Как экстрагировать аудиодорожку из AVI файла?

uses 
{...}, vfw; 

var 
  abort: Boolean; 

  {$R *.DFM} 

{Special thanks to Jailbird, who developed a big part of this Code 
Please download th vfw.pas first } 
{The 'SaveCallback' function allows the user to get the 
 process status and abort the save progress. This function 
 needn't to call by the user.} 

function SaveCallback(nPercent: Int): Bool; pascal; 
begin 
  Application.ProcessMessages; 

  Form1.Progressbar1.Position := nPercent; 
  //Save Status in Percent 
  if abort = True then 
    Result := True    
  else                //If then function returns "True", the Process will continue 
    Result := False;  
end;                  //If it returns "False" the process will abort 

{The following function needs two parameters: 

 InputFile: PChar 
  Enter a Dir + Filename of a AVI File. 

 OutputFile: PChar 
  Enter a Dir + Filename of a WAVE File where do you want to 
  put the audiodata of the movie. 

  TIP: 
  Enter jus a Filename of a WAVE File if the audiodata of the 
  movie is in uncompressed PCM Format. 

 ########################################################### 

 IMPORTANT: 
  Before calling the 'ExtractAVISound' function be sure that the 
  Inputfile has a audiotrace. 
 } 

function TForm1.ExtractAVISound(InputFile, Outputfile: PChar): Boolean; 
var 
  PFile: IAviFile; 
  PAvi: IAviStream; 
  plpOptions: PAviCompressOptions; 
begin 
  Abort := False; 

  if Fileexists(StrPas(Outputfile)) then  
  begin 
    case MessageDlg('Ausgabedatei existiert bereits. Ьberschreiben?', 
      mtWarning, [mbYes, mbNo], 0) of 
      mrYes:  
        begin 
          DeleteFile(StrPas(Outputfile)); 
        end;                             
      //Important because the function overwrite just 
      //the part of the file which is needed. 
      mrNo:  
        begin 
          Exit; 
        end; 
    end; 
  end; 

  try            
    AviFileInit;  //Init the API 
    if AviFileOpen(PFile, Inputfile, 0, nil) <> 0 then  
    begin                                               //Opens a AVI File 
      MessageDlg('Fehler beim laden des Videos. 
      Mцglicherweise wird die Datei von einem anderen Prozess verwendet.' 
        + #13#10 + 
        'SchlieЯen Sie alle in Frage kommenden Anwendungen und versuchen Sie es erneut.', 
        mtError, [mbOK], 0); 
      Result := False; 
      Exit; 
    end; 
    if AviFileGetStream(PFile, PAvi, StreamTypeAudio, 0) <> 0 then 
    begin 
      MessageDlg( 
        'Fehler beim laden des AudioStreams. Bitte ьberprьfen Sie, ob dieses Video ьber einen AudioStream verfьgt.', 
        mtError, [mbOK], 0); 
      AviFileExit; 
      Result := False; 
      Exit; 
    end; 
    //Saves the AudioStream 
    if AviSaveV(Outputfile, nil, @SaveCallback, 1, PAvi, plpOptions) <> 0 then 
    begin 
      MessageDlg('Fehler beim Speichern des AudioStreams oder Sie haben den Speichervorgang abgebrochen.', 
        mtError, [mbOK], 0); 
      AviStreamRelease(PAvi); 
      AviFileExit; 
      Result := False; 
      Exit; 
    end; 
  finally 
    AviStreamRelease(PAvi); 
    AviFileExit; 
  end; 
  Result := True;  
  //return 'TRUE' if all right 
end; 

//Example how to call the function: 

procedure TForm1.Button1Click(Sender: TObject); 
begin 
  if ExtractAVISound(PChar('D:\test.avi'), PChar('D:\test.wav')) = True then 
    ShowMessage('Audio sucessfully saved'); 
  else 
    ShowMessage('Error while saving...'); 
end;