用多媒體庫 Bass.dll 播放 mp3 [14] - 頻率均衡器

　本例效果圖:

　　代碼文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls, ComCtrls, ExtCtrls;
type
　TForm1 = class(TForm)
　　OpenDialog1: TOpenDialog;
　　Button1: TButton;
　　Button2: TButton;
　　Button3: TButton;
　　Panel1: TPanel;
　　procedure FormCreate(Sender: TObject);
　　procedure Button1Click(Sender: TObject);
　　procedure Button2Click(Sender: TObject);
　　procedure Button3Click(Sender: TObject);
　　procedure FormDestroy(Sender: TObject);
　private
　　procedure TrackChange(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses Bass;
var
　hs: HSTREAM;　{流句柄}
　parameq: BASS_DX8_PARAMEQ; {頻率均衡器的參數結構}
　fx: array[0..5] of HFX;　　{DX 的效果句柄}
　track: array[0..5] of TTrackBar;
procedure TForm1.FormCreate(Sender: TObject);
var
　i: Integer;
begin
　Panel1.Align := alRight;
　Panel1.BevelOuter := bvLowered;
　Panel1.BevelWidth := 2;
　Panel1.Caption := '';
　Panel1.Width := 6*24 + 2;
　for i := 0 to 5 do
　begin
　　track[i] := TTrackBar.Create(Self);
　　track[i].Parent := Panel1;
　　track[i].OrIEntation := trVertical;
　　track[i].Width := 23;
　　track[i].Height := Panel1.Height;
　　track[i].ShowSelRange := False;
　　track[i].Left := i * 24 + 1;
　　track[i].Max := 15;
　　track[i].Min := -15;
　　track[i].Position := 0;
　　track[i].Tag := i;
　　track[i].OnChange := Self.TrackChange;
　end;
　if HiWord(BASS_GetVersion) <> BASSVERSION then
　　MessageBox(0, '"Bass.dll" 文件版本不合適! ', nil, MB_ICONERROR);
　if not BASS_Init(-1, 44100, 0, 0, nil) then ShowMessage('初始化錯誤');
end;
{打開}
procedure TForm1.Button1Click(Sender: TObject);
var
　Mp3Path: AnsiString;
　i: Integer;
begin
　BASS_StreamFree(hs);
　OpenDialog1.Filter := 'Mp3 文件(*.mp3)|*.mp3|Wav 文件(*.wav)|*wav';
　if OpenDialog1.Execute then
　　Mp3Path := AnsiString(OpenDialog1.FileName);
　{實現混響等效果, 需要指定 BASS_SAMPLE_FX 參數}
　hs := BASS_StreamCreateFile(False, PAnsiChar(Mp3Path), 0, 0, BASS_SAMPLE_FX);
　if hs < BASS_ERROR_ENDED then
　　Text := '打開失敗'
　else begin
　　Text := string(Mp3Path);
　　{要設置多種頻率范圍, 就需要多個效果句柄}
　　for i := 0 to 5 do
　　　fx[i] := BASS_ChannelSetFX(hs, BASS_FX_DX8_PARAMEQ, 1);
　end;
end;
{播放}
procedure TForm1.Button2Click(Sender: TObject);
begin
　BASS_ChannelPlay(hs, False);
end;
{暫停}
procedure TForm1.Button3Click(Sender: TObject);
begin
　BASS_ChannelPause(hs);
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
　BASS_Free;
end;
{動態建立的 TTrackBar 要調用的事件}
procedure TForm1.TrackChange(Sender: TObject);
var
　i: Integer;
begin
　i := TTrackBar(Sender).Tag;
　parameq.fBandwidth := 20; {1 - 36}
　case i of
　　0: parameq.fCenter := 100;
　　1: parameq.fCenter := 2000;
　　2: parameq.fCenter := 4000;
　　3: parameq.fCenter := 8000;
　　4: parameq.fCenter := 10000;
　　5: parameq.fCenter := 12000;
　end;
　parameq.fGain := - TTrackBar(Sender).Position;
　BASS_FXSetParameters(fx[i], @parameq);
end;
end.窗體文件:object Form1: TForm1
　Left = 222
　Top = 114
　Caption = 'Form1'
　ClIEntHeight = 132
　ClIEntWidth = 254
　Color = clBtnFace
　Font.Charset = DEFAULT_CHARSET
　Font.Color = clWindowText
　Font.Height = -11
　Font.Name = 'Tahoma'
　Font.Style = []
　OldCreateOrder = False
　Position = poDesigned
　OnCreate = FormCreate
　OnDestroy = FormDestroy
　PixelsPerInch = 96
　TextHeight = 13
　object Button1: TButton
　　Left = 8
　　Top = 17
　　Width = 75
　　Height = 25
　　Caption = #25171#24320
　　TabOrder = 0
　　OnClick = Button1Click
　end
　object Button2: TButton
　　Left = 8
　　Top = 56
　　Width = 75
　　Height = 25
　　Caption = #25773#25918
　　TabOrder = 1
　　OnClick = Button2Click
　end
　object Button3: TButton
　　Left = 8
　　Top = 93
　　Width = 75
　　Height = 25
　　Caption = #26242#20572
　　TabOrder = 2
　　OnClick = Button3Click
　end
　object Panel1: TPanel
　　Left = 92
　　Top = 47
　　Width = 141
　　Height = 41
　　Caption = 'Panel1'
　　TabOrder = 3
　end
　object OpenDialog1: TOpenDialog
　　Left = 80
　　Top = 88
　end