用多媒体库 Bass.dll 播放 mp3 [15] - 设置与获取播放速度

本例效果图:

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代码文件:

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unit Unit1;interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, StdCtrls, ComCtrls;typeTForm1 = class(TForm)OpenDialog1: TOpenDialog;Button1: TButton;Button2: TButton;Button3: TButton;TrackBar1: TTrackBar;Label1: TLabel;Button4: TButton;procedure FormCreate(Sender: TObject);procedure Button1Click(Sender: TObject);procedure Button2Click(Sender: TObject);procedure Button3Click(Sender: TObject);procedure TrackBar1Change(Sender: TObject);procedure FormDestroy(Sender: TObject);procedure Button4Click(Sender: TObject);end;varForm1: TForm1;implementation{$R *.dfm}uses Bass;varhs: HSTREAM;  {流句柄}procedure TForm1.FormCreate(Sender: TObject);
beginTrackBar1.ShowSelRange := False;TrackBar1.Height := 23;TrackBar1.Max := 100000;TrackBar1.Min := 100;TrackBar1.Position := 44100;if HiWord(BASS_GetVersion) <> BASSVERSION thenMessageBox(0, '"Bass.dll" 文件版本不合适! ', nil, MB_ICONERROR);if not BASS_Init(-1, 44100, 0, 0, nil) thenShowMessage('初始化错误');
end;{打开}
procedure TForm1.Button1Click(Sender: TObject);
varMp3Path: AnsiString;
beginBASS_StreamFree(hs);OpenDialog1.Filter := 'Mp3 文件(*.mp3)|*.mp3|Wav 文件(*.wav)|*wav';if OpenDialog1.Execute thenMp3Path := AnsiString(OpenDialog1.FileName);hs := BASS_StreamCreateFile(False, PAnsiChar(Mp3Path), 0, 0, 0);if hs < BASS_ERROR_ENDED thenText := '打开失败'else beginText := string(Mp3Path);Button4.Click;end;
end;{播放}
procedure TForm1.Button2Click(Sender: TObject);
beginBASS_ChannelPlay(hs, False);
end;{暂停}
procedure TForm1.Button3Click(Sender: TObject);
beginBASS_ChannelPause(hs);
end;{原速}
procedure TForm1.Button4Click(Sender: TObject);
beginTrackBar1.Position := 44100;
end;{设置和获取播放速度}
procedure TForm1.TrackBar1Change(Sender: TObject);
varfreq: Single;
beginfreq := 44100;BASS_ChannelSlideAttribute(hs, BASS_ATTRIB_FREQ, TrackBar1.Position, 0);BASS_ChannelGetAttribute(hs, BASS_ATTRIB_FREQ, freq);Label1.Caption := Format('当前速度比例: %f%%', [freq/44100]);
end;procedure TForm1.FormDestroy(Sender: TObject);
beginBASS_Free;
end;end.

窗体文件:

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object Form1: TForm1Left = 205Top = 107Caption = 'Form1'ClientHeight = 119ClientWidth = 286Color = clBtnFaceFont.Charset = DEFAULT_CHARSETFont.Color = clWindowTextFont.Height = -11Font.Name = 'Tahoma'Font.Style = []OldCreateOrder = FalsePosition = poDesignedOnCreate = FormCreateOnDestroy = FormDestroyPixelsPerInch = 96TextHeight = 13object Label1: TLabelLeft = 32Top = 59Width = 31Height = 13Caption = 'Label1'endobject Button1: TButtonLeft = 24Top = 17Width = 75Height = 25Caption = #25171#24320TabOrder = 0OnClick = Button1Clickendobject Button2: TButtonLeft = 105Top = 17Width = 75Height = 25Caption = #25773#25918TabOrder = 1OnClick = Button2Clickendobject Button3: TButtonLeft = 186Top = 17Width = 75Height = 25Caption = #26242#20572TabOrder = 2OnClick = Button3Clickendobject TrackBar1: TTrackBarLeft = 24Top = 78Width = 237Height = 32TabOrder = 3OnChange = TrackBar1Changeendobject Button4: TButtonLeft = 186Top = 48Width = 75Height = 25Caption = #21407#36895TabOrder = 4OnClick = Button4Clickendobject OpenDialog1: TOpenDialogLeft = 256end
end