[DELPHI] Errore "Problem downloading url"

[temporaryuser]

Ciao a tutti!
Ho trovato questo codice su internet per scaricare video da youtube

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  RegExpr,ExtActns,HTTPSend,
  Dialogs, StdCtrls, ComCtrls;

type
  TForm1 = class(TForm)
    txtLink: TEdit;
    txtVideo: TEdit;
    txtVideoTitle: TEdit;
    btnDownload: TButton;
    ProgressBar1: TProgressBar;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    SaveDialog1: TSaveDialog;
    Button1: TButton;
    Label4: TLabel;
    procedure btnExtractClick(Sender: TObject);
    procedure btnDownloadClick(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
    function formatFileName(s:String):String;
    procedure URL_OnDownloadProgress (Sender: TDownLoadURL; Progress, ProgressMax:
            Cardinal; StatusCode: TURLDownloadStatus; StatusText: String; var Cancel:
            Boolean) ;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}


function ExtractVideoTitle(s: String): String;
const
  sRegExpr = '<title>YouTube - ([^<]+)<';
var
  r: TRegExpr;
begin
  // Init
  r := TRegExpr.Create;
  try
    // Set Expression
    r.Expression := sRegExpr;
    // Extract
    if r.Exec(s) then
    begin
      // Set Result
     // showmessage('test');
      Result := r.Match[0];
      // Format
      Result := StringReplace(Result, '<title>YouTube - ', '', []);
      Result := StringReplace(Result, '<', '', []);
    end;
  finally
    r.Free;
  end;
end;

function ExtractVideoLink(s: String): String;
const
  sRegExpr1 = 'video_id":\s"([^"]+)"';
  sRegExpr2 = '"t":\s"(.*?)"'; 
var
  r: TRegExpr;
  sID, sT: String;
begin
  // Init
  r := TRegExpr.Create;
  try
    // Get ID
    // Set Expression
    r.Expression := sRegExpr1;
    // Get it
    if r.Exec(s) then
    begin
      sID := r.Match[0];
      sID := StringReplace(sID, ': ', '=', []);
      sID := StringReplace(sID, #34, '', [rfReplaceAll]);
     // showmessage('ok');
    end;
    //showmessage(sID);
    // Get T
    // Set Expression
    r.Expression := sRegExpr2;
    // Get it

    if r.Exec(s) then
    begin
      sT := r.Match[0];
      sT := StringReplace(sT, ': ', '=', []);
      sT := StringReplace(sT, #34, '', [rfReplaceAll]);
    end;

    // Set Result
    Result := 'http://youtube.com/get_video?' + sID + '&' + sT;
  finally
    r.Free;
  end;
end;



procedure TForm1.btnExtractClick(Sender: TObject);
var
  sHTTPSource:TStringList;
  HTTP: THTTPSend;
begin
  try
    sHTTPSource := TStringList.Create;
    if HttpGetText(txtLink.Text, sHTTPSource) then
    begin
      txtVideoTitle.Text := ExtractVideoTitle( sHTTPSource.Text );
      txtVideo.Text := ExtractVideoLink( sHTTPSource.Text );
    end;
  finally
    sHTTPSource.Free;
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  sHTTPSource:TStringList;
  HTTP: THTTPSend;
begin
  try
    sHTTPSource := TStringList.Create;
    //use HttpGetText to save html source into TstringList
    if HttpGetText(txtLink.Text, sHTTPSource) then
    begin
      txtVideoTitle.Text := ExtractVideoTitle( sHTTPSource.Text );
      txtVideo.Text := ExtractVideoLink( sHTTPSource.Text );
    end;
  finally
    sHTTPSource.Free;
  end;

end;

//ensure file name is acceptable by windows
function TForm1.formatFileName(s: String): String;
var
  I:Integer;
  sTemp:String;
begin
  sTemp:=StringReplace(s, ':', '', [rfReplaceAll]);
  sTemp:=StringReplace(sTemp, ' ', '_', [rfReplaceAll]);
  result := sTemp;
end;

procedure TForm1.URL_OnDownloadProgress(Sender: TDownLoadURL; Progress,
ProgressMax: Cardinal; StatusCode: TURLDownloadStatus; StatusText: String; var
Cancel: Boolean) ;
begin
  ProgressBar1.Max:= ProgressMax;
  ProgressBar1.Position:= Progress;
  application.ProcessMessages;
end;

function DoDownload(vURL, vLocation : String): Boolean;
begin
  with TDownloadURL.Create(nil) do
  try
    URL:= vURL;
    FileName := vLocation;
    OnDownloadProgress := Form1.URL_OnDownloadProgress;
    ExecuteTarget(nil) ;
  finally
    Free;
  end;
end;

procedure TForm1.btnDownloadClick(Sender: TObject);
var
  FS: TFileStream;
begin
  SaveDialog1.FileName := formatFileName(txtVideoTitle.Text);
  if SaveDialog1.Execute then
  begin
    DoDownload(txtVideo.Text,SaveDialog1.FileName);
    showmessage('done');
  end;
end;

end.

ma quando lo eseguo ottengo l'errore "problems downloading url...": qualcuno sa dirmi perchè? grazie in anticipo per l'aiuto!

[alka]

Almeno dovresti indicarci qual è la riga in cui viene restituito l'errore, altrimenti siamo tutti costretti a prendere il codice, copiarlo ed eseguirlo, mentre forse è possibile risalire alla causa senza adottare questo procedimento semplicemente individuando qual è l'istruzione che solleva l'eccezione indicata.

[temporaryuser]

Ok scusa
l'errore lo ottengo qui

function DoDownload(vURL, vLocation : String): Boolean;
begin
  with TDownloadURL.Create(nil) do
  try
    URL:= vURL;
    FileName := vLocation;
    OnDownloadProgress := Form1.URL_OnDownloadProgress;
 -->  ExecuteTarget(nil) ; 
  finally
    Free;
  end;
end;

[alka]

Quanto è recente quel pezzo di codice? Lo chiedo perché a volte vengono apportate modifiche a YouTube e determinati indirizzi finiscono per non essere più attivi o validi.

[temporaryuser]

non saprei dirti, ma ho trovato su internet altre funzioni pressochè uguali (e funzionanti) per scaricare file html. Tu conosci qualche altro metodo per scaricare video con delphi?