Stock footage
Stock footage, and similarly, archive footage, library pictures, and file footage is film or video footage that can be used again in other films. Stock footage is beneficial to filmmakers as it saves shooting new material. A single piece of stock footage is called a "stock shot" or a "library shot". Stock footage may have appeared in previous productions but may also be outtakes or footage shot for previous productions and not used. Examples of stock footage that might be utilized are moving images of cities and landmarks, wildlife in their natural environments, and historical footage. Suppliers of  stock footage may be either rights managed or royalty-free. Many websites offer direct downloads of clips in various formats. History. Stock footage companies began to emerge in the mid-1980s, offering clips mastered on Betacam SP, VHS, and film formats. Many of the smaller libraries that specialized in niche topics such as extreme sports, technological or cultural collections were bought out by larger concerns such as Corbis or Getty Images over the next couple of decades. Films and television. Stock footage can be used to integrate news footage or notable figures into a film. For instance, the Academy Award-winning  film "Forrest Gump" used stock footage extensively, modified with computer-generated imagery to portray the lead character meeting such historic figures such as John F. Kennedy, Richard Nixon, and John Lennon. Television and movies series also often recycle footage taken from previous installments. For instance, the "Star Trek" franchise kept a large collection of starships, planets, backgrounds, and explosions, which would appear on a regular basis throughout Star Trek's five series and ten films, being used with minimal alteration. That kept production costs down as models, mattes, and explosions were expensive to create. The advances in computer graphics in  the late 1990s and early 2000s helped to significantly reduce the cost of Star Trek's production, and allowed for a much wider variety of shots than previous model and painting based visuals. Other films that re-used film footage from previous productions include "", "Blade Runner", "", "Hitman", "", "Halloween II", "Harry Potter and the Order of the Phoenix", "Harry Potter and the Deathly Hallows - Part 1 "& 2" and "Bill & Ted's Excellent Adventure". Some series, particularly those made for children, such as "Power Rangers" or "Teletubbies", reuse footage that is shown in many episodes. Meant for a young audience, the approach  increases viewers' familiarity between shows. This introduces problems such as the requirement to, for example, wear the same clothing and inconsistency can sometimes become a problem. When cleverly filmed it is possible to avoid many of these problems. Many broadcast shows use stock-footage clips as establishing shots of a particular city, which imply that the show is shot on location when in fact, it may be shot in a backlot studio. One or two establishing shots of an exotic location such as the Great Wall of China, Easter Island, or French Polynesia will save production companies the major costs  of transporting crew and equipment to those actual locations. Stock footage is often used in commercials when there is not enough money or time for production. More often than not these commercials are political or issue-oriented in nature. Sometimes it can be used to composite moving images that create the illusion of having on-camera performers appear to be on location. The term "B-roll" may refer to stock footage or newly shot scenes. Stock footage that appears on television screens or monitors shown in movies or television shows is referred to as "playback". In "", which was written by  and starring Will Ferrell as a San Diego news anchor, the studio purchased archival 1970s clips from San Diego stock footage firm New & Unique Videos. The playback footage of a hurricane featured in Disney's "Smart House" came from the vaults of the same San Diego firm. One of the most common uses of stock footage is in documentaries. Use of stock footage allows the filmmaker to tell the story of historical events such as World War II "Why We Fight" series, to document modern underwater archaeology activities, or to supplement content in natural history documentaries. Budgets may not be  sufficient to keep a production crew on site for long-term projects, and stock footage allows the producer to pick the moments in time that are most important to the story or to give context to historical events. Several films that would otherwise be completely lost have surviving footage due to the film being used as a stock footage. For example, "The Cat Creeps" has some scenes preserved in the movie "Boo", and scenes from "Queen of the Night Clubs" are preserved as stock footage in "Winner Take All". If not for the use of stock footage, these films would  be lost entirely. Stock Footage are also used in live reality TV shows such as "I'm a Celebrity". In recent months, stock footage of studio audience applause and reactions have been used in TV shows in place of a live studio audience due to the current COVID-19 crisis. Corporate usage. Companies throughout the world use stock footage in their video productions for in-house meetings, annual conventions, seminars, and other events. It has become popular to videotape interviews of CEOs and other VIPs using a green screen backdrop. When the green is keyed out during post-production, stock footage  or stock shots are inserted, to impart a particular message. Public domain. One of the largest producers of public domain stock footage is the United States government. All videos produced by the United States military, NASA, and other agencies are available for use as stock footage. There are a number of companies that own the copyrights to large libraries of stock footage and charge filmmakers a fee for using it, but they rarely demand royalties. Stock footage comes from a myriad of sources including the public domain, other movies and television programs, news outlets, and purpose-shot stock footage. Format . Evolution. With each introduction of new standard, it requires reshooting, rerendering, or rescanning the popular footage as well as new images to show the capabilities of the next standard. Betacam SP, VHS, and early digital footage was shot in standard-definition (SD), in 4:3 aspect ratio. Next came a higher resolution format, High Definition (HD), with a , which is closer to cinema widescreen formats. Many stock-footage companies and producers were concerned that their libraries would become irrelevant. Most stock footage companies & distributors now require HD 1080p footage at a minimum with many requesting 2K resolution and 4K  resolution raw footage. Many companies are also including Virtual Reality (VR) and 360-degree video footage. Container. Popular digital container formats include MOV (QuickTime File Format) AVI, FLV, MP4, and MXF, which are commonly used in non-linear editing system applications such as Avid, Final Cut Pro, and Adobe Premiere Pro. Libraries. Notable stock footage libraries and archives include: