Get Wave Lenght

uses MMSystem

public
    { Public declarations }
    procedure GetWaveLength;
    procedure OpenMedia(FileName: string);
    procedure SetMediaTimeFormat;
    procedure CloseMedia;
    function GetMediaStatus(StatusItem: DWORD): DWORD;
    
type
  EMyMCIException = class(Exception);

var
  Form1: TForm1;
  FDeviceID: Word;
  MyError, dwFlags: Longint;
  
//

procedure TForm1.SetMediaTimeFormat;
var
  MySetParms: TMCI_Set_Parms;
begin
  if FDeviceID <> 0 then
  begin
    dwFlags := MCI_WAIT or MCI_SET_TIME_FORMAT;
    MySetParms.dwCallback := Handle; // TForm1.Handle
    MySetParms.dwTimeFormat := MCI_FORMAT_MILLISECONDS;
    MyError := mciSendCommand(FDeviceID, MCI_SET, dwFlags,
      Longint(@MySetParms));
    if MyError <> 0 then
      raise EMyMCIException.Create('Status Failed');
  end;
end;

procedure TForm1.OpenMedia(FileName: string);
var
  MyOpenParms: TMCI_Open_Parms;
begin
  with MyOpenParms do
  begin
    dwCallback := Handle; // TForm1.Handle
    lpstrDeviceType := PChar('WaveAudio');
    lpstrElementName := PChar(FileName);
  end; {with MyOpenParms}
  dwFlags := MCI_WAIT or MCI_OPEN_ELEMENT or MCI_OPEN_TYPE;
  MyError := mciSendCommand(0, MCI_OPEN, dwFlags, Longint(@MyOpenParms));
  // one could use mciSendCommand(DevId, etc here to specify a particular

  if MyError = 0 then
    FDeviceID := MyOpenParms.wDeviceID
  else
    raise EMyMCIException.Create('Open Failed');
end;

procedure TForm1.GetWaveLength;
var
  WaveLen: DWORD;
begin
  OpenMedia('C:\My.wav');
  SetMediaTimeFormat;
  WaveLen := GetMediaStatus(MCI_STATUS_LENGTH);
  CloseMedia;
  Form1.label1.Caption := IntToStr(WaveLen) + 'mS';
end;

function TForm1.GetMediaStatus(StatusItem: DWORD): DWORD;
var
  MyStatusParms: TMCI_Status_Parms;
begin
  if FDeviceID <> 0 then
  begin
    dwFlags := MCI_WAIT or MCI_STATUS_ITEM;
    MyStatusParms.dwCallback := Handle; // TForm1.Handle
    MyStatusParms.dwItem := StatusItem;
    MyError := mciSendCommand(FDeviceID, MCI_STATUS, dwFlags,
      Longint(@MyStatusParms));
    if MyError = 0 then
      Result := MyStatusParms.dwReturn
    else
    begin
      raise EMyMCIException.Create('Status Failed');
    end;
  end;
end;

procedure TForm1.CloseMedia;
var
  MyGenParms: TMCI_Generic_Parms;
begin
  if FDeviceID <> 0 then
  begin
    dwFlags := 0;
    MyGenParms.dwCallback := Handle; // TForm1.Handle
    MyError := mciSendCommand(FDeviceID, MCI_CLOSE, dwFlags,
      Longint(@MyGenParms));
    if MyError = 0 then
      FDeviceID := 0
    else
    begin
      raise EMyMCIException.Create('Close Failed');
    end;
  end;
end;