Delphi中用多媒體庫Bass.dll播放mp3 [12] - 繪制動態頻譜 FFT

本例效果圖:

代碼文件:

unit Unit1;
interface
uses
　 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　 Dialogs, StdCtrls, ExtCtrls, ComCtrls;
type
　 TForm1 = class(TForm)
　　 OpenDialog1: TOpenDialog;
　　 Timer1: TTimer;
　　 PaintBox1: TPaintBox;
　　 Button1: TButton;
　　 Button2: TButton;
　　 Button3: TButton;
　　 procedure FormCreate(Sender: TObject);
　　 procedure Button1Click(Sender: TObject);
　　 procedure Button2Click(Sender: TObject);
　　 procedure Button3Click(Sender: TObject);
　　 procedure FormDestroy(Sender: TObject);
　　 procedure PaintBox1Paint(Sender: TObject);
　　 procedure Timer1Timer(Sender: TObject);
　 end;
var
　 Form1: TForm1;
implementation
{$R *.dfm}
uses Bass;
var
　 hs: HSTREAM;　{流句柄}
　 FFTData: array[0..512] of Single;
　 bit: TBitmap;
　 FFTPeacks　: array [0..128] of Integer;
　 FFTFallOff : array [0..128] of Integer;
procedure TForm1.FormCreate(Sender: TObject);
begin
　 Timer1.Enabled := False;
　 Timer1.Interval := 30;
　 bit := TBitmap.Create;
　 PaintBox1.Align := alTop;
　 if HiWord(BASS_GetVersion) <> BASSVERSION then
　　 MessageBox(0, '"Bass.dll" 文件版本不合適! ', nil, MB_ICONERROR);
　 if not BASS_Init(-1, 44100, 0, 0, nil) then ShowMessage('初始化錯誤');
end;
{打開}
procedure TForm1.Button1Click(Sender: TObject);
var
　 Mp3Path: AnsiString;
begin
　 BASS_StreamFree(hs);
　 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 := '打開失敗'
　 else begin
　　 Text := string(Mp3Path);
　　 bit.Free;
　　 bit := TBitmap.Create;
　　 PaintBox1.Repaint;
　 end;
end;
{播放}
procedure TForm1.Button2Click(Sender: TObject);
begin
　 Timer1.Enabled := True;
　 BASS_ChannelPlay(hs, False);
end;
{暫停}
procedure TForm1.Button3Click(Sender: TObject);
begin
　 Timer1.Enabled := False;
　 BASS_ChannelPause(hs);
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
　 BASS_Free;
　 bit.Free;
end;
{刷新}
procedure TForm1.PaintBox1Paint(Sender: TObject);
begin
　 PaintBox1.Canvas.StretchDraw(Bounds(0, 0, PaintBox1.Width, PaintBox1.Height), bit);
end;
{繪制 FFT}
procedure TForm1.Timer1Timer(Sender: TObject);
const
　 w = 8;
var
　 i,di: Integer;
begin
　 if BASS_ChannelIsActive(hs) <> BASS_ACTIVE_PLAYING then Exit;
　 BASS_ChannelGetData(hs, @FFTData, BASS_DATA_FFT1024);
　 bit.Width := PaintBox1.Width;
　 bit.Height := PaintBox1.Height;
　 bit.Canvas.Brush.Color := clBlack;
　 bit.Canvas.FillRect(Rect(0, 0, bit.Width, bit.Height));
　 bit.Canvas.Pen.Color := clLime;
　 for i := 0 to Length(FFTData) - 1 do
　 begin
　　 di := Trunc(Abs(FFTData[i]) * 500);
　　 if di > bit.Height then di := bit.Height;
　　 if di >= FFTPeacks[i] then FFTPeacks[i] := di else FFTPeacks[i] := FFTPeacks[i] - 1;
　　 if di >= FFTFallOff[i] then FFTFallOff[i] := di else FFTFallOff[i] := FFTFallOff[i] - 3;
　　 if (bit.Height - FFTPeacks[i]) > bit.Height then FFTPeacks[i] := 0;
　　 if (bit.Height - FFTFallOff[i]) > bit.Height then FFTFallOff[i] := 0;
//　　bit.Canvas.MoveTo(i, bit.Height);
//　　bit.Canvas.LineTo(i, bit.Height - FFTFallOff[i]);
//　　bit.Canvas.Pixels[i, bit.Height - FFTPeacks[i]] := bit.Canvas.Pen.Color;
　　 bit.Canvas.Pen.Color := bit.Canvas.Pen.Color;
　　 bit.Canvas.MoveTo(i * (w + 1), bit.Height - FFTPeacks[i]);
　　 bit.Canvas.LineTo(i * (w + 1) + w, bit.Height - FFTPeacks[i]);
　　 bit.Canvas.Pen.Color := bit.Canvas.Pen.Color;
　　 bit.Canvas.Brush.Color := bit.Canvas.Pen.Color;
　　 bit.Canvas.Rectangle(i * (w + 1), bit.Height - FFTFallOff[i], i * (w + 1) + w, bit.Height);
　 end;
　 BitBlt(PaintBox1.Canvas.Handle, 0, 0, PaintBox1.Width, PaintBox1.Height, bit.Canvas.Handle, 0, 0, SRCCOPY);
end;
end.

窗體文件:

object Form1: TForm1
　 Left = 222
　 Top = 114
　 Caption = 'Form1'
　 ClientHeight = 154
　 ClientWidth = 476
　 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 PaintBox1: TPaintBox
　　 Left = 16
　　 Top = 0
　　 Width = 105
　　 Height = 105
　　 OnPaint = PaintBox1Paint
　 end
　 object Button1: TButton
　　 Left = 109
　　 Top = 117
　　 Width = 75
　　 Height = 25
　　 Caption = #25171#24320
　　 TabOrder = 0
　　 OnClick = Button1Click
　 end
　 object Button2: TButton
　　 Left = 206
　　 Top = 117
　　 Width = 75
　　 Height = 25
　　 Caption = #25773#25918
　　 TabOrder = 1
　　 OnClick = Button2Click
　 end
　 object Button3: TButton
　　 Left = 303
　　 Top = 117
　　 Width = 75
　　 Height = 25
　　 Caption = #26242#20572
　　 TabOrder = 2
　　 OnClick = Button3Click
　 end
　 object OpenDialog1: TOpenDialog
　　 Left = 128
　　 Top = 24
　 end
　 object Timer1: TTimer
　　 OnTimer = Timer1Timer
　　 Left = 128
　　 Top = 72
　 end
end