So Say We All

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I also finally finished dowloading a 5G torrent of the new Battlestar Galactica series, and subjected myself to a marathon while attempting to analyze the thing. I’m not totally confident in my analyses of what it’s trying to say, other than the superficial “robots with monotheistic religion bad, human civilians neutral, human soldiers and the Greek pantheon good, m’kay.”

Aside from political interpretations (torture is OK because they [who you can tell because they all look alike] are “evil killing machines”), I think it’s interesting that without being able to download a torrent of the series (which the enternaitnment industry has said it wishes to make illegal) I wouldn’t care, wouldn’t have spent 15 hours of my life watching their show, and wouldn’t blog about it. And as a result, the series wouldn’t get the free publicity, which means fewer fans, which means lower “associated junk” revenues (DVDs, merchandizing, etc.). So, as long as superficial analysis is in the cards, you can roughly translate this as “free == good”.

On a more technical note, I’m not familiar with bittorrent’s technical decisions, other than the fact it uses rar for it’s compression/archive format and can thus hold multiple files in a single torrent, but I do have a complaint. I’m not sure if this complaint is valid against all torrents, the specific torrent I downloaded, or the client I use, but it is still a complaint.

Whatever the cause, the fact that you really can’t do anything with the stuff that has been downloaded until the entire torrent is done sucks. Basically, even though it’s dumping multiple gigs of data on my disk, none of it is usable until the whole thing is done — even if the torrent’s contents are stream-capable (like most video or plain text files are). So it took me about a week of on/off downloading (fortunately gnome-bt has a stop button, but I was unwilling to try quitting the app to see if it can pick things up that way) to get the series, and I had to wait until all 5GB had been transfered before I could watch any of the stuff that was in it.

My other complaint is a trivial/asthetic one: It’d be nice if gnome-bt looked like the Nautilus file-transfer dialog and got rid of the upload and events tabs (IMO, it should automatically aim for a 1:1 ratio of upload to download, and while the “events” tab may be useful for debugging, it isn’t very useful for users — the extra prefs can be hidden).

14 thoughts on “So Say We All

  1. It’s client thing. I use mldonkey running on router to download torrents. mldonkey creates directory BT/ under ./temp/, where torrents are downloaded. If torrent is made of directory with files, you can enter to that directory and view files.

  2. As far as I understand it, it’s the warez community that uses rar, no BitTorrent. I’ve downloaded multi-file torrents that save each file individually so you can start watching the first part once it is done. It’s simply that for what ever reason, a lot of people putting together warez packages (especially with windows program from what I remember) but apparently now with movies/shows aswell, like using rar. It’s some kind of convention I guess.
    Windows: Zip
    Linux: .tar.gz .tar.bz2
    Warez: .rar
    Even though in this day and age each OS can handle all the archive types and a lot more, old habits die hard.

    As for the dialog, I agree, but is either one of us going to take the time to rewrite it? 🙂

  3. The use of rar depends only on who create the seed, if you have multiple files you can distribute them in a dir, and with some clients, you can choose to download only the files you need…

  4. Thomasz: Yeah, gnome-bt does the same thing (creates a directory that files are downloaded to), but the files themselves were unreadable (lots of binary junk) until the download had completed. I’m guessing it’s because of the rar compression (e.g. common AVI headers getting compressed once and tacked on the end of the file in question).

    Dan: Yeah, I’ve run into the rar crowd before, I’ve heard that it’s supposed to give better compression than .zip, and Windows users are mostly unfamiliar with gzip/bzip2 (part of it, I think, is that WinZip shows a .tar.gz as an archive within an archive for tar.gz files). And it wouldn’t be a rewrite of the dialog, so much as ripping out existing code :-).

    Andrea: Interesting…

  5. Whether you can use a file right away or not depends greatly on the format (and if it’s in a compressed file, like yours, that’s very unlikely). From what I remember, the BT protocol itself is the limiter – and also the reason why it’s so much faster.

    Data is chunked; you don’t necessarily get the chunks in order. Worst case, you could get n, n-1, … 0 – but since chunks come in random order, I’d doubt it. The chunking means that you can’t view a stream, because any sequence is purely by chance.

    So it’s faster because you can get the chunk from anyone, even a slow modem connection can contribute. Conceiveably, a T1 conection could be saturated by a large enough number of modem user sending data upstream if the chunks were small enough. I dunno for sure, I’m not an expert, but it’s an interesting thought.

    (I am interested in the show, can’t see it here, and haven’t been able to find a working torrent – care to point me in the right direction?)

  6. Another reason BitTorrent does what it does with not making the files available progressively is because the protocol asks for ranges pretty much randomly throughout the file, based on the list of clients given to it by the tracker and the associated information about which ranges those clients in turn have. This helps increase the overall efficiency of the network, but at the expense of being able to use part-downloaded files.

  7. Being able to control upload on BT is fairly essential for two reasons; making sure it doesn’t saturate your upstream is one, but the other is that the sizable and growing minority of people with ISP-imposed bandwidth caps need to be able to restrict it. I’d love to upload everything I download at 1:1 but my bandwidth cap is too small for me to do it. I’ll let the lucky people whose ISPs haven’t yet started to restrict bandwidth use handle the strain…

  8. Torrents that contain compressed files (eg. RAR) are usually a bad idea.

    First, most audio or video is already compressed, so they don’t really provide much of a space saving.

    Second, after downloading 5GB of compressed data you probably want to decompress it so you can watch it. Now you’ve got about 10GB on your disk (the compressed version and uncompressed version). If you delete the compressed version to save disk space, you can’t continue to provide upload bandwidth for the torrent, so it encourages people to leave a torrent sooner.

    If the data files are not compressed, they are usable and shareable at the same time.

  9. The reason you can’t use Bit Torrent files until they’re downloaded is that you don’t get the file in order. Clients either create sparse files or allocate files of just zeros and fill them in as the data is downloaded.

    It’s annoying, but it’s key reason why bit torrent works so well! Since the pieces are distributed essentially randomly, it means that even if no one on the network has the WHOLE file, we still might be able to assemble the file from our various parts.

    Furthermore, it means that the entire network is able to go faster. If the data was downloaded sequentially, and I have 56% of the file, that means I can only downloaded from peers that already have AT LEAST 56% of the file. With “random” part distribution, I can connect to any 20 users and odds are that I will be able to trade parts with all of them. So the number of people that I am able to download from has increased dramatically!

    In other words, random part distribution (rather than sequential downloading) is KEY to the bittorrent network. Yes, it’s annoying when you want to watch something Right Now, but it’s one of the main things that makes the entire protocol work so well.

  10. If BT would download chunks sequentially, everyone would have the first 5% of the torrent, but only the seeders would have the last 5%. This would mean that downloading the last few % of the torrent would take orders of magnitude longer. Also, you suggest that each client makes sure the upload/download ratio should always be 1. If you would read the design documents on how connections are established, you would understand that this would completely break a well thought out system that automatically finds and maintains links between computers that have a high internal bandwidth. The changes you are proposing to BT would make torrent perform as slowly as ftp.

    Two notes on your usage of BitTorrent:

    1). The more advanced clients allow you to selectively download only a subset of the files in a torrent. So if you are downloading a torrent for a season of a TV-series, you can make sure the program first downloads the first episode.

    2). Most, maybe even all BitTorrent client allow you to quit and later on resume the download.

  11. The warez community uses .rar at the best of times: be glad it’s not a self-extracting .exe inside a .zip inside a .rar, with liberal sprinklings of splittage.

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