使用Mpegplayer控件编写容易的mp3播放程序

1.前言

---- mp3因其较高的压缩率,较好的音质,成为越来越多的使用者的喜爱,用自己编制的mp3播放器听mp3音乐一定很有乐趣.我以下介绍一个用delphi编制的简单mp3播放器,因为mp3音乐的解码比较复杂,普通的程序员很难编制其解码程序,但不要紧,我们可以用别人写好的解码程序来完成我们的程序.

---- 2.设计构思

---- 我们使用mpegdll.dll来解码(很多国产的mp3播放器都用它),mpegdll.dll的作者提供了它的delphi的控件,在各大delphi网站都有下载,或在作者的主页http://www.ig.com.ua/wabbit/programs/workshop.html下载之后,我们安装控件(必须delphi3.0以上),在component中选择install component,安装控件包中的mpegplayer.dcu,安装完成后在控件栏里多出一个add-ons来,控件就在里面.

---- 介绍一下用到的参数

mpeg.streamname 所要播放的文件名
mpeg.length 文件程度
mpeg.bitrate 压缩位率
mpeg.frequency 压缩频率
mpeg.layer 压缩层次
mpeg.mode 压缩模式
mpeg.pathtodll dll文件的路径

---- 新建一个from,放入6个label,5个button,1个checkbox,1个mpeg,1个time,1个trackbar,1个opendialog控件调整为适当的布局,点击opendialog1使*.mp3成为打开文件的后缀名.调整5个button,把其属性name改为 openbutton,pausebutton,stopbutton,playbutton和exitbutton,并把caption改为播放,暂停,停止,打开,和退出. 使3个label的caption成为,压缩位率,压缩频率,压缩层次,调整其他3个label使label4对应label1,label5对应label2,label6对应label3 caption为空,autosize为true,trackbar的tickstyle设为tsNone,chickbox的caption设为循环播放,timer的ontimer设为timer1timer
---- 3.程序清单如下

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Classes,
Graphics, Controls, Forms, Dialogs,
ExtCtrls, MPEGPlayer,Gauges,
ComCtrls,Mask, StdCtrls;

type
TForm1 = class(TForm)
Label1: TLabel;
Label2: TLabel;
Label3: TLabel;
Label4: TLabel;
Label5: TLabel;
openButton: TButton;
playButton: TButton;
pauseButton: TButton;
stopButton: TButton;
exitButton: TButton;
CheckBox1: TCheckBox;
TrackBar1: TTrackBar;
MPEG: TMPEGPlayer;
Timer1: TTimer;
OpenDialog1: TOpenDialog;
Label6: TLabel;
procedure exitButtonClick(Sender: TObject);
procedure openButtonClick(Sender: TObject);
procedure playButtonClick(Sender: TObject);
procedure pauseButtonClick(Sender: TObject);
procedure stopButtonClick(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure TrackBar1Change(Sender: TObject);
procedure Timer1Timer(Sender: TObject);
procedure FormClose(Sender:
TObject; var Action: TCloseAction);
private
{ Private declarations }
dontseek:boolean;
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.DFM}


procedure TForm1.exitButtonClick(Sender: TObject);
begin
close;
end;

procedure TForm1.openButtonClick(Sender: TObject);
var s:string;
begin
if not opendialog1.execute then exit;
mpeg.autoplay:=false;
mpeg.streamname:=opendialog1.filename;
mpeg.open;
trackbar1.Max:=mpeg.length;
trackbar1.position:=0;
str(trackbar1.max,s);
playbutton.Enabled:=true;
stopbutton.enabled:=true;
pausebutton.Enabled:=true;
end;

procedure TForm1.playButtonClick(Sender: TObject);
var a,b,c:string;
begin
playbutton.Enabled:=false;
openbutton.Enabled:=false;
mpeg.Play;
str(mpeg.Bitrate,a);
label4.Caption:=a;
str(mpeg.Frequency,b);
label5.caption:=b;
str(mpeg.layer,c);
label6.caption:=c;
end;
procedure TForm1.pauseButtonClick(Sender: TObject);
begin
mpeg.paused:=not (mpeg.Paused);
end;

procedure TForm1.stopButtonClick(Sender: TObject);
begin
if mpeg.mode>2 then
begin
mpeg.stop;
mpeg.close;
end;
trackbar1.Position:=0;
openbutton.Enabled:=true;
playbutton.enabled:=false;
stopbutton.enabled:=false;
pausebutton.enabled:=false;
label4.Caption:='';
label5.Caption:='';
label6.Caption:='';
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
mpeg.pathtodll:='';
//存放dll闻家的路径本例程序和dll在同一路径下
//dll一定要放在程序同一目录,否则不能编译
mpeg.init;
playbutton.Enabled :=false;
pausebutton.enabled:=false;
stopbutton.enabled:=false;
end;
procedure TForm1.FormClose(Sender:
TObject; var Action: TCloseAction);
begin
mpeg.deinit;
end;
procedure TForm1.TrackBar1Change(Sender: TObject);
begin
if not(dontseek) then
if (mpeg.mode=3)or((mpeg.mode=4))
then mpeg.CurrentPosition:=trackbar1.Position;
end;
procedure TForm1.Timer1Timer(Sender: TObject);
var a,b,c:string;
begin
if (mpeg.mode=3) then
begin
dontseek:=true;
trackbar1.Position:=mpeg.CurrentPosition;
dontseek:=false;

end;
if mpeg.PlayStopped then
begin
if checkbox1.Checked then
begin
mpeg.Play;
playbutton.Enabled:=false;
openbutton.Enabled:=false;
str(mpeg.Bitrate,a);
label4.Caption:=a;
str(mpeg.Frequency,b);
label5.caption:=b;
str(mpeg.layer,c);
label6.caption:=c;
end
else
begin
mpeg.close;
trackbar1.Position:=0;
openbutton.Enabled:=true;
playbutton.Enabled :=false;
pausebutton.enabled:=false;
stopbutton.enabled:=false;
label4.Caption:='';
label5.Caption:='';
label6.Caption:='';
end;
end;
end;
end.
---- 以上是一个简单的mp3播放器的例程,mpegplayer是一个强大的控件可以实现很多功能,如多曲播放,请大家自己研究把,愿大家都能做出很好的mp3播放器

……