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Thread: Downloading a video from youtube

  1. #1
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    Question Downloading a video from youtube

    Hi, what qt4 class could I use to download a video from youtube? I need to download a video from an url like this: http://youtube.com/get_video?video_i...xA5rvs=&fmt=18. Firefox download this video but Qhttp fails to download. Any suggestions?
    This is my code:
    Qt Code:
    1. QString video_url = "http://youtube.com/get_video";
    2. QString argument = "?video_id=Th7-EzW0Ccw&t=vjVQa1PpcFNQDXk1DXroxSYaUxdfZ23C8lngRxA5rvs=&fmt=18";
    3. QString dest = "/home/faster/video.mp4";
    4.  
    5. QUrl url(video_url);
    6. QFileInfo fileInfo(url.path());
    7. QString fileName = fileInfo.fileName();
    8. if (fileName.isEmpty())
    9. fileName = "index.html";
    10.  
    11. file = new QFile(dest);
    12.  
    13. QHttp::ConnectionMode mode = url.scheme().toLower() == "https" ? QHttp::ConnectionModeHttps : QHttp::ConnectionModeHttp;
    14. http->setHost(url.host(), mode, url.port() != -1 ? url.port() : 80);
    15.  
    16. if (!url.userName().isEmpty())
    17. http->setUser(url.userName(), url.password());
    18.  
    19. httpRequestAborted = false;
    20. QByteArray path = QUrl::toPercentEncoding(url.path(), "!$&'()*+,;=:@/");
    21. if (path.isEmpty())
    22. path = "/";
    23. httpGetId = http->get(video_url+argument, file);
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  2. #2
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    Default Re: Downloading a video from youtube

    Quote Originally Posted by Faster View Post
    Hi, what qt4 class could I use to download a video from youtube?
    There are many options.
    1. QHttp
    2. QTCPSocket
    3. QNetworkAccessManager
    4. QDesktopServices::openUrl();

  3. The following user says thank you to yogeshgokul for this useful post:

    Faster (28th November 2009)

  4. #3
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    Default Re: Downloading a video from youtube

    How can I download a video from http://youtube.com/get_video?video_i...xA5rvs=&fmt=18 using Qhttp? I posted my code but I don't understand what's wrong! It downloads a web page instead of the mp4 file.

  5. #4
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    Default Re: Downloading a video from youtube

    Quote Originally Posted by Faster View Post
    How can I download a video from http://youtube.com/get_video?video_i...xA5rvs=&fmt=18 using Qhttp?
    You need to call QHttp::get() with appropriate URL.

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    Default Re: Downloading a video from youtube

    I used this:
    Qt Code:
    1. http->get("http://youtube.com/get_video?video_id=Th7-EzW0Ccw&t=vjVQa1PpcFNQDXk1DXroxSYaUxdfZ23C8lngRxA5rvs=&fmt=18", file);
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    But it downloads only a web page and not the video file. If I open this link with firefox it downloads the correct video file. Any idea?

  7. #6
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    Default Re: Downloading a video from youtube

    Its downloading what youtube is sending. You need to parse the downloaded web page most likely.

  8. #7
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    Default Re: Downloading a video from youtube

    This is the web page content:

    Qt Code:
    1. Moved Permanently
    2. The document has moved here.
    3.  
    4. Apache Server at www.youtube.com Port 80
    To copy to clipboard, switch view to plain text mode 

    I'm creating a program that allows the user to download a video from youtube. I written a code that generates a link to a mp4 file using http://youtube.com/get_video. The link generated is session-sensitive and changed every time the video is accessed. This url works with web browsers but doesn't work with my program.
    Now I think that this url works only with web browsers. if my argumentation is right, how can I modify my code to make youtube believe that my program is a web browser, using qhttp?

    Sorry for my poor English. I hope I explained myself.

  9. #8
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    Default Re: Downloading a video from youtube

    Like I said before, you need to parse the returned content and process it. If a web browser receives "Moved Permanently The document has moved here.", then they will automatically follow that redirection. This is invisible to the user - they never see the message.

  10. #9
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    Default Re: Downloading a video from youtube

    No, the web browser receives the correct video while qhttp receives a redirection web page! The redirection link contained in this web page is the same link that I have used to download the page!

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    Default Re: Downloading a video from youtube

    When I follow the link you pasted using the browser, I get a blank page.
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.


  12. #11
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    Default Re: Downloading a video from youtube

    It doesn't work for me either. Maybe when Faster posts a link that works, we can help him

  13. #12
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    Default Re: Downloading a video from youtube

    The link doesn't work because is session-sensitive. Here I told that I have written a code that generates a link to download an mp4 file from youtube. So i can't post a link that works! The problem is that I can download this video with Firefox but not with qhttp!

  14. #13
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    Default Re: Downloading a video from youtube

    Maybe the reason is that you are logged in to youtube in firefox and not when using QHttp?
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.


  15. #14
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    Default Re: Downloading a video from youtube

    I'm not logged to youtube with firefox! I also tried to download the generated link with the qt4's http example (in examples/network/http) but this program downloads the same redirection page and not the video!

  16. #15
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    Default Re: Downloading a video from youtube

    Why don't you take a network sniffer and compare the traffic that goes from firefox to youtube and from your application to youtube and tell us what the difference is? Right now we're trying to guess some reasons with you only telling us "it works with firefox". We already know that, you don't have to repeat yourself. Or give us a working download link or tell us how to get one.
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.


  17. #16
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    Default Re: Downloading a video from youtube

    Quote Originally Posted by Faster View Post
    The link doesn't work because is session-sensitive. Here I told that I have written a code that generates a link to download an mp4 file from youtube. So i can't post a link that works!
    Fine, ok. Instead of posting a working link, post the code to your program that creates a working link so we can create our own (and what was the point of posting the link in your first message if you knew it wouldn't work for anyone else?)

    You may also wish to delete all off-line data from your browser, or maybe even install a different browser to check if your link works there. You may find it doesn't work until you have visited and logged into the site.

  18. #17
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    Default Re: Downloading a video from youtube

    I'm posting my current project! This program generates a link to download a video from youtube that works. Click on the "Start download" and paste the generated url on a browser. The url should work!

    The link work also with other browsers!
    Attached Files Attached Files
    Last edited by Faster; 27th November 2009 at 21:38.

  19. #18
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    Default Re: Downloading a video from youtube

    Ok, I've tried it. The browser downloads the mp4 file.

    HOWEVER, The browser gets a redirect page exactly the same as your program does. In fact, it gets two:

    http://youtube.com/get_video?video_id=...
    REDIRECTED TO: http://www.youtube.com/get_video?video...
    REDIRECTED TO: http://v15.lscache4.c.youtube.com/...

    Which makes perfect sense. You request a video, and the server redirects your browser to the least loaded server to provide you with that video.

  20. The following user says thank you to squidge for this useful post:

    Faster (28th November 2009)

  21. #19
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    Default Re: Downloading a video from youtube

    Which also means that if you used QNetworkAccessManager, you would probably instantly get the proper output - as far as I remember QNetworkAccessManager handles redirects by itself. If not, you need to handle them yourself.
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.


  22. #20
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    Default Re: Downloading a video from youtube

    Thanks a lot fatjuicymole and wysota! I don't understand how redirects works so I don't know how I can modify my program to manage redirects with qhttp... If QNetworkAccessManager handles redirects by itself, where can I find some examples about downloading with QNetworkAccessManager?

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