I downloaded some mkv/mp4 files with my new router (I can download directly from it, using transmission), and all of them seem to be corrupted: lags, strange artifacts when using vlc, crashes with mp4, etc.
Download the exact same torrent or magnet and reload it in uTorrent. Make sure to keep the directory same as the previous one. Once you start downloading, uTorrent will automatically re-check and start the download from the same spot. That said, we know that the best torrent site is always the one that has the high-quality torrent you're after, and with the most seeders, so a large and thorough list of torrent sites, like those in the list below the top torrents, is always a welcome resource to find.
When a downloaded part is corrupted, transmission warns you and downloads that part again. My question is: even after the transmission verification, is it possible that the downloaded file is still corrupt?
3 Answers
Yes, it is possible (although it might depend on the torrent client).
When I was having hard disk issues, my torrent client (Deluge) used to report files as downloaded 100%, when some parts of them were actually faulty. A forced re-check fixed that.
My educated guess is that the client downloaded the piece, checked it while it was stored in the RAM and then saved it to the hard drive (which makes sense having performance in mind). Something must have gone wrong while writing the data to the drive, thus corrupting the files.
If you force a re-check and the files still appear to be OK, chances are that it was a bad torrent or you have issues with your computer. A hash collision is theoretically possible, but highly unlikely in practice.
DennisDennisAbsolutely. It is already possible to generate colliding data, the only stipulation is that it has to be the same size as a block.
Ignacio Vazquez-Abrams
Ignacio Vazquez-AbramsHow To Download Torrent File
Saving data from RAM to disk is not error prone in any way. Only if there is a power problem or a serious disk issue which would be noticed very early due to errors in the OS.
Torrent poisoning is the only reliable answer I found so far.
Torrent poisoning is intentionally sharing corrupt data or data with misleading file names using the ?BitTorrent protocol. This practice of uploading fake torrents is sometimes carried out by anti-piracy organisations as an attempt to prevent the peer-to-peer (P2P) sharing of copyrighted content, and to gather the IP addresses of downloaders.
Source: http://en.wikipedia.org/wiki/Torrent_poisoning
Not the answer you're looking for? Browse other questions tagged bittorrentchecksum or ask your own question.
BitTorrent networking is the most popular form of modern P2P (peer-to-peer) file sharing. For years, BitTorrent sharing has been the primary means for users to trade software, music, movies, and digital books online. Torrents are very unpopular with the MPAA, the RIAA, and other copyright authorities, but are much beloved by millions of others around the world.
BitTorrent (commonly just called 'torrent') is a communication protocol much like HTTP and FTP. However, while all three are used to transfer files over a network, BitTorrent works by downloading small bits of files from many different web sources at the same time.
Despite the complexity of how BitTorrent works, torrent downloading is actually very easy to do, and outside of a few torrent search providers, torrents themselves are completely free to use.
How Torrents Are Special
Like the other file-sharing networks (Gnutella, eDonkey, etc.) BitTorrent's primary purpose is to distribute large media files to private users. Unlike most P2P networks, however, torrents stand out in a few major ways:
Torrent networking isn't a publish-subscribe model like Kazaa; instead, torrents are true peer-to-peer networking where the users themselves do the actual file serving.
Torrents enforce 99 percent quality control by filtering out corrupted and dummy files, ensuring that downloads contain only what they claim to contain. There's still some abuse of the system, but if you use a community torrent searcher, users will warn you when a torrent is a fake.
Torrents actively encourage users to share (seed) their complete files, while simultaneously penalizing users who download but don't share (leech).
Torrent code is open-source, advertising-free, and adware/spyware-free. This means that no single person profits from torrent success.
How BitTorrent Sharing Works
Torrent sharing is all about 'swarming and tracking,' where users download many small bits from many different sources at once. Because this format compensates for bottleneck points, it is actually faster than downloading a large file from a single source.
- Swarming involves splitting large files into hundreds of smaller bits and then sharing those bits across a 'swarm' of dozens of linked users.
- Tracking is when specific servers help swarm users find each other.
- Swarm members use special torrent client software to upload, download, and reconstruct the many file bits into complete usable files.
- Special .TORRENT text files act as pointers during this whole process, helping users find other users to swarm with, and enforcing quality control on all shared files.
Torrent users voluntarily upload their file bits to their swarm without payment or advertising revenue. You could say torrent users are motivated not by money but by a 'Pay-It-Forward' cooperative spirit. Like the Napster model of the 1990s, BitTorrent swarming is the same, but with sharing incentive added.
Download speed is controlled by torrent tracking servers who monitor all swarm users. If you share, tracker servers will reward you by increasing your allotted swarm bandwidth. Similarly, if you leech and limit your upload sharing, tracking servers will choke your download speeds, sometimes to as slow as 1 kilobit per second. Indeed, the 'Pay It Forward' philosophy is digitally enforced! Leeches are not welcome in a BitTorrent swarm.
What You Need for Torrenting
BitTorrent swarming requires six major ingredients:
- BitTorrent client software
- A tracker server (hundreds of them exist on the web, no cost to use)
- TORRENT file that points to the file (song, movie, etc.) you want to download
- A torrent search engine that helps you find TORRENT files
- A decent internet connection, possibly with a special port open on the router to allow for torrent file trading
- A general understanding of file management on your computer. You'll need to navigate several folders and files to make file sharing work for you
At the very worst, it might take you about one day to set up your computer for torrent swarming, much less if your firewall program is set up properly to allow for BitTorrent traffic.
Something else you might run into are NAT error messages if your router hasn't been set up to forward the correct port to your computer. Different torrent clients use different ports, and some even let you choose which port to use, but 6881 is common.
How to Download Torrents
Accessing torrent files and using them to download songs, movies, etc., is extremely straightforward because most programs that use torrent files make the entire process super easy to follow.
Torrenting is not legal in all countries, and even in the ones where you can torrent legally, it doesn't mean that all torrents you find online are legal! That might sound confusing, but really all you need to know is that although the act of using torrents might be legal where you live, it doesn't mean that every file you can get through a torrent is equally legal. Sharing most software, music, and movies violate copyright laws and should be avoided.
Choose a torrent program to use for downloading torrents. Through that link are both software programs that install to your computer and online torrent clients that run from a browser. Either will work just fine.
Use a torrent website to locate the torrent you want to download.
Download the torrent file to your computer by selecting it and then choosing where on your computer to save it. Or, if the torrent site has an option for a magnet link, copy it like you would any URL.
Open the torrent file in the torrent program you downloaded earlier.
If the program is running on your computer, you can most likely just open the .TORRENT file and it will automatically load into the torrent client. If you're using an online torrent client, find an option for uploading the torrent file or a place where you can paste a magnet link.
Run your torrent downloads before going to bed so that you can fully download the data and even spend a couple hours seeding for others. It's also recommended to download torrents when you're not using your computer so that other network activity doesn't affect the bandwidth you need for torrents.
Wait while the torrent program talks to a tracker server to find users from which you can download the file(s) you're after.
As the tracker locates torrent users to swarm with, each user will be labeled as either a leech/peer (they have only a part of the file) or as a seed (they have the complete file you're trying to download). Depending on the torrent client you use, you may or may not see these details.
As you might guess, the more seeds you connect to, the faster your download will be. Usually, 10 peers/leeches and three seeders is a good swarm for downloading a large file. If the download doesn't start for a while, return to Step 2 and try finding a torrent with a higher seed count.
Wait while the torrent client finishes the file transfer, or download the file to your computer when it's finished if you're using an online torrent client. As 'sharing' implies, every transfer will happen in both directions, “down” and “up” (leech and share).
What to Do After Downloading Torrents
Keep your torrent client running for a few hours to give other users the opportunity to download from you. It's recommended to seed the data yourself now that you have it, so that other users who try downloading the same torrent can get the file(s) more quickly.
Technically, this isn't required — you won't get banned from the internet or lose your downloaded file. While it's true that uploading lots of data can negatively affect your own network performance, seeding is definitely considered friendly and helpful. After all, you most likely downloaded the torrent from other seeders, so it wouldn't hurt to return the favor and be one yourself for a few hours.
You might need to download specific software to open the files you downloaded from the torrent. This might include codec packs, converter software, or media player plug-ins. However, if it's music or movies you've downloaded, consider using VLC which supports lots of different media file formats.
Something else to consider if you plan to use torrents a lot is an extra hard drive just for those files. Downloading games, movies, music collections, images, etc., can add up quickly, so using an external hard drive, a secondary internal one, or even a flash drive can be helpful.
Other Ways to Share and Download Files
Not all online file sharing is done through BitTorrent. You might want to avoid BitTorrent if torrenting is illegal where you live or if the entire process just isn't appealing to you. Or maybe you can't find what you want to download from a torrent.
For example, another way to get free movies without using torrents is with a movie streaming service. Few of them let you download movies for free but even if you can only stream, you get to legally watch the movies and TV shows absolutely free.
The same idea is true behind free music streaming services and websites that let you download audiobooks. While you can get music and audiobooks from a torrent, too, it's much more likely that you'll stumble on something illegal by accident, whereas established file sharing services are known to be legal.
There are also other ways to share files online. For starters, email and text messages are simple and straightforward file sharing methods, but they do have severe limitations when big files are involved. On the other hand, they're really easy to use and nearly everyone has access to them.
One way to send large files online is with a cloud storage service. The downfall with this method is that it's not ideal if you're looking for a decentralized, P2P sharing method since the files are stored online.
How To Download Movie Torrent
An example of a free P2P service that runs in your web browser is ShareDrop. It's a tool that lets you share files anonymously with anyone, no matter how large the files are or where the users are from.