用多媒体库 Bass.dll 播放 mp3 [12] - 绘制动态频谱 FFT

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;

    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);



  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 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;



{暂停}

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;



{绘制 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.


 
   

窗体文件:

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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