Hack 86. Use BitTorrent to Distribute Your Video
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Use BitTorrent to Distribute Your Video Using BitTorrent, a peer-to-peer network application, you can have other people distribute your movie for you. Digital video files can be quite large. If you plan on distributing your movie online, you might wind up paying more than you expect, or you might even have your distribution stopped due to exceeding your bandwidth allocation. BitTorrent is a peer-to-peer (P2P) network application created by Bram Cohen. What sets BitTorrent apart from other P2P applications is the method it uses to distribute files. In most P2P applications, when you request to download a file, that file is obtained from only one machine. By downloading from one machine, you are limited to that machine's connection to the Internet, whether it is fast or slow, reliable or not. BitTorrent, in contrast, attempts to download a file from many machines at the same time. This torrent method allows people to obtain files both faster and more reliably, because the requested file is delivered in pieces. Some machines will have faster connections than others, but combined, they can all deliver a specific file faster than a single machine by itself. Additionally, the more popular a file is, the more quickly it can be distributed. BitTorrent uses .torrent files, which are usually small, to represent a complete file that exists in the network. Once someone has obtained a .torrent file, she can then download the complete file from the network. This is akin to browsing a movie rental store and taking the DVD cover to the front of the store so that the clerk can give you the actual DVD. Given the design of BitTorrent, it is a terrific method to distribute video files. To quote the BitTorrent web page: The key to cheap file distribution is to tap the unutilized upload capacity of your customers. It's free. Their contribution grows at the same rate as their demand, creating limitless scalability for a fixed cost. 7.12.1. Downloading a BitTorrent ClientThe official BitTorrent client is available for Windows, Mac OS X, and Linux and can be downloaded from the official BitTorrent web site at http:// bittorrent.com/download.html, but there are also many other BitTorrent clients available on the Internet. One client of particular interest is Azureus (http:// azureus.sourceforge.net; free), which includes a tracker (explained later) and is expandable through third-party plug-ins. Azureus is available for Windows, Mac OS X, and Linux. Installation instructions for all three operating systems are available on the Azureus web site. You need Java installed on your computer; download it for free from Sun (http:// www.java.com/en/download/manual.jsp). After installing Azureus, you're ready to download your first torrent. 7.12.2. Downloading a .torrent FileThere are essentially two steps to downloading a file using BitTorrent. The first is to obtain a .torrent file. The second is to open the .torrent file in yourBitTorrent client (in this case, Azureus), which begins downloading the specific file. To find .torrent files, you can use a BitTorrent tracker. A tracker keeps a list of available torrents and distributes the .torrent files required to obtain the complete files they represent.
Once you have located a tracker to use, simply select a file you would like to download. The file you get from the tracker should be a .torrent file. Using Azureus, open the torrent file and your download will proceed. Figure 7-40 shows a download in progress of movie called Panorama Ephera. Figure 7-40. Downloading a movie in Azureus
Depending on the size of the file you are downloading, your Internet speed, and the speed of the people who are sharing the file with you, your download might take some time to complete. You will more than likely want to work on something else while the download occurs perhaps something like creating a torrent of your own to share with the world! 7.12.3. Sharing a FileIf you want to make a file available in the BitTorrent network, you need to create a .torrent file. Unlike other P2P networks, which allow only one file, a .torrent file can be composed of many files. Most BitTorrent applications make this process painless, and Azureus is no exception. The easiest way to create a torrent and share a file is simply to choose File
Sharing a file this way both creates the .torrent file needed for your viewers to obtain the movie and adds the .torrent file to the built-in tracker. Figure 7-41 shows the Azureus BitTorrent Client Tracker in action, as someone downloads a file. Figure 7-41. Azureus enabling a viewer to download a movie People can access the tracker at http://your.host.name:6969. They can then download the .torrent file and load it into their BitTorrent client in order to download the actual movie. If you choose to, you can also download the file for yourself and then email it out to your friends, family, and groupies. 7.12.4. Using a Public Tracker.If you would prefer to use a public tracker to announce your file, you need to create a .torrent file for the tracker to use. Azureus makes creating such .torrent files easy. 7.12.4.1. Using the creation wizard.While running Azureus, choose File Figure 7-42. Creating a torrent file If you would like to have multiple trackers handle your .torrent file, check the appropriate checkbox. If you select this option, you will be able to add additional trackers in the following window.
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File…. Depending on the size of your movie, the process might take a while. During the process, a window will display the current status. Upon completion, the 
