用多媒体库 Bass.dll 播放 mp3 [14] - 频率均衡器

本例效果图:

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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, 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; {频率均衡器的参数结构}
  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" 文件版本不合适! ', nil, MB_ICONERROR);

  if not BASS_Init(-1, 44100, 0, 0, nil) then ShowMessage('初始化错误');
end;

{打开}
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);

  {实现混响等效果, 需要指定 BASS_SAMPLE_FX 参数}
  hs := BASS_StreamCreateFile(False, PAnsiChar(Mp3Path), 0, 0, BASS_SAMPLE_FX);

  if hs < BASS_ERROR_ENDED then
    Text := '打开失败'
  else begin
    Text := string(Mp3Path);

    {要设置多种频率范围, 就需要多个效果句柄}
    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;

{暂停}
procedure TForm1.Button3Click(Sender: TObject);
begin
  BASS_ChannelPause(hs);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  BASS_Free;
end;

{动态建立的 TTrackBar 要调用的事件}
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.

窗体文件:

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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
end