FireWire cameras use the

IEEE 1394 IEEE 1394 is an interface standard for a serial bus for high-speed communications and isochronous real-time data transfer. It was developed in the late 1980s and early 1990s by Apple in cooperation with a number of companies, primarily Sony a ...

bus A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a motor vehicle that carries significantly more passengers than an average car or van, but fewer than the average rail transport. It is most commonly used ...

standard Standard may refer to: Symbols * Colours, standards and guidons, kinds of military signs * Standard (emblem), a type of a large symbol or emblem used for identification Norms, conventions or requirements * Standard (metrology), an object ...

for the

transmission Transmission or transmit may refer to: Science and technology * Power transmission ** Electric power transmission ** Transmission (mechanical device), technology that allows controlled application of power *** Automatic transmission *** Manual tra ...

audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum *Digital audio, representation of sound ...

video Video is an Electronics, electronic medium for the recording, copying, playback, broadcasting, and display of moving picture, moving image, visual Media (communication), media. Video was first developed for mechanical television systems, whi ...

and control data.

FireWire IEEE 1394 is an interface standard for a serial bus for high-speed communications and isochronous real-time data transfer. It was developed in the late 1980s and early 1990s by Apple in cooperation with a number of companies, primarily Sony a ...

Apple Computer Apple Inc. is an American multinational corporation and technology company headquartered in Cupertino, California, in Silicon Valley. It is best known for its consumer electronics, software, and services. Founded in 1976 as Apple Computer Co ...

trademark A trademark (also written trade mark or trade-mark) is a form of intellectual property that consists of a word, phrase, symbol, design, or a combination that identifies a Good (economics and accounting), product or Service (economics), service f ...

for the IEEE 1394 standard. FireWire

camera A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...

s are available in the form of photo cameras and

video camera A video camera is an optical instrument that captures videos, as opposed to a movie camera, which records images on film. Video cameras were initially developed for the television industry but have since become widely used for a variety of other ...

s, which provide

image An image or picture is a visual representation. An image can be Two-dimensional space, two-dimensional, such as a drawing, painting, or photograph, or Three-dimensional space, three-dimensional, such as a carving or sculpture. Images may be di ...

and

data Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...

. A special form of video cameras is used in the domains of industry,

medicine Medicine is the science and Praxis (process), practice of caring for patients, managing the Medical diagnosis, diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, ...

astronomy Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest includ ...

microscopy Microscopy is the technical field of using microscopes to view subjects too small to be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical mic ...

and

science Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...

. These special cameras do not provide audio data. Fwcam overview padding

Structure

The

basic Basic or BASIC may refer to: Science and technology * BASIC, a computer programming language * Basic (chemistry), having the properties of a base * Basic access authentication, in HTTP Entertainment * Basic (film), ''Basic'' (film), a 2003 film ...

structure of FireWire cameras is based on the following six modules:

Optics

FireWire

s are based on CCD or

CMOS Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss ", , ) is a type of MOSFET, metal–oxide–semiconductor field-effect transistor (MOSFET) semiconductor device fabrication, fabrication process that uses complementary an ...

chips. The light-sensitive area, as well as the

pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a Raster graphics, raster image, or the smallest addressable element in a dot matrix display device. In most digital display devices, p ...

s of these chips, are small. In the case of cameras with integrated

optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes t ...

, we can assume that the optics are adapted to these chips. However, in the domains of

professional A professional is a member of a profession or any person who work (human activity), works in a specified professional activity. The term also describes the standards of education and training that prepare members of the profession with the partic ...

, and semi-professional

photography Photography is the visual arts, art, application, and practice of creating images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is empl ...

, as well as in the domain of special cameras, interchangeable optics are often used. In these cases, a system specialist has to adapt the optics and the chip to the application (see

System integration System integration is defined in engineering as the process of bringing together the component sub-systems into one system (an aggregation of subsystems cooperating so that the system is able to deliver the overarching functionality) and ensuring ...

). Besides normal

lenses A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...

, such interchangeable lenses may be

microscope A microscope () is a laboratory equipment, laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic ...

endoscope An endoscope is an inspection instrument composed of image sensor, optical lens, light source and mechanical device, which is used to look deep into the body by way of openings such as the mouth or anus. A typical endoscope applies several modern ...

telescope A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...

s, etc. With the exception of the standard C-mount and CS-mount, the mounts of interchangeable optics are company-specific.

Signal capture

Since the function of a FireWire camera depends upon electrical signals, the module "signal capture" transforms the incident

light Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...

, as well as the incident

sound In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the br ...

into

electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...

s. In the case of light, this process is performed by a CCD or CMOS chip. The transformation of the sound is performed by a

microphone A microphone, colloquially called a mic (), or mike, is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and publi ...

Digitization

The first step of the image's

digitization Digitization is the process of converting information into a digital (i.e. computer-readable) format.Collins Dictionary. (n.d.). Definition of 'digitize'. Retrieved December 15, 2021, from https://www.collinsdictionary.com/dictionary/english/ ...

results from the structure of a CCD or CMOS chip. It dissects the image into pixels. If a pixel has collected many photons, it creates a high voltage. Should there only be a few photons, a low voltage is created. "Voltage" is an analog value. Therefore, during the digitization's second step, the voltage has to be transformed into a digital value by an A/D converter. Now the raw digital image is available. A microphone transforms the sound into a voltage. An A/D converter transforms these analog values into digital ones.

Signal enhancement

The creation of

color Color (or colour in English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is the visual perception based on the electromagnetic spectrum. Though co ...

is based on a color filter, which is located in front of the CCD or CMOS chip. It is

red Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–750 nanometres. It is a primary color in the RGB color model and a seconda ...

green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a com ...

blue Blue is one of the three primary colours in the RYB color model, RYB colour model (traditional colour theory), as well as in the RGB color model, RGB (additive) colour model. It lies between Violet (color), violet and cyan on the optical spe ...

and changes its color from pixel to pixel. Therefore, the filter is called a

color filter array In digital imaging, a color filter array (CFA), or color filter mosaic (CFM), is a mosaic of tiny color filters placed over the pixel sensors of an image sensor to capture color information. The term is also used in reference to Electronic paper ...

or, after its inventor,

Bayer filter A Bayer filter mosaic is a color filter array (CFA) for arranging RGB color model, RGB color filters on a square grid of photosensors. Its particular arrangement of color filters is used in most single-chip digital image sensors used in digit ...

. Using these raw

digital image A digital image is an image composed of picture elements, also known as pixels, each with '' finite'', '' discrete quantities'' of numeric representation for its intensity or gray level that is an output from its two-dimensional functions f ...

s, the module "signal enhancement" creates an image, which meets aesthetic

requirement In engineering, a requirement is a condition that must be satisfied for the output of a work effort to be acceptable. It is an explicit, objective, clear and often quantitative description of a condition to be satisfied by a material, design, pro ...

s. The same is true for the audio data. In the final step, the module compresses the image and audio data and outputs them - in the case of video cameras - as a DV data stream. In the case of

photo A photograph (also known as a photo, or more generically referred to as an ''image'' or ''picture'') is an image created by light falling on a photosensitive surface, usually photographic film or an electronic image sensor. The process and pra ...

cameras, single images may be output and, if applicable, voice comments as files. The application domains of industry, medicine, astronomy, microscopy and science often use special

monochrome A monochrome or monochromatic image, object or palette is composed of one color (or values of one color). Images using only shades of grey are called grayscale (typically digital) or black-and-white (typically analog). In physics, mon ...

cameras. They forgo any

signal A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology. In ...

enhancement and thus output the digital image

in its raw state. Some special models of color cameras are only capable of outputting raw digital image data. Such cameras are called ColorRAW or Bayer cameras. They are often used in industry, medicine, astronomy, microscopy, and science. In form of photo cameras, they are used by professional photographers. Semi-professional photo cameras often offer an optional RAW mode. The enhancement of the raw digital data takes place outside the camera on a computer and therefore the user is able to adapt it to a particular application.

Interface

The first three modules are part of any digital camera. The interface is the module that characterizes the FireWire camera. It is based on the IEEE 1283 standard, defined by the organization "Institute of Electrical and Electronics Engineers". This standard defines a

, which transmits: # time critical data, for example, a video and # data whose integrity is of critical importance (for example, parameters or files). It allows the simultaneous use of up to 74 different devices (

s, scanners, video recorders,

hard disk A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating hard disk drive platter, pla ...

DVD The DVD (common abbreviation for digital video disc or digital versatile disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any ki ...

drives, etc.). Other standards, called "

protocols Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technology ...

" define the behavior of these devices. FireWire cameras mostly use one of the following protocols: ; AV/C : AV/C stands for "Audio Video Control" and defines the behavior of DV devices, for example, video cameras and video recorders. It is a standard, defined by the 1348 Trade Association. The Audio/Video Working Group is in charge of it. ; DCAM : DCAM stands for "1394-based Digital Camera Specification" and defines the behavior of cameras that output uncompressed image data without audio. It is a standard, defined by the 1394 Trade Association. The IIDC (Instrumentation and Industrial Control Working Group) is in charge of it. ; IIDC : IIDC is often used synonymously with DCAM. ; SBP-2 : SBP-2 stands for "Serial Bus Protocol" and defines the behavior of mass storage devices, such as hard disks. It is an

ANSI The American National Standards Institute (ANSI ) is a private nonprofit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organiz ...

standard maintained by NCITS. Devices that use the same protocol are able to communicate with each other. A typical example is the connection of a video camera and a video recorder. Thus, in contrast to the USB bus, there is no need to use a controlling computer. If a computer is used, it has to be compatible with the protocols of the device with which it is to communicate (please cf. Exchanging data with computers).

Control

The controlling module coordinates the other ones. The user may specify its behavior by: # switches outside the camera, # the FireWire bus, using

application software Application software is any computer program that is intended for end-user use not operating, administering or programming the computer. An application (app, application program, software application) is any program that can be categorized as ...

or # a hybrid of the first two cases.

Photo cameras

Professional and semi-professional photo cameras, and especially digital camera backs, offer FireWire interfaces to transfer image data and to control the camera. The image data's transfer is based on the protocol SBP-2. In this mode, the camera behaves as an external hard disk and thus enables the simple exchange of image files with a computer (please cf. Exchanging data with computers). To increase the work efficiency in a photo studio, additionally photo cameras and digital backs are controllable via the FireWire bus. Usually the camera manufacturer does not publish the protocol used in this mode. Therefore, camera control requires a specialized piece of software provided by the camera manufacturer, which mostly is available for

Macintosh Mac is a brand of personal computers designed and marketed by Apple Inc., Apple since 1984. The name is short for Macintosh (its official name until 1999), a reference to the McIntosh (apple), McIntosh apple. The current product lineup inclu ...

and

Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...

computers.

Video cameras

Although compatibility to the FireWire bus is only found in high-end photo cameras, it has usually been present in home-user level video cameras. Video cameras are mostly based on the protocol

AV/C FireWire cameras use the IEEE 1394 bus (computing), bus Standards organization, standard for the Transmission (telecommunications), transmission of Sound, audio, video and control data. FireWire is Apple Computer's trademark for the IEEE 1394 stan ...

. It defines the flow of audio and video data, as well as the camera's control signals. The majority of video cameras only provides the output of audio and video data via the FireWire bus ("DVout"). Additionally, some video cameras are able to record audio and video data ("DVout/DVin"). Video cameras exchange their data with computers and/or video recorders.

Special cameras

In the domains of industry, medicine, astronomy, microscopy and science FireWire cameras are often used not for aesthetic, but rather for analytical purposes. They output uncompressed image data, without audio. These cameras are based on the protocol DCAM (IIDC) or on company specific protocols. Due to their field of application, their behavior is considerably different from photo cameras or video cameras: # Their case is small and built mainly from metal and do not follow aesthetic, but rather functional design constraints. # The vast majority of special cameras does not offer integrated optics, but a standardized lens mount called " C-mount" or "CS-mount". This standard is not only used by lenses, but also by microscopes, telescopes, endoscopes and other optical devices. # Recording aids, such as

autofocus An autofocus (AF) optical system uses a sensor, a control system and a motor to focus on an automatically or manually selected point or area. An electronic rangefinder has a display instead of the motor; the adjustment of the optical system h ...

or image stabilization are not available. # Special cameras often utilize monochrome CCD or CMOS chips. # Special cameras often do not apply an infrared cut filter or optical low pass filters, thus avoid affecting the image. # Special cameras output image data streams and single images, which are captured using an external trigger signal. In this way, these cameras can be integrated into industrial processes. #

Mass storage In computing, mass storage refers to the storage of large amounts of data in a persisting and machine-readable fashion. In general, the term ''mass'' in ''mass storage'' is used to mean ''large'' in relation to contemporaneous hard disk drive ...

devices are not available since the images have to be analyzed more or less immediately by the computer connected to the camera. # The vast majority of special cameras is controlled by application software, installed on a computer. Therefore, the cameras do not have external switches. # Application software is rarely available off-the-shelf. It usually has to be adapted to the specific application. Therefore, camera manufacturers offer programming tools designed for their cameras. If a camera uses the standard protocol DCAM (IIDC), it can also be used with third-party software. A lot of industrial computers and

embedded system An embedded system is a specialized computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is e ...

s are compatible to the DCAM (IIDC) protocol (please cf. Structure / Interface and Exchanging data with computers). In comparison to photo or video cameras, these special cameras are very complifcated. However, it makes no sense to use them in an isolated manner. They are, like other sensors, only components of a bigger system (please cf.

Exchanging data with computers

FireWire cameras are able to exchange data with any other FireWire device, as long as both devices use the same protocol (please cf. Structure / Interface). Depending upon the specific camera, these data are: * Image and audio files (protocol: SBP-2) * Image and audio data flows (protocol:

or DCAM (IIDC)) * Parameters to control the camera (protocol:

or DCAM (IIDC)) Fwcam open vs prop padding

If the camera is to communicate with a computer, this computer has to have a FireWire interface and to use the camera's protocol. The old days of FireWire cameras were dominated by company specific solutions. Some specialist offered interface boards and drivers, which were accessible only by their application software. Following this approach, application software is in charge of the protocol. Since this solution utilizes the computing resources in a very efficient manner, it is still used in the context of highly specialized, industrial projects. This strategy often leads to problems, using other FireWire devices, as for instance hard disks. Open systems avoid this disadvantage. Open systems are based on a layer model. The behavior of the single layers (interface board, low level driver, high level driver and

API An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...

) follows the constraints of the respective operating system manufacturer. Application software is allowed to access operating system APIs, but never should access any level lower. In the context of FireWire cameras, the high level drivers are responsible for the protocol. The low level drivers and the interface boards put the definitions of the standard IEEE 1394 into effect. The advantage of this strategy is the simple realization of application software, which is independent of hardware and specific manufacturers. Especially in the domains of photo cameras and special cameras hybrids between open and company specific systems are used. The interface boards and the low level drivers typically adhere to the standard, while the levels above are company specific. The basic characteristic of open systems is not to use the APIs of the hardware manufacturers, but those of the operating system. For Apple and Microsoft the subject "image and sound" is of high importance. According to their APIs -

QuickTime QuickTime (or QuickTime Player) is an extensible multimedia architecture created by Apple, which supports playing, streaming, encoding, and transcoding a variety of digital media formats. The term ''QuickTime'' also refers to the QuickTime Pla ...

and

DirectX Microsoft DirectX is a collection of application programming interfaces (APIs) for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms. Originally, the names of these APIs all began with "Direct" ...

- are very well known. However, in the public perception they are reduced to the reproduction of audio and video. Actually, they are powerful APIs that are also responsible for image acquisition. Under Linux this API is called video4linux. It is less powerful than QuickTime and DirectX and therefore additional APIs exist besides video4linux: Fwcam linux padding

; Photo cameras : Photo cameras usually use Linux' infrastructure for mass storage devices. One of the typical applications i
digiKam
; Video cameras : Video cameras are accessed by various APIs. The image to the right depicts the access of the video editing softwar
Kino
to th
libavc1394
API. Kino also accesses other APIs which are not shown in the image to simplify matters. ; Special cameras : The most important API for special cameras i
libdc1394
The image to the right depicts the access of the application softwar
Coriander
to this API. Coriander controls FireWire cameras that are based on the protocol DCAM (IIDC) and acquires their images. In order to simplify the use of video4linux and the dedicated APIs, the meta AP
unicap
has been developed. It covers their bits and pieces with the aid of a simple programming model.

System integration

Often FireWire cameras are only a cog in a bigger system. Typically, a system specialist uses a number of different components to solve a particular problem. There are two basic approaches to do this: # The problem at hand is interesting enough for a group of users. The typical indicator of this situation is the off-the-shelf availability of application software. Studio photography is an example. # The problem at hand is only of interest to a particular application. In such cases, there is typically no application software available off-the-shelf. Therefore, it has to be written by a system specialist. The gauging of a steel plate is an example. Many aspects of system integration are not directly related to FireWire cameras. For example, illumination has a very strong influence on the quality of the acquired images. This holds true for both aesthetic and analytical applications. However, in the context of the realization of application software, there is a special feature, which is typical for FireWire cameras. It is the availability of standardized protocols, such as

, DCAM, IIDC and SBP-2 (please cf. Structure / Interface and Exchanging data with computers). Using these protocols, the software is written independently from any particular camera and manufacturer. By leaving the realization of the protocol to the operating system, and by enabling access to a set of APIs, software can be developed independently from hardware. If, for instance, under Linux a piece of application software uses the API libdc1394 (please cf. Exchanging data with computers), it can access all FireWire cameras that use the protocol DCAM (IIDC). Using the API unicap additionally permits access to other video sources, such as frame grabbers.