Category Archives: O


Ofcom describes itself as the ‘Independent regulator and competition authority for the UK communications industries’. Its responsibilities include telecommunications and radio and television broadcasting – ranging from licensing radio and TV channels to customer complaints.


Orthogonal Frequency Division Multiple Access is a technology used for terrestrial radio return channels. Generally it provides several users with simultaneous low data rate transmission for fixed and mobile applications. Power can be less than a Watt and will communicate over considerable distances. OFDMA is used in the IEEE 802.16-2005 Mobile WiMAX broadband wireless access standard, enabling mobile DSL services and mobile telephony to provide customers with enhanced voice and data services.


Offline (editing)

A decision-making process using low-cost equipment to produce an EDL or a rough cut which can then be conformed or referred to in a high quality online suite – so reducing decision-making time in the more expensive online environment. Most offline suites enable shot selection and the defining of basic transitions such as cuts and dissolves which are carried by EDLs. AAF provides an open standard for transporting a much wider range of decisions, including DVE, color corrections, as well as other metadata, between systems from different manufacturers.

With on-line video quality now available on low-cost computers there is a choice of skipping offline and editing broadcast quality footage very cost-effectively, or continuing to use off-line, depending on the requirements of the project and budgets.


Open IPTV Forum. This has become a part of the HbbTV Assoication, and so very much involved with accelerating the deployment of IPTV services.


See also: AAF


Organic Light Emitting Diode technology is used to make displays for video, computer screens, mobile devices, and more. Light is generated when a voltage is applied across an emissive electroluminescent layer of an organic (containing carbon) semiconductor compound via two electrode layers. The brightness of the light from each diode is varied according to the video input – unlike ‘LED’ screens that are predominant in the current screen market. Here the LEDs provide a white backlight behind an LCD (liquid crystal display) that works as a red, green and blue light filter for each pixel that is controlled by the input image (video, etc).

The OLED technology offers a number of benefits over LED screen technology. As there is no backlight, when the OLEDs are switched off there is no light emitted. Black really looks black, and the screens are specified with a very high contrast ratio. They also offer a faster response time, wider viewing angles and larger color gamuts. As a result the images look very good and they they are often used as monitors. As it is easy to put the OLEDs very close together it is possible to make very small screens that deliver full resolution images – useful for viewfinders, handheld devices, phone, etc. An OLED screen’s power consumption is less than equivalent LED screen as almost all the light generated is visible, none absorbed in filters. The screens can be very thin. An early 50-inch consumer model was boasting 6mm thickness. The screens can be bent, and some manufacturers are offering curved screens. Perhaps OLEDs may be used to make a roll-up screen.

On the downside, OLED screens are still offered at a substantial price premium over LED versions. Also it is said that the life expectancy of OLED screens is considerably less than that of LEDs, mainly due to the relatively short life of the blue OLEDs. Work continues to improve that area.

OLED screens have been produced for a number of years but only recently have been widely available in the consumer market.

See also: Quantum dot, SED


Open Media Framework Interchange is an open standard developed by Avid, for post production interchange of digital media among applications and across platforms. It describes a file format and supports video, audio, graphics, animation and effects as well as comprehensive edit decision information. Transfers may be by removable media or over a high-speed network.


One light (pass)

A one-light pass refers to a film-processing lab giving the same exposure to a defined length of film, during printing. This is the simplest, quickest and cheapest way to print all the film and the results are typically used for making rushes, dailies, etc. These are often subsequently telecined and recorded to videotape as a reference for the offline decision-making process.

See also: Best light

Online (editing)

Production of the complete, final edit performed at full program quality; the buck stops here! Being higher quality than offline editing, time costs more but the difference has narrowed as the cost of equipment has reduced. Preparation in an offline suite will help save time and money in the online. To produce the finished edit, online has to include a wide range of tools, offer flexibility to try ideas and accommodate late changes, and to work fast to maintain the creative flow and to handle pressured situations.

Open Systems Interconnect (OSI)

The Open Systems Interconnection (OSI) Basic Reference Model describes a general structure for communications, defined by the ISO, which comprises seven layers and forms a framework for the coordination of current and future standards, but not defining the standards themselves.



OpenEXR is a file format developed by Industrial Light & Magic for high dynamic range (HDR) images that are used in computer imaging applications. It is used by ILM on motion pictures, has become ILM’s main image file format, and is released as free software. It offers a higher dynamic range than 8 or 10-bit pictures, support for 16-bit floating-point, 32-bit floating-point, and 32-bit integer pixels, up to 2:1 lossless compression algorithms, and extensibility to add new compression codecs and image types. It forms the container for the ACES color format.

See also: ACES, Color Transform Language

Operating system (OS)

The base program that manages a computer and gives control of the functions designed for general purpose usage, not for specific applications. Common examples are MS-DOS, Windows and Linux for PCs, OSX for Apple Macintosh and UNIX. The operating system provides the connections to keyboards, networks, storage and displays. For actual use, such as word processing, there are specific applications software packages that run on top of the operating system. For high performance applications such as video editing the developer needs to minimise the use of the OS to ensure that the most compute cycles can be available for the application. Efficient use of the OS and its facilities are key to producing smooth and interactive interfaces between operator and machine.

See also: Threading

Optical disks

Disks that use optical techniques for recording and replay of material without the read/write heads touching the disk. These offer large storage capacities on ‘CD sized’ 5.25-inch (12 cm) polycarbonate disks with technologies including CD, DVD and Blu-ray Disc. These offer capacities of 700 MB for CD, 4.37- 15.90 GB for DVD and 25-128 GB for Blu-ray Disc. The CD format was designed for audio; DVD was designed for SD video and Blu-ray Disc for HD video. All have another life in data storage. They are all available in ROM and read/write forms. The next development is expected to be a disk able to store a 4K UHD movie, which will also be useful for storing large quantities of data.

See also: Blu-ray Disc, DVD, Professional Disc, XDCAM

Orthostereoscopic (Stereoscopic)

A one-to-one condition where what is being displayed is the same as the ‘real world’. For example IMAX 3D is often shot with parallel cameras spaced at the average human adult interocular distance (approx 63.5 mm) and with wide angle lenses that closely match an audience member’s view of the screen.


Over-The-Top (content) refers to video and audio that is delivered over the broadband internet without involving broadcasters of cable, satellite or terrestrial television systems. The provider may be aware of the content but is not responsible for it, or in control of it.

See also: IPTV

Over sampling

Sampling information at a higher resolution than is required for the output format. For example, an HD picture can be regarded as an over sampled version of SD. SD pictures created from down sized HD are generally clearer, cleaner (lower noise) and sharper than those made directly in SD. This is because the size reduction process tends to lower noise and the output pictures are derived from more information than is available in a direct SD scan. An increasing amount of SD material is originated this way. Similarly, 35 mm film provides an over sampled source for SD and HD.