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

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.

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