Encyclopedia of Computer Science and Technology

194 film industry and computingImplementationsOnce the programs agree on the basic parameters for a filetransfer, the transfer has to be managed to ensure that itcompletes correctly. Typically, files are divided into blocksof data (such as 1K, or 1024 bytes each). During the 1970s,Ward Christensen developed Xmodem, the first widely usedfile transfer program for PCs running CP/M (and later, MS-DOS and other operating systems). Xmodem was quite reliablebecause it incorporated a checksum (and later, a moreadvanced CRC) to check the integrity of each data block.If an error is detected, the receiving program requests aretransmission.The Ymodem program adds the capability of specifyingand sending a batch of files. Zmodem, the latest in this lineof evolution, automatically adjusts for the amount of errorscaused by line conditions by changing the size of the datablocks used and also includes the ability to resume after aninterrupted file transfer. Another widely used file transferprotocol is Kermit, which has been implemented for virtuallyevery platform and operating system. Besides file transfer,Kermit software offers terminal emulation and scriptingcapabilities. However, despite their robustness and capability,Zmodem and Kermit have been largely supplanted bythe ubiquitous Web download link.In the UNIX world, the ftp (file transfer protocol) programhas been a reliable workhorse for almost 30 years.With ftp, the user at the PC or terminal connects to an ftpserver on the machine that has the desired files. A variety ofcommands are available for specifying the directory, listingthe files in the directory, specifying binary or text mode,and so on. While the traditional implementation uses typedtext commands, there are now many ftp clients available forPCs that use a graphical interface with menus and buttonsand allow files to be selected and dragged between the localand remote machines.Even though many files can now be downloaded throughHTML links on Web pages, ftp is still the most efficient wayto transfer batches of files, such as for uploading content toa Web server.Further Reading“FTP New User Guide.” Available online. URL: http://www.ftpplanet.com/ftpresources/basics.htm.Accessed August 4,2007.Loshin, Peter. Big Book of Internet File Transfer RFCs. San Diego,Calif.: Morgan Kaufmann, 2000.Pike, Mary Ann, and Noel Estabrook. Using FTP. Indianapolis:Que, 1995.“What Is Kermit?” Columbia University. Available online. URL:http://www.columbia.edu/kermit/kermit.html. AccessedAugust 4, 2007.film industry and computingAnyone who compares a science fiction film of the 1960s or1970s with a recent offering will be struck by the realism withwhich today’s movie robots, monsters, or aliens move againstvistas of giant starships and planetary surfaces. The computerhas both enhanced the management of cinematic productionprocesses and made possible new and startling effects.The role of the computer in film begins well beforethe first camera rolls. Writers can use computers to writescripts, while specialized programs can be used to layout storyboards. Using 3D programs somewhat like CAD(drafting) programs, set designers can experiment withthe positioning of objects before deciding on a final designand obtaining or creating the physical props. For mattes(backgrounds against which the characters will be shot ina scene), a computer-generated scene can now be inserteddirectly into the film without the need for an expensive,hand-painted backdrop.Similarly, animation and special effects can now be renderedin computer animation form and integrated into thestoryboard so that the issues of timing and combining ofeffects can be dealt with in the design stage. The actualeffects can then be created (such as by using extremelyrealistic computer-controlled puppets and models togetherwith computer generated imagery, or CGI) with the assurancethat they will properly fit into the overall sequence.The ability to combine physical modeling, precise control,and added textures and effects can now create a remarkablyseamless visual result in which the confrontation between abeleaguered scientist and a vicious velociraptor seems quitebelievable.Just as the physical and virtual worlds are frequentlyblended in modern moviemaking, the traditional categoriesof visual media have also merged. Disney’s fully animatedfilms such as The Lion King benefit from the same computergeneratedlighting and textures as the filming of live actors.Using 3D graphics engines, computer game scenes are nowrendered with almost cinematic quality (see computergames). Even characters from old movies can be digitallycombined (composited) with new footage. (Of course, theartistic value of such efforts may be controversial.)Computer technology, now relatively inexpensive, canalso give the generally lower budget world of televisionaccess to higher-quality effects. As computers continue tobecome more powerful yet cheaper, amateur or independentfilmmakers are gaining abilities previously reserved tobig Hollywood studios.The delivery of film and video has also been greatlyaffected by digitization. Classic movies can be digitizedto rescue them from deteriorating film stock, while videoscan be delivered digitally over cable TV systems or over theInternet. The ability to easily copy digital content does raiseissues of piracy or theft of intellectual property (see intellectualproperty and computing).More recently, digital camcorders (and video modes indigital cameras and even cell phones) are making access tobasic “film” technology a part of everyday life. A few minutesbrowsing a video-sharing site (see YouTube) revealsa wide variety of documentary and creative productionsranging from the equivalent of the old “home movie” toprofessional quality.Further ReadingHarris, Tom. “How Digital Cinema Works.” Available online. URL:http://entertainment.howstuffworks.com/digital-cinema.htm.Accessed August 4, 2007.