用多媒體庫 Bass.dll 播放 mp3 [4] – 顯示與設定播放進度

//擷取檔案流的長度, 單位是位元組function BASS_ChannelGetLength(  handle: DWORD; {流控制代碼}  mode: DWORD    {擷取模式; 有兩種選擇, 但對 HSTREAM 流只能使用 BASS_POS_BYTE}): QWORD; stdcall; external bassdll;//擷取流的當前指標位置, 單位是位元組function BASS_ChannelGetPosition(  handle: DWORD; {流控制代碼}  mode: DWORD    {擷取模式; 有兩種選擇, 但對 HSTREAM 流只能使用 BASS_POS_BYTE}): QWORD; stdcall; external bassdll;//根據流的指標位置來擷取時間點, 單位是秒, 是非常精確的浮點數function BASS_ChannelBytes2Seconds(  handle: DWORD; {流控制代碼}  pos: QWORD     {流的指標位置, 單位是位元組, QWORD = Int64}): Double; stdcall;external bassdll;//和 BASS_ChannelBytes2Seconds 相反, BASS_ChannelSeconds2Bytes 可以通過時間擷取流的指標位置.function BASS_ChannelSeconds2Bytes(  handle: DWORD;  pos: Double): QWORD; stdcall;external bassdll;//和 BASS_ChannelGetPosition 相反, BASS_ChannelSetPosition 可以設定流的指標位置.function BASS_ChannelSetPosition(  handle: DWORD;  pos: QWORD;  mode: DWORD): BOOL; stdcall; external bassdll;
//要擷取音樂的總時間可以:BASS_ChannelBytes2Seconds(hs, BASS_ChannelGetLength(hs, BASS_POS_BYTE));//要擷取音樂播放的目前時間可以:BASS_ChannelBytes2Seconds(hs, BASS_ChannelGetPosition(hs, BASS_POS_BYTE));

本例:

代碼檔案:

unit Unit1;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, StdCtrls, ExtCtrls;type  TForm1 = class(TForm)    OpenDialog1: TOpenDialog;    Timer1: TTimer;    Button1: TButton;    Button2: TButton;    Button3: TButton;    ScrollBar1: TScrollBar;    procedure FormCreate(Sender: TObject);    procedure Button1Click(Sender: TObject);    procedure Button2Click(Sender: TObject);    procedure Button3Click(Sender: TObject);    procedure Timer1Timer(Sender: TObject);    procedure ScrollBar1Scroll(Sender: TObject; ScrollCode: TScrollCode;      var ScrollPos: Integer);    procedure FormDestroy(Sender: TObject);  end;var  Form1: TForm1;implementation{$R *.dfm}uses Bass;var  hs: HSTREAM;  {流控制代碼}  time: Double; {樂曲總時間}procedure TForm1.FormCreate(Sender: TObject);begin  Timer1.Interval := 100;  Timer1.Enabled := False;  ScrollBar1.Enabled := False;  if HiWord(BASS_GetVersion)  BASSVERSION then    MessageBox(0, '"Bass.dll" 檔案版本不合適! ', nil, MB_ICONERROR);  if not BASS_Init(-1, 44100, 0, 0, nil) then    ShowMessage('初始化錯誤');end;{開啟}procedure TForm1.Button1Click(Sender: TObject);var  Mp3Path: AnsiString;begin  BASS_StreamFree(hs);  Timer1.Enabled := False;  ScrollBar1.Enabled := False;  OpenDialog1.Filter := 'Mp3 檔案(*.mp3)|*.mp3|Wav 檔案(*.wav)|*wav';  if OpenDialog1.Execute then    Mp3Path := AnsiString(OpenDialog1.FileName);  hs := BASS_StreamCreateFile(False, PAnsiChar(Mp3Path), 0, 0, 0);  if hs 

表單檔案:

object Form1: TForm1  Left = 205  Top = 107  Caption = 'Form1'  ClientHeight = 88  ClientWidth = 393  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 Button1: TButton    Left = 65    Top = 17    Width = 75    Height = 25    Caption = #25171#24320    TabOrder = 0    OnClick = Button1Click  end  object Button2: TButton    Left = 161    Top = 17    Width = 75    Height = 25    Caption = #25773#25918    TabOrder = 1    OnClick = Button2Click  end  object Button3: TButton    Left = 257    Top = 17    Width = 75    Height = 25    Caption = #26242#20572    TabOrder = 2    OnClick = Button3Click  end  object ScrollBar1: TScrollBar    Left = 8    Top = 56    Width = 377    Height = 17    PageSize = 0    TabOrder = 3    OnScroll = ScrollBar1Scroll  end  object OpenDialog1: TOpenDialog    Left = 40    Top = 40  end  object Timer1: TTimer    OnTimer = Timer1Timer    Left = 80    Top = 48  endend