf: TBytes): Boolean;

var

  hFile: HMMIO;

  ckiRIFF,ckiFmt,ckiData: TMMCKInfo;

begin

  Result := False;

  hFile := mmioOpen(PChar(path), nil, MMIO_READ);

  if hFile = 0 then Exit;



  ZeroMemory(@ckiRIFF, SizeOf(TMMCKInfo));

  ZeroMemory(@ckiFmt, SizeOf(TMMCKInfo));

  ZeroMemory(@ckiData, SizeOf(TMMCKInfo));



  ckiRIFF.fccType := mmioStringToFOURCC('WAVE', 0);

  ckiFmt.ckid := mmioStringToFOURCC('fmt', 0);

  ckiData.ckid := mmioStringToFOURCC('data', 0);



  ZeroMemory(@fmt, SizeOf(TWaveFormatEx));



  mmioDescend(hFile, @ckiRIFF, nil, MMIO_FINDRIFF);



  if (ckiRIFF.ckid = FOURCC_RIFF) and (ckiRIFF.fccType = mmioStringToFOURCC('WAVE',0)) and

     (mmioDescend(hFile, @ckiFmt, @ckiRIFF, MMIO_FINDCHUNK) = MMSYSERR_NOERROR) and

     (mmioRead(hFile, @fmt, ckiFmt.cksize) = ckiFmt.cksize) and

     (mmioAscend(hFile, @ckiFmt, 0) = MMSYSERR_NOERROR) and

     (mmioDescend(hFile, @ckiData, @ckiRIFF, MMIO_FINDCHUNK) = MMSYSERR_NOERROR) then

  begin

    SetLength(buf, ckiData.cksize);

    Result := (mmioRead(hFile, PAnsiChar(buf), ckiData.cksize) = ckiData.cksize);

  end;



  mmioClose(hFile, 0);

end;



//------------------------------------------------------------------------------

var

  wh: TWaveHdr;

  hWaveOut: HWAVE;

  fmt: TWaveFormatEx;

  buf: TBytes;



procedure TForm1.FormCreate(Sender: TObject);

begin

  Button1.Caption := '打开并播放';

  Button2.Caption := '暂停';

  Button3.Caption := '继续';



  ScrollBar1.Min := 0;

  ScrollBar1.Max := 100;

  ScrollBar2.Min := 0;

  ScrollBar2.Max := 100;



  ScrollBar2.OnChange := ScrollBar1.OnChange;

end;



procedure TForm1.ScrollBar1Change(Sender: TObject);

var

  L,R: Word;

begin

  if hWaveOut = 0 then Exit;

  L := Trunc(ScrollBar1.Position / 100 * MAXWORD);

  R := Trunc(ScrollBar2.Position / 100 * MAXWORD);

  waveOutSetVolume(hWaveOut, MakeLong(L, R));

end;



procedure WaveProc(hWave: HWAVE; uMsg, dwInstance, dwParam1, dwParam2: DWORD); stdcall;

begin

  case uMsg of

    MM_WOM_DONE: waveOutUnprepareHeader(hWave, PWaveHdr(dwParam1), SizeOf(TWaveHdr));

  end;

end;



procedure TForm1.Button1Click(Sender: TObject);

const

  path = 'C:\WINDOWS\Media\Windows XP 启动.wav';

var

  volume: DWORD;

begin

  GetWaveFmtData(path, fmt, buf);



  wh.lpData := PAnsiChar(buf);

  wh.dwBufferLength := Length(buf);

  wh.dwBytesRecorded := 0;

  wh.dwUser := 0;

  wh.dwFlags := WHDR_BEGINLOOP or WHDR_ENDLOOP;

  wh.dwLoops := 3;

  wh.lpNext := nil;

  wh.reserved := 0;



  waveOutOpen(@hWaveOut, WAVE_MAPPER, @fmt, DWORD(@WaveProc), 0, CALLBACK_FUNCTION);

  waveOutGetVolume(hWaveOut, @volume);



  ScrollBar1.Position := Trunc(LoWord(volume) / MAXWORD * 100);

  ScrollBar2.Position := Trunc(HiWord(volume) / MAXWORD * 100);



  waveOutPrepareHeader(hWaveOut, @wh, SizeOf(TWaveHdr));

  waveOutWrite(hWaveOut, @wh, SizeOf(TWaveHdr));

end;



//暂停

procedure TForm1.Button2Click(Sender: TObject);

begin

  waveOutPause(hWaveOut);

end;



//继续

procedure TForm1.Button3Click(Sender: TObject);

begin

  waveOutRestart(hWaveOut);

end;



procedure TForm1.FormDestroy(Sender: TObject);

begin

  if hWaveOut <> 0 then waveOutClose(hWaveOut);

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 182

  ClientWidth = 342

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  OnCreate = FormCreate

  OnDestroy = FormDestroy

  PixelsPerInch = 96

  TextHeight = 13

  object Button1: TButton

    Left = 32

    Top = 24

    Width = 75

    Height = 25

    Caption = #25171#24320#24182#25773#25918

    TabOrder = 0

    OnClick = Button1Click

  end

  object Button2: TButton

    Left = 136

    Top = 24

    Width = 75

    Height = 25

    Caption = #26242#20572

    TabOrder = 1

    OnClick = Button2Click

  end

  object Button3: TButton

    Left = 240

    Top = 24

    Width = 75

    Height = 25

    Caption = #32487#32493

    TabOrder = 2

    OnClick = Button3Click

  end

  object ScrollBar1: TScrollBar

    Left = 32

    Top = 80

    Width = 283

    Height = 17

    PageSize = 0

    TabOrder = 3

    OnChange = ScrollBar1Change

  end

  object ScrollBar2: TScrollBar

    Left = 32

    Top = 120

    Width = 283

    Height = 17

    PageSize = 0

    TabOrder = 4

  end

end