怎么取得一个mp3或wav文件的音频长度？

[bluemarry]

如题～

[bluemarry]

[Quote=引用 4 楼 mdejtod 的回复:]
时间？大小？？
[/Quote]

＂音频长度＂
当然是指时间啦～

[yanglongorg]

function FileSize(var F): Integer;

[success000]

ding

[dlschan]

ding

[mdejtod]

时间？大小？？

[shuihan20e]

http://www.2ccc.com/search.asp?KeyWord=mp3&Submit=%BF%EC%CB%D9%CB%D1%CB%F7

[xzhifei]

//返回秒数

function ReadWaveTime(FileName: string): Double;
type
  TWaveFileHeader = packed record
    FType: Integer;
    Size: Longint;
    RType: Integer;
  end;

  TWaveChunkHeader = packed record
    CType: Longint;
    Size: Longint;
  end;

const
  ID_RIFF = Ord('R') + Ord('I') * $100 + Ord('F') * $10000 + Ord('F') * $1000000;
  ID_WAVE = Ord('W') + Ord('A') * $100 + Ord('V') * $10000 + Ord('E') * $1000000;
  ID_FMT = Ord('f') + Ord('m') * $100 + Ord('t') * $10000 + Ord(' ') * $1000000;
  ID_FACT = Ord('f') + Ord('a') * $100 + Ord('c') * $10000 + Ord('t') * $1000000;
  ID_DATA = Ord('d') + Ord('a') * $100 + Ord('t') * $10000 + Ord('a') * $1000000;

var
  DataSize: Integer;
  Format: TWaveFormatEx;
  Stream: TFileStream;
  Header: TWaveFileHeader;
  Chunk: TWaveChunkHeader;
begin
  Result := 0;
  DataSize := 0;
  FilLChar(Format, SizeOf(Format), 0);
  Stream := TFileStream.Create(FileName, fmOpenRead or fmShareDenyNone);
  with Stream do
  try
    ReadBuffer(Header, Sizeof(Header));
    if (Header.FType <> ID_RIFF) and (Header.RType <> ID_WAVE) then
      raise Exception.Create('invalid wave file format');
    Stream.ReadBuffer(Chunk, Sizeof(Chunk));
    while Chunk.CType <> 0 do
    begin
      if Chunk.CType = ID_FMT then
        Stream.ReadBuffer(Format, Chunk.Size)
      else if Chunk.CType = ID_DATA then
      begin
        DataSize := Stream.Size - Stream.Position;
        break;
      end
      else if Chunk.CType = ID_FACT then
        Stream.Seek(Chunk.Size, soFromCurrent);
      FillChar(Chunk, SizeOf(Chunk), 0);
      Stream.ReadBuffer(Chunk, Sizeof(Chunk));
    end;
    if (DataSize <> 0) and (Format.nAvgBytesPerSec <> 0) then
      Result := DataSize / Format.nAvgBytesPerSec;
  finally
    Free;
  end;
end;
//TWaveFormatEx :
//nAvgBytesPerSec: 声音文件中声音频率每秒钟产生出的字节数 ;

[bluemarry]

谢谢楼上，wav文件测试过没问题.

不知道mp3文件的声音长度怎么取，期待高手.

[yucui]

用mmtool吧，那个控件还是很好用的。
它的demo中好像有mp3长度判断的。

[Tody Guo]

unit Unit1;

interface

uses
  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;  {流句柄}
  time: Double; {乐曲总时间}

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" 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);
  Timer1.Enabled := False;
  ScrollBar1.Enabled := False;

  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);
    time := BASS_ChannelBytes2Seconds(hs, BASS_ChannelGetLength(hs, BASS_POS_BYTE)); {总秒数}
    ScrollBar1.Max := Trunc(time * 1000);
    ScrollBar1.Enabled := True;
  end;
end;

{播放}
procedure TForm1.Button2Click(Sender: TObject);
begin
  BASS_ChannelPlay(hs, False);
  Timer1.Enabled := True;
end;

{暂停}
procedure TForm1.Button3Click(Sender: TObject);
begin
  Timer1.Enabled := False;
  BASS_ChannelPause(hs);
end;

{播放时需要的显示}
procedure TForm1.Timer1Timer(Sender: TObject);
var
  s: Double; {当前秒数}
begin
  s := BASS_ChannelBytes2Seconds(hs, BASS_ChannelGetPosition(hs, BASS_POS_BYTE));
  Text := Concat(FloatToStr(time), ' / ', FloatToStr(s));
  ScrollBar1.Position := Trunc(s * 1000);
end;

{调整播放位置}
procedure TForm1.ScrollBar1Scroll(Sender: TObject; ScrollCode: TScrollCode;
  var ScrollPos: Integer);
var
  Position: Int64;
begin
  Button3.Click;
  Position := BASS_ChannelSeconds2Bytes(hs, ScrollPos / 1000);
  BASS_ChannelSetPosition(hs, Position, BASS_POS_BYTE);
  Text := Concat(FloatToStr(time), ' / ', FloatToStr(Position / 1000));
  Timer1Timer(nil);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  BASS_Free;
end;

end.