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

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.

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