Camcorder
From Wikipedia, the free encyclopedia
A camcorder is a portable electronic device for recording video images and audio onto an internal storage device. The camcorder contains both a video camera and (traditionally) a videocassette recorder in one unit, hence its portmanteau name. This compares to previous technology where they would be separate.
The earliest camcorders, developed by companies such as JVC, Sony, and Kodak, used analog videotape, but since the mid-1990s (and even before that in professional markets), camcorders recording digital video have become the norm.
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[edit] History
Video cameras were originally designed for broadcasting television images — see television camera. Cameras found in television broadcast centres were extremely large, mounted on special trolleys, and wired to remote recorders located in separate rooms. As technology advanced, miniaturization eventually enabled the construction of portable video-cameras and portable video-recorders.
Prior to the introduction of the camcorder, portable video-recording required two separate devices: a video-camera and a VCR. Specialized models of both the camera and VCR were used for mobile work. The portable VCR consisted of the cassette player/recorder unit, and a television tuner unit. The cassette unit could be detached and carried with the user for video recording. While the camera itself could be quite compact, the fact that a separate VCR had to be carried generally made on-location shooting a two-person job.
In 1982, Sony released the first professional camcorder named "BETACAM". BETACAM was developed as a standard for professional camcorders. At first, cameramen didn't welcome BETACAM, because before BETACAM, carrying and operating the VCR unit was a work of a video engineer, after BETACAM, they came to be required to operate both video camera and VCR. However, the cable between cameramen and video engineers was eliminated. For this reason, the freedom of cameramen has improved dramatically and BETACAM became standard.
In 1983, Sony released Betamovie for consumers, the first domestic camcorder. A novel technique was used to reduce the size of the spinning video head drum, which was then used for many subsequent camcorders. The unit was bulky by today's standards, and since it could not be held in one hand, was typically used on resting on a shoulder. Some later camcorders were even larger, because the Betamovie models had only optical viewfinders and no playback or rewind capability. Most camcorders were and still are designed for right-handed operation, though a few possessed ambidextrous ergonomics.
Within a few years, manufacturers introduced two new tape formats tailored to the application of portable-video: the VHS-C format and the competing 8mm. VHS-C was essentially VHS with a reduced-size cassette. The VHS-C cassette held enough tape to record 30 minutes of VHS video, while a mechanical adapter enabled playback of VHS-C videocassettes in standard (full-size) VHS VCRs. VHS-C allowed manufacturers to reduce the weight and size of VHS-derived camcorders, although at the expense of recording time. The alternative 8 mm video on the other hand radically reduced the size of camcorders without the problem of short running time, by using an all-new metal composition video cassette. 8 mm video used a tape whose width is 33% less than VHS/Betamax tape (~12.7 mm), allowing even further miniaturization in the recorder's tape-transport assembly and cassette media.
8mm video represented a trade-off for the consumer. On the plus side, the 8mm camcorder generally produced higher quality recordings than a VHS/VHS-C camcorder, and the standard 8mm cassette could record up to two hours. On the down side, since the 8mm format was incompatible with VHS, 8mm recordings could not be played in VHS VCRs. In most cases, viewers would connect the camcorder to their home VCR, and copy their recordings on to a VHS tape.
The dominance of VHS among TV-timeshifters and rental-audiences guaranteed VHS-C an uneasy coexistence alongside 8mm. Serious amateur-videographers preferred 8mm, simply because it was better suited (than VHS/VHS-C) for the task of video production. But some casual and family users preferred VHS-C because of its shared lineage (and familiarity) with VHS. Equally important, entry-level VHS-C camcorders were priced less than 8 mm units. During the 1990s, the UK market saw Video8 and Hi8 eat into VHS-C/S-VHS-C sales as manufacturers such as Sharp Corporation dropped their VHS-C models in favour of 8mm. Eventually the only major manufacturers marketing VHS-C were JVC and Panasonic, so the format fell into obsolescence.
Throughout the 1990s, camcorder sales had the unintended side-effect of hurting the still camera photography market. [citation needed] Among the mass consumer market, camcorders gradually replaced still cameras for vacation and travel use. [citation needed] All Camcorders had a built in microphone, even though in the 1990s the use of a uni-directional microphone provided a more professional sound quality. Most analog-format camcorders traditionally had a single microphone, providing monophonic sound; it was only with the rise of digital camcorders that stereo microphones became common, and some DVD-based camcorders even include surround sound capability.
In the late 1990s, the camcorder reached the digital era with the introduction of miniDV. Its cassette media was even smaller than 8 mm media, allowing another size reduction of the tape transport assembly. The digital nature of miniDV also improved audio and video quality over the best of the analog consumer camcorders (SVHS-C, Hi8.) Variations on the digital-video camcorder included the Digital8 camcorder, and the DVD camcorder.
The evolution of the camcorder has seen the growth of the camcorder market as price reductions and size reductions make the technology more accessible to a wider audience. When camcorders were first introduced, they were bulky shoulder-operated luggables that cost over $1,500 US dollars. As of 2006, an entry-level MiniDV camcorder fits in the palm of a person's hand, at a price under $300 US dollars.
[edit] Overview
[edit] Major components
Camcorders contain 3 major components: lens, imager, and recorder. The lens gathers and focuses light on the imager. The imager (usually a CCD or CMOS sensor on modern camcorders; earlier examples often used vidicon tubes) converts incident light into an electrical (video) signal. Finally, the recorder encodes the video signal into a storable form. More commonly, the optics and imager are referred to as the camera section.
The lens is the first component in the camera-section's "light-path". The camcorder's optics generally have one or more of the following adjustments: aperture (to control the amount of light), zoom (to control the field-of-view), and shutter speed (to capture continuous motion.) In consumer units, these adjustments are automatically controlled by the camcorder's electronics, generally to maintain constant exposure onto the imager. Professional units offer direct user control of all major optical functions (aperture, shutter-speed, focus, etc.)
The imager section is the eye of the camcorder, housing a photosensitive device(s). The imager converts light into an electronic video-signal through an elaborate electronic process. The camera lens projects an image onto the imager surface, exposing the photosensitive array to light. The light exposure is converted into electrical charge. At the end of the timed exposure, the imager converts the accumulated charge into a continuous analog voltage at the imager's output terminals. After scan-out is complete, the photosites are reset to start the exposure-process for the next video frame. In modern (digital) camcorders, an analog-to-digital (ADC) converter digitizes the imager (analog) waveform output into a discrete digital-video signal.
The third section, the recorder, is responsible for writing the video-signal onto a recording medium (such as magnetic videotape.) The record function involves many signal-processing steps, and historically, the recording-process introduced some distortion and noise into the stored video, such that playback of the stored-signal may not retain the same characteristics/detail as the live video feed.
All but the most primitive camcorders imaginable also need to have a recorder-controlling section which allows the user to control the camcorder, switch the recorder into playback mode for reviewing the recorded footage and an image control section which controls exposure, focus and white-balance.
The image recorded need not be limited to what appeared in the viewfinder. For documentation of events, such as used by police, the field of view overlays such things as the time and date of the recording along the top and bottom of the image. Such things as the police car or constable to which the recorder has been allotted may also appear; also the speed of the car at the time of recording. Compass direction at time of recording and geographical coordinates may also be possible. These are not kept to world-standard fields; "month/day/year" may be seen, as well as "day/month/year", besides the ISO standard "year-month-day". And the Danish police have the speed of the police car in the units "Km/t" sic (time being Danish for "hour").
[edit] Consumer camcorders
[edit] Analog vs. digital
Camcorders are often classified by their storage device: VHS, Betamax, Video8 are examples of older, videotape-based camcorders which record video in analog form. Newer camcorders include Digital8, miniDV, DVD, Hard drive and solid-state (flash) semiconductor memory, which all record video in digital form. (Please see the digital video page for details.) The imager-chip is considered an analog component, so the digital namesake is in reference to the camcorder's processing and recording of the video.
The highest-quality digital formats, such as MiniDV and Digital Betacam, have the advantage over analog of suffering very little generation loss in recording, dubbing, and editing (MPEG-2 and MPEG-4 do suffer from generation loss in the editing process only). Whereas noise and bandwidth issues relating to cables, amplifiers, and mixers can greatly affect analog recordings, such problems are minimal or non-existent in digital formats using digital connections (generally IEEE 1394, SDI/SDTI, or HDMI). Both analog and digital can suffer from archival problems. Theoretically digital information can be stored indefinitely with zero deterioration on a digital storage device (such as a hard drive), but other types of media can have problems. Both analog and digital tape formats are prone deterioration over time. Digital recordings on DVD are known to suffer from DVD rot. The one advantage analog seems to have in this respect is that an analog recording may be "usable" even after the media it is stored on has suffered severe deterioration whereas it has been noticed[1] that even slight media degradation in digital recordings may cause them to suffer from an "all or nothing" failure, i.e. the digital recording will end up being totally un-playable without very expensive restoration work.
[edit] Modern recording media
For more information, see tapeless camcorder.
Some recent camcorders record video on flash memory devices (in MPEG-1, MPEG-2 or MPEG-4), Microdrives, small hard disks or size-reduced DVD-RAM or DVD-Rs in MPEG-2 format - but due to the limited size of the recording medium, their uninterrupted recording time is limited, and editing is difficult due to limitations of the data formats.
All other digital consumer camcorders record in DV or HDV format on tape and transfer content over FireWire (some also use USB 2.0) to a computer, where the huge files (for DV, 1GB for 4 to 4.6 minutes in PAL/NTSC resolutions) can be edited, converted, and (with many camcorders) also played back to tape. The transfer is done in real time, so the complete transfer of a 60 minute tape needs one hour to transfer and about 14GB disk space for the raw footage only - excluding any space needed for render files, and other media. Time spent in post-production (editing) to select and cut the best shots varies from instantaneous "magic" movies to hours of tedious selection, arrangement and rendering.
[edit] Consumer market
As the mainstream consumer market favors ease of use, portability, and price, consumer camcorders emphasize these features more than raw technical performance. For example, good low-light capabilities require large capturing chips, which affects price and size. Thus, consumer camcorders are often unable to shoot useful footage in dim light (though some units, particularly single-chip units by Sony, offer night vision capability). Manual controls need space, either in menus or as buttons and make the use more complicated, which goes against the requirement of ease of use. Consumer units offer a plethora of I/O options (IEEE 1394/Firewire, USB 2.0, Composite and S-Video), but lack many manual settings, often excluding video exposure, gain control, or sound level management. For the beginner, entry-level camcorders offer basic recording and playback capability.
For the sophisticated hobbyist (prosumer), high-end units offer improved optical and video performance through multi-CCD components and name-brand optics, manual control of camera exposure, and more, but even consumer camcorders which are sold for $1000 such as the Panasonic GS250 are not well-suited for recording in dim light. When dimly-lit areas are brightened in-camera or in post-production, considerable noise distracts the viewer.
Before the 21st century, consumer video editing was a difficult task requiring a minimum of two recorders. Now, however, a contemporary Personal Computer of even modest power can perform digital video editing with low-cost editing software. Many consumer camcorders bundle a light (feature-limited) version of such software, as do some computers, and more advanced software is widely available at a variety of price points.
As of 2006, analog camcorders are still available but not widely marketed anymore; those that are still available are often less than US$250, but require special capture hardware for non-linear editing. In terms of sales, miniDV camcorders (and to a much lesser extent, Digital8) dominate most first world markets. Camcorders which record directly on DVD media are also on the rise, primarily among users with no plans to edit their footage.
Hard disk based camcorders are appearing as well; JVC and Sony are the primary manufacturers of these units. Increased storage capacity over other types of media is the main advantage with these models; however, with this follows a slightly reduced image quality and loss of flexibility when compared to other formats such as MiniDV, making the ease of transferring the footage to a PC for quick editing the main attraction of Hard disk camcorders.
[edit] Other devices with video-capture capability
Video-capture capability is now available in selected models of cellphones, digicams, and other portable consumer electronic devices such as media players. Typically only digital cameras offer videos that are of useful quality for anything other than a novelty. The marketing approach is to claim 320 X 240 video is "VHS quality," and 640 X 480 video is "DVD quality." A few cameras can offer 800 X 600 resolution, and a recent development is High Definition (720p) in cameras such as the Sanyo Xacti HD1.
All are limited somewhat by having to serve as both cameras and camcorders. Compared to a dedicated camcorder they have poor low light performance, limited options, and many do not offer zoom during filming. (This is because the noise from the zooming motor is heard on the clip, only a few digicams have a manual zoom.) Many either have fixed focus lenses, or autofocus lenses that are sluggish and noisy compared to a camcorder.
The quality varies widely depending on the compression format used and the type of device. Frame rates can range from 30 FPS down to 10 FPS, or can be variable, slowing down in dark settings. The length of clips can also vary from "unlimited" (up to the capacity of the storage media) down to a few minutes.
Low end MPEG-4 camcorders can often record unlimited length video clips at 320 X 240, but the quality is far below even a VHS-C camcorder. In addition, MPEG-4 is currently not widely supported in many video editing programs. Cameras recording in Quicktime format produce videos of acceptable quality, but the compression appears as a grain or static in the video. Some cameras can offer exceptionally good video quality using the MJPEG codec, but the files are so large the recording time at high quality with a 1GB card is under ten minutes.
The use of digicams for recording video clips is limited mainly to circumstances where quality is not an issue. This is gradually being offset by the greater sophistication of the cameras, the increasing storage capacity of flash cards and microdrives, and the desire of consumers to carry only a single device.
[edit] Uses
[edit] Media
Camcorders have found use in nearly all corners of electronic media, from electronic news organizations to TV/current-affairs productions. In locations away from a distribution infrastructure, camcorders are invaluable for initial video acquisition. Subsequently, the video is transmitted electronically to a studio/production center for broadcast. Scheduled events such as official press conferences, where a video infrastructure is readily available or can be feasibly deployed in advance, are still covered by studio-type video cameras (tethered to "production trucks.")
[edit] Home video
For casual use, camcorders often cover weddings, birthdays, graduation ceremonies, and other personal events. The rise of the consumer camcorder in the mid to late '80s led to the creation of shows such as the long-running America's Funniest Home Videos, where people could showcase homemade video footage.
[edit] Politics
Political protestors have capitalized on the value of media coverage use camcorders to film things they believe to be unjust. Animal rights protestors who break into factory farms and animal testing labs use camcorders to film the conditions the animals are living in. Anti-hunting protestors film fox hunts. Anti-globalization protestors film the police to deter police brutality. If the police do use violence there will be evidence on video. Greenpeace uses camcorders to film their activities. Activist videos often appear on Indymedia.
The police use camcorders to film riots, protests and the crowds at sporting events. The film can be used to spot and pick out troublemakers, who can then be prosecuted in court.
[edit] Entertainment and movies
Camcorders are often used in the production of low-budget TV shows where the production crew does not have access to more professional equipment. There are even examples of Hollywood movies shot entirely on consumer camcorder equipment (see Blair Witch Project and 28 Days Later). In addition, many academic filmmaking programs have switched from 16mm film to digital video, due to the vastly reduced expense and ease of editing of the digital medium as well as the increasing scarcity of film stock and equipment. Some camcorder manufacturers cater to this market, particularly Canon and Panasonic, who both support "24p" (24 fps, progressive scan; same frame rate as standard cinema film) video in some of their high-end models for easy film conversion.
Even high-budget cinema is done using camcorders in some cases; George Lucas used Sony CineAlta camcorders (based on the XDCAM HD standard, and recording to ProDATA discs) in two of his three Star Wars prequel movies. This process is referred to as digital film.
[edit] Voyeurism
Camcorders can be used for voyeurism. In one of the most famous examples, Japanese television performer Masashi Tashiro was caught for taking a sneak shot of a woman's skirt (known as upskirt), in a commuter train station. When reporters asked why he had done it, he explained, "I tried to make a gag called "An octopus appears in a miniskirt" (Mini ni Tako ga Dekiru, ミニにタコができる)".
[edit] Formats
The following list covers consumer equipment only. (For other formats see Videotape)
[edit] Analog
- VHS: compatible with standard VCRs, though full-sized VHS camcorders are no longer made. Largely obsolete as a production medium.
- VHS-C: Designed for compact consumer camcorders; identical in quality to VHS.
- S-VHS: Largely used in high-end consumer and professional equipment; rare among mainstream consumer equipment, and obsoleted by digital gear.
- S-VHS-C: Designed for consumer equipment; currently available only on ultra-low-end equipment.
- Betamax: Only used on very old Sony camcorders; obsolete by the mid-80s in the consumer market although it continues to be used by professionals in the form of Betacam.
- Video8: small-format tape developed by Sony; equivalent to or slightly better than VHS, but not compatible. Obsolete.
- Hi8: Enhanced-quality Video8; originally used for professional field production, but now limited to ultra-low-end consumer market.
[edit] Digital
- Digital Tapeless: Low-end digital tapeless systems often use an MPEG-4 codec and flash memory; high-end versions, on the other hand, store video data to hard disk or optical disc.
- DV codec based:
- MiniDV and several derivatives, including DVCPRO from Panasonic and DVCAM from Sony. DV records the highest quality pictures (generally agreed to be at or near broadcast-quality) on DV tapes that are easily transferable via Firewire or USB to personal computers. Though designed as a consumer standard, there is extensive use of MiniDV in low-budget film and television production.
- Digital8, that uses Hi8 tapes (Sony is the only company currently producing D8 camcorders, though Hitachi used to). Some models of Digital 8 cameras have the ability to read older Hi8 analog format tapes. Though theoretically capable of the same quality as MiniDV, in practice most Digital8 equipment has been mid- to low-end consumer equipment, with virtually no demand in professional settings.
- MPEG-2 codec based:
- MICROMV: Uses a matchbox-sized cassette. Sony was the only electronics manufacturer for this format, and editing software was proprietary to Sony and only available on Microsoft Windows; however, open source programmers did manage to create capture software for Linux[2]. The hardware is no longer in production, though tapes are still available through Sony.
- DVD (with the biggest market increases): Uses either Mini DVD-R or DVD-RAM. This is a multi-manufacturer standard that uses 8 cm DVD discs for 30 minutes of video. DVD-R can be played on consumer DVD players but cannot be added to or recorded over once finalized for viewing. DVD-RAM can be added to and/or recorded over, but cannot be played on many consumer DVD players, and costs a lot more than other types of DVD recordable media. The DVD-RW is another option allowing the user to re-record, but only records sequentially and must be finalized for viewing. The discs do cost more than the DVD-R format, which only records once. DVD discs are also very vulnerable to scratches. DVD camcorders are generally not designed to connect to computers for editing purposes, though some high-end DVD units do record surround sound, a feature not standard with DV equipment.
[edit] Digital camcorders and operating systems
Since most manufacturers focus their support on Windows and Mac users, users of other operating systems often are unable to receive support for these devices. However, open source products such as Cinelerra and Kino (written for the Linux operating system) do allow full editing of some digital formats on alternative operating systems, and software to edit DV streams in particular is available on most platforms.
Many low-end tapeless camcorders, however, do not support any operating system but Windows, requiring either third-party software or a switch to a more standardized format such as DV.
[edit] See also
- Movie camera
- PictBridge
- PXL-2000 -- A toy camcorder that used compact audio cassette to store video.
- SteadyShot
- USB streaming
- Dew warning
[edit] External links
- Understanding Recordable & Rewritable DVD by Hugh Bennett
- How Camcorders Work from HowStuffWorks
- Canon museum includes dozens of video camera and camcorder details from 1981.
- Magnetic tape construction and archival problems.
