用多媒体库 Bass.dll 播放 mp3 [8] - 实时显示左右声道的峰值

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, ExtCtrls, ComCtrls;



type

  TForm1 = class(TForm)

    OpenDialog1: TOpenDialog;

    Timer1: TTimer;

    Button1: TButton;

    Button2: TButton;

    Button3: TButton;

    ProgressBar1: TProgressBar;

    ProgressBar2: TProgressBar;

    procedure FormCreate(Sender: TObject);

    procedure Button1Click(Sender: TObject);

    procedure Button2Click(Sender: TObject);

    procedure Button3Click(Sender: TObject);

    procedure FormDestroy(Sender: TObject);

    procedure Timer1Timer(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses Bass;



var

  hs: HSTREAM;  {流句柄}



procedure TForm1.FormCreate(Sender: TObject);

begin

  Timer1.Interval := 100;

  Timer1.Enabled := False;

  ProgressBar1.Align := alLeft;

  ProgressBar2.Align := alRight;

  ProgressBar1.Orientation := pbVertical;

  ProgressBar2.Orientation := pbVertical;

  ProgressBar1.Width := 20;

  ProgressBar2.Width := 20;

  ProgressBar1.Max := MAXWORD div 2;

  ProgressBar2.Max := MAXWORD div 2;



  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;

begin

  BASS_StreamFree(hs);

  Timer1.Enabled := False;



  OpenDialog1.Filter := 'Mp3 文件(*.mp3)|*.mp3|Wav 文件(*.wav)|*wav';

  if OpenDialog1.Execute then

    Mp3Path := AnsiString(OpenDialog1.FileName);



  hs := BASS_StreamCreateFile(False, PAnsiChar(Mp3Path), 0, 0, 0);

  if hs < BASS_ERROR_ENDED then

    Text := '打开失败'

  else

    Text := Mp3Path;

end;



{播放}

procedure TForm1.Button2Click(Sender: TObject);

begin

  BASS_ChannelPlay(hs, False);

  Timer1.Enabled := True;

end;



{暂停}

procedure TForm1.Button3Click(Sender: TObject);

begin

  BASS_ChannelPause(hs);

  Timer1.Enabled := False;

end;



{显示左右声道的峰值}

procedure TForm1.Timer1Timer(Sender: TObject);

var

  Level: Cardinal;

begin

  Level := BASS_ChannelGetLevel(hs); {其低16位为左声道峰值; 高16位为右声道峰值}

  ProgressBar1.Position := LoWord(Level);

  ProgressBar2.Position := HiWord(Level);

end;



procedure TForm1.FormDestroy(Sender: TObject);

begin

  BASS_Free;

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 222

  Top = 114

  Caption = 'Form1'

  ClientHeight = 113

  ClientWidth = 243

  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 = 83

    Top = 17

    Width = 75

    Height = 25

    Caption = #25171#24320

    TabOrder = 0

    OnClick = Button1Click

  end

  object Button2: TButton

    Left = 83

    Top = 48

    Width = 75

    Height = 25

    Caption = #25773#25918

    TabOrder = 1

    OnClick = Button2Click

  end

  object Button3: TButton

    Left = 83

    Top = 79

    Width = 75

    Height = 25

    Caption = #26242#20572

    TabOrder = 2

    OnClick = Button3Click

  end

  object ProgressBar1: TProgressBar

    Left = 8

    Top = 74

    Width = 69

    Height = 17

    TabOrder = 3

  end

  object ProgressBar2: TProgressBar

    Left = 164

    Top = 74

    Width = 77

    Height = 17

    TabOrder = 4

  end

  object OpenDialog1: TOpenDialog

    Left = 192

    Top = 8

  end

  object Timer1: TTimer

    OnTimer = Timer1Timer

    Left = 40

    Top = 8

  end

end