Tag : Connectivity

8P8C

Connector for the ubiquitous dual unshielded twisted pair (UTP) Cat 5 or Cat 6 Ethernet cable – A.K.A. RJ45. These are those extremely common connectors that, for instance, are used on the ends of the cable that plug between an internet modem and a computer. As the use of IT products proliferates in some areas of television such as program playout and services for the internet, so the use of Ethernet and 8P8C connectors grows. It could be said that they are the IT version of the still-widely-used BNC.

See also: 13.5, Tri-level sync

 

Adaptive bit-rate streaming

The streaming of media often occupies a large part of a network’s available capacity, especially if the media is video and the network is the Internet – where video streaming is growing fast. The available data speed for users on the Internet varies all the time but video and audio are constant flows, with the video requiring substantial bandwidth to deliver good pictures. Relying on a constant bit rate may well run out of bandwidth, then the video freezes while waiting for the next frames – a process known as buffering.

A way around this is to vary the bit rate according to the available capacity of the network connection. This is adaptive bit-rate streaming. There are several versions in use. Generally these involve the sender system detecting the receiver’s available bit rate and CPU power, and then adjusting the sending bit rate accordingly by varying the amount of compression applied to the media. In practice this requires the sender’s coder simultaneously creating a set of streams, typically three, each with a different bit rate. These are made available as a series of files containing short sections of video, typically between 2 and 10 seconds. This way those with a fast connection see good quality video, and those with a slow one hopefully should still see satisfactory results. In practice, streaming starts with sending a manifest of the files, and then low bit-rate video files. Then, if the receiver sees there is room for a better quality level, it will ask for it. If bandwidth is getting too tight, it will switch down.

Quantel has developed this concept further in its QTube technology using virtualization to create variable bit rate data on the fly to suit the speed of the connection as it changes over time.

See also: Buffering, HTTP Live Streaming, HTTP Smooth Streaming, MPEG-DASH

ADSL

Asymmetrical Digital Subscriber Line, working on the copper ‘local loop’ originally installed to connect phones to the exchange for communication by voice, ADSL adds a broadband downstream channel (to the user) of maximum 8 Mb/s and a narrower band upstream channel (from the user) of maximum 128-1024 kb/s, according to class. As the upstream and downstream speeds are different the service is called ‘asymmetrical’ (a widely used technique to keep the customers’ equipment technically simpler, and lower cost, with larger, more complex equipment at the supplier, e.g., telephone and TV services, MPEG compression, etc). Exactly how fast an ADSL circuit can run ultimately depends on the performance of the line (including the customer’s own wiring), and is often dictated by the distance from the telephone exchange where the DSLAM terminates the line. The highest speeds are usually only available within 1.5 km of the DSLAM. The service is normally always-on, no need to dial up. Its uses include high-speed Internet connections and streaming video.

ADSL-2 can run up to 12 Mb/s over up to 2.5 km, and ADSL-2+ can deliver 24 Mb/s over up to 1.5 km. ADSL-2/2+ effectively doubles this rate by putting two services together (all distances are approximate). These are sufficient to carry live SD or HD provided that the service is continuous, or can be recorded before viewing.

See also: Broadband, DSL, DSLAM

API

Application Programming Interface; a set of interface definitions (functions, subroutines, data structures or class descriptions) which provide a convenient interface to the functions of a subsystem. They also simplify interfacing work by insulating application programmers from minutiae of the implementation.

Arbitrated Loop (AL)

A technique used on computer networks to ensure that the network is clear before a fresh message is sent. When it is not carrying data frames, the loop carries ‘keep-alive’ frames. Any node that wants to transmit places its own ID into a ‘keep-alive’ frame. When it receives that frame back it knows that the loop is clear and that it can send its message.

See also: Fibre Channel

Asynchronous (data transfer)

Carrying no separate timing information. There is no guarantee of time taken but a transfer uses only small resources as these are shared with many others. A transfer is ‘stop-go’ – depending on handshakes to check data is being received before sending more. Ethernet is asynchronous. Being indeterminate, asynchronous transfers of video files are used between storage devices, such as disks, but are not ideal for ‘live’ operations.

See also: Ethernet, Isochronous, Synchronous

ATM

1) Automatic Teller Machine (aka hole in the wall): a place to get cash.

2) Asynchronous Transfer Mode provides connections for the reliable transfer of streaming data, such as television. With speeds ranging up to 10Gb/s it is mostly used by telcos. 155 and 622Mb/s are most appropriate for television operations. Unlike Ethernet and Fibre Channel, ATM is connection-based: offering good Quality of Service (QoS) by establishing a path through the system before data is sent.

Sophisticated lower ATM Adaptation Layers (AAL) offer connections for higher layers of the protocol to run on. AAL1 supports constant bit rate, time-dependent traffic such as voice and video. AAL3/4 supports variable bit rate, delay-tolerant data traffic requiring some sequencing and/or error detection. AAL5 supports variable bit rate, delay-tolerant connection-oriented data traffic

Website: www.broadband-forum.org

AVB

Audio Video Bridging is, as of 2012, the Time-Sensitive Networking Task Group which aims to provide specifications to allow time-synchronized, low latency streaming services through IEEE 802 networks.

See also: Ethernet

Bandwidth

The amount of information (data) that can be passed in a given time. In television a large bandwidth is needed to show sharp picture detail in realtime, and so is a factor in the quality of recorded and transmitted images. For example, ITU-R BT.601 and SMPTE RP 125 allow analog luminance bandwidth of 5.5 MHz and chrominance bandwidth of 2.75 MHz for standard definition video. 1080-line HD has a luminance bandwidth of 30 MHz (ITU-R BT.709).

Digital image systems generally require large bandwidths hence the reason why many storage and transmission systems resort to compression techniques to accommodate the signal.

BGAN

Broadband Global Area Network comprises three Inmarsat satellites. The service they provide is free of terrestrial troubles such as cellular dead-zones, or disaster service outages, and is available around the world – even on oceans and in deserts. Just make sure there are no obstacles between you and the satellite. Using a small, easy-to-set-up dish, it can offer phone, fax, ISDN, SMS text, and high-speed internet services.

Bluetooth

Short-range, up to 100m, wireless data connection in a Personal Area Network (PAN). Bluetooth is used in products such as phones, printers, modems and headsets and is acceptable where two or more devices are in proximity to each other and not needing high bandwidth (3 Mb/s max.). It is easy to set up without configuration as Bluetooth devices advertise all services they provide making using the service easily accessible, without network addresses, permissions and all the other considerations that go with typical networks.

Website: www.bluetooth.com

Broadband

General term referring to internet connections that are faster than those using a dial-up telephone modem. i.e. receiving (download) much faster than 56 kb/s and transmitting (upload) faster than 28 kb/s. Broadband connects subscribers to the internet via DSL or ADSL over the original copper telephone lines. Cable services can offer higher data rates, especially those using fiber-optic cable to the home (FTTH). Generally broadband speeds are capable of carrying real-time video to homes, except in the evenings, when everyone else is trying to do the same!

See also: ADSL

Buffering

Informal word used to describe when streaming media suddenly ‘hits the buffers’ – stops. This is usually due to a lack of bandwidth when viewing video over the internet. In recent years the implementation of adaptive streaming schemes, as well as faster internet, have together greatly reduced the occurrence of buffering, making the viewing of video delivered via the internet a non-buffered experience.

BXF

Broadcast eXchange Format standardizes interfaces among systems that deal with content metadata, content movement, schedules and as-run information. This is standardized in SMPTE RP 2021 and simplifies interoperability between applications. BXF provides a standard where there were a large number of diverse ‘pet’ or old file and data formats used in areas including schedules, playlists, record lists, as-run lists, content metadata, content movement instructions.

BXF makes it possible for all its users to have a common standard for the efficient exchange of data between all components of broadcast automation and business systems.

CIFS

Common Internet File System is a platform-independent file-sharing system that supports rich, collaborative applications over the internet which could be useful for collaborative post production workflows. It defines a standard remote file-system access protocol, enabling groups of users to work together and share documents via the Internet or within intranets. CIFS is an open, cross-platform technology based on native file-sharing protocols in Windows and other popular PC operating systems, and is supported on other platforms, so users can open and share remote files on the Internet without installing new software or changing work methods.

CIFS allows multiple clients to access and update the same file, while preventing conflicts by using sophisticated file-sharing and locking semantics. These mechanisms also permit aggressive caching and read-ahead/write-behind without loss of cache coherency.

CIFS also supports fault tolerance in the face of network and server failures.

In Quantel’s Genetic Engineering teamworking infrastructure, the Sam data server virtualizes media on-the-fly to give third-party applications instant access to all stored media using the CIFS protocol for no-API, out-of-the-box connectivity.

Website: www.microsoft.com/mind/1196/cifs.asp

Cloud

For years computer network engineers have occasionally drawn a cloud in their diagrams – implying a distant reach of the network; usually somewhere where more storage can be accessed. Today, with reasonably high speed internet widely available, that fluffy thing has achieved front-of-stage importance with a rapid expansion of cloud computing service providers offering both storage and processing in their cloud. Or you can even have your own private cloud if you want.

Note that this is not a data center, requiring your computer to have the processing power and programs (apps) to alter and edit your video or audio. Cloud computing can be highly asymmetric – your computer only has to run a browser and upload video to the cloud, in theory all the rest could be done in the cloud – depending on the tools available and how you want to work.

Typically these clouds are accessed via the Internet and offer access to any amount of your uploaded data from any internet connection. There is a very wide range of services available, such as payrolls, tax returns, sales coordination, etc. Some providers offer specific services for the media industry, specializing in video storage, viewing and editing via their cloud. Uploading newly shot footage and editing can be done from anywhere with an internet connection. Once in the cloud, all those allowed to can access the footage by logging onto the website. This has major benefits for location shoots; not least being able to deliver valuable new footage to a safe place without moving. It also helps with studio productions as all required personnel can contribute to the production and post-production, without having to move from their laptop.

Technically cloud services divide into three recognized types:

Software as a Service (SaaS) is popular as it only requires a modest computer on the ground, which basically just has to support a web browser, because all the software and probably quite a bit of storage needed is in the cloud. So, for example, freshly shot video footage could be stored in the cloud. Then it could be, viewed, edited, and reviewed. Another powerful use is planning and organizing production, so everyone is kept up to date.

With Platform as a Service (PaaS) users can run their own applications, provided that it fits with what cloud service operators offer in terms of platforms. When using Infrastructure as a Service (IaaS) you can run whatever programs you like on the cloud’s available hardware

CMTS

Cable Modem Termination System is located at a cable headend / hub and connects to the customers’ lines and can provide fast data services, including Internet, to its customers.

Common Image Format (CIF)

The ITU has defined common image formats. A standard definition image of 352 x 240 pixels is described for computers. For HDTV production the HD-CIF preferred format is defined in ITU-R BT.709-4 as 1920 x 1080 pixels, 16:9 aspect ratio with progressive frame rates of 24, 25 and 30 Hz (including segmented scan) and interlace field rates of 50 and 60 Hz. This has helped to secure the 1920 x 1080 format as the basis for international program exchange.

See also: ITU-R BT.709

Compression (video)

The process of reducing the bandwidth or data rate required to transport a video or audio stream. The old analog broadcast standards, PAL, NTSC and SECAM are, in fact, compression systems which greatly reduce the information that was present in the original RGB sources.

Digital compression systems analyze their sources, such as pictures and sound, to find and remove redundancy both within the signal. Some of the techniques were primarily developed for digital data transmission but have been adopted as a means of reducing broadcast transmission bandwidths and storage requirements on disks and VTRs.

A number of compression systems are in regular use for moving images. These include ETSI, JPEG, Motion JPEG, JPEG 2000, DV, MPEG-1, MPEG-2, MPEG-4, AVC, H.264, Windows Media, Real and many more. Where different techniques are used in the same workflow, quality problems can occur and picture quality/ audio can suffer more than if the same method is used throughout.

The MPEG-2 family of compression schemes, which was originally designed for program transmission, has been adapted for studio use in Betacam SX and IMX recorders.
While there is much debate, and new technologies continue to be developed, it remains true that the best compressed results are produced from the highest quality source pictures. Poor quality inputs do not compress well. Noise, which may be interpreted as important picture detail, is the enemy of compression.

The need for ever more efficient compression systems is partly driven by the bigger TV picture formats, HD images are about five times the area of SD. More recently UHDTV-1 (4K) and UHDTV-2 (8K), respectively are 4 and 16 times the picture area of 1920 x 1080 HD. New HEVC / H.265 coding is expected to be twice as efficient as MPEG-4, which is already twice as efficient as MPEG-2. This efficiency combined with the twice-as-efficient DVB-T2 and DVB-S2, together mean that 32 SD channels can now broadcast in the space that used to carry one anaolg TV channel. It also means that the channel could carry one 4K TV channel.

See also: Compression ratio, Concatenation, Digital Betacam, ETSI, HEVC, JPEG, JPEG 2000, MPEG-2, MPEG-4, Windows Media

Connected TV

A television service that typically allows viewing recent programs and the internet in general. Early versions of this made use of a set-top box with an internet connection, today it can be accessed with an all-in-one smart TV.

See also: Smart TV

DC-SDI

An HD SDI dual link arrangement that is configured to carry live uncompressed DCI-sized 2K footage. That is 2048×1080 pixel images at 24P, with 12-bit 4:4:4 sampling in X´Y´Z´ color space. This involves a constant data rate of at least 1913 Mb/s, too much for a single HD-SDI, designed for 1080/60I/30P 10-bit 4:2:2 bit rate of 1248 Mb/s and audio. Hence the use of a dual link.

See also: Dual link

DFS

Distributed File System. Used to build a hierarchical view of multiple file servers and shared files on a network. Instead of having to think of a specific machine name for each set of files, users only need to remember one name as the key to a list of shared files on multiple servers. DFS can route a client to the closest available file server and can also be installed on a cluster for even better performance and reliability. Medium-to-large sized organizations are most likely to benefit from using DFS while smaller ones should be fine with ordinary file servers.

DisplayPort

A digital display interface developed by the Video Electronics Standards Association (VESA). At first glance the connectors look like HDMI, but it is designed to cover a wide range of image standards, carries packetized data and typically connects a computer to a screen. It can also carry audio and other data. In 2006 version 1 offered up to 8.64 Gb/s data over a 2-meter cable. Capabilities have grown and now V 1.3 offers an overall bandwidth of 32.4 Gb/s – enough to carry up to 5K (5120 x 2880) RGB, and 8K UHD at 60 Hz with 4:2:0 sampling. It also has an HDMI 2.0 compatibility mode.

Website: www.displayport.org

DOCSIS

Data Over Cable Service Interface Specification enables the addition of high-bandwidth data transfers to existing cable-TV (CATV) systems. Developed by CableLabs and others, it was first released in 1997, and is now widely used by cable television operators to provide Internet access over their existing hybrid fiber-coaxial (HFC) infrastructure. The communication is via the free spectrum that is otherwise used for TV channels: 6 MHz in North America and 8 MHz in Europe – where EuroDOCSIS, a variation of DOCSIS, offers greater data rates. DOCSIS 3.0, introduced in 2011, has provided services up to 100 Mb/s, and beyond. That same year UK broadband provider Virgin Media announced trials with a download bandwidth of 1.5 Gb/s and upload 150 Mb/s. DOCSIS 3.1 (2013) introduced an OFDM modulation system (as used in DVB TV) using smaller 20 kHz to 50 kHz-wide subcarriers which can be aggregated into a block of up to 200 MHz.

Website: www.docsis.org, www.cablelabs.com

DSL

Digital Subscriber Line. A general term for a number of techniques for delivering data over the telephone local loop (between exchange and user) – the copper wires that make up the so called ‘last mile’. Referred to generically as xDSL these offer much greater data speeds than modems on analog lines – up to 32 Mb/s upstream to the computer and 1 Mb/s or more downstream.

See also: ADSL

DSLAM

Digital Subscriber Line Access Multiplexer, usually located at the local telephone exchange, it connects multiple customer DSL lines to a high-speed ATM internet backbone line. It is the device that communicates with our ADSL (and SDSL) modems, creating a network similar to a LAN but without Ethernet distance restrictions, to provide an Internet connection for subscribers.

Dual link

The bandwidth of SDI and HD-SDI links allow the transport of uncompressed 4:2:2 sampled video and embedded digital audio. Dual links are often used to carry larger requirements, such as video with key (4:2:2:4), RGB (4:4:4) and RGB with key (4:4:4:4). Dual link for SD is defined in ITU-R/BT.799-2 and RP 175-1997. Dual link at HD is used for stereo3D and 50/60 P.

A dual link is arranged to allow some meaningful monitoring of each of the two links with standard equipment. So RGB is sent with Link A carrying full bandwidth G, half R and B (4:2:2). Link B is just half bandwidth R and B (0:2:2). RGB + Key is sent as (4:2:2) and (4:2:2).

See also: 0:2:2, 4:2:2, HD-SDISDI, Y Cr Cb

Website: www.itu.ch

Duplex

(Full duplex) refers to communications that are simultaneously two-way (send and receive) like the telephone. Those referred to as half-duplex switch between send and receive.

Ethernet

Ethernet is a form of Local Area Network (LAN) widely used for interconnecting computers and standardized in IEEE 802.3, allowing a wide variety of manufacturers to produce compatible interfaces and extend capabilities – repeaters, bridges, etc. The data transmission rate is 10, 100 Mb/s up to 1 and 10 Gb/s, but overheads in packaging data and packet separation mean actual throughput is less than the ‘wire speed’ bit rate.

There are many connection methods for Ethernet varying from copper to fiber optic. Currently the three most common are:

10 Base-T The standard for 4-wire twisted pair cable using RJ connectors. This gives extremely low cost-per-node network capabilities.

100 Base-T (a.k.a. Fast Ethernet) 100 Mb/s 4-wire twisted pair cable using RJ connectors is now becoming very popular. Similar technology to 10 Base-T but uses Cat. 5 cable.

Gigabit Ethernet (GigE) Development of existing Ethernet technology to support 1,000 Mb/s. This is specified for both fiber and copper Cat. 5e.

10 Gigabit Ethernet (10GigE) only functions over copper for short distances – 15 meters using twinax cable. Using augmented cat. 6 (Cat 6A) cable it may travel twice that distance. For longer range optical fiber is the only answer. This only operates in full-duplex mode – so collision detection protocols are unnecessary. But the packet format and other current Ethernet capabilities are easily transferable to 10GigE.

100 Gigabit Ethernet (100GigE) continues the x10 steps of Ethernet data speed evolution. Destined to travel over optical fiber, it is at the development stage but will doubtless emerge into the commercial world sometime soon.

See also: Hub, CSMA/CD
Switch Websites: www.ethernetalliance.org
www.ethermanage.com/ethernet/ethernet.html

Fibre Channel (FC)

An integrated set of standards developed by ANSI designed to improve data speeds between workstations, supercomputers, storage devices and displays while providing a single standard for networking storage and data transfer. It can be used point-to-point, switched or in an arbitrated loop (FC-AL) connecting up to 126 devices.

Planned in 1997 to run on a fiber-optic or twisted-pair cable at an initial data rate of 1Gb/s, it has been consistently upgraded to make, 2, 4, 8 and 14 Gb/s (14GFC) available. Expect both 28 and 4 x 28 Gb/s in 2015. There is a road map sketched to 2028 with the possibility of about an 8-fold further increase in speed. These are nominal wire speeds but 8b/10b encoding is used to improve transmission characteristics, provide more accuracy and better error handling. With every 8-bit data byte for transmission converted into a 10-bit Transmission Character, the useful data rate is reduced by 20 percent.

Because of its close association with disk drives, its TV application is mostly, but not always, in the creation of storage networking. It can interface with the SCSI disk interface, which is key to its operation in storage networking such as SAN.

See also: SAN

Website: www.fibrechannel.org

File transfer

A discontinuous transfer process which treats each transferred item as a single block, neither divisible into smaller, independent elements nor part of a larger whole. As the transfer process has a recognizable beginning and end (unlike streaming) it is possible for the complete transfer to be checked and any errors corrected. This is not possible with a streaming process.

File transfer requires material to be complete and clearly identifiable. When handling time-based material, such as video and audio, the complete file has to be available before transfer can start. If the whole clip is a single file, this cannot be transferred until all the material is complete. However, if the clip is sub-divided, for example into frames, the transfer can start immediately after the first frame is completed. This becomes important in time sensitive applications such the live editing of highlights while the event is still taking place.

See also: Streaming

FTP

File Transfer Protocol. The high level Internet standard protocol for transferring files from one machine to another. FTP is usually implemented at the application level.

See also: FXP

FTTX

A generic acronym for Fiber To The X – a broadband network that uses optical fiber to provide all or part of the local loop used for the ‘last mile’ connection to the customer. X can be H – home, N – neighborhood, D – desktop, N – to the street cabinet or node, C – cabinet, P – premises, etc. Fiber can typically operate over quite long distances – typically 10 km or more, capable of delivering digital services, often broadband internet, at speeds of 1 Gb/s or more. However, the internet provider may well not be delivering the service at such a high speed.

See also: G.fast

FXP

File eXchange Protocol uses FTP to transfer data directly from one remote server to another. This inter-server exchange operates without the data being routed to the client. Whereas normal FTP involves data transfers only between a client and a server, using FXP involves the client using an FTP connection to the two servers to command the data transfer. This can be particularly useful when moving large files, such as video, as it is only the connection between the two servers that needs to be fast; the client’s command operation requires only low bandwidth.

G.fast

A high-speed digital subscriber line (DSL) standard for short local loops (the connection between the customer’s premises and the telecom’s network) that is expected to deliver from 150 Mb/s up to 1 Gb/s data rates over copper, and is slated as matching fiber at distances up to 400 metres. This means that many consumers can receive fast internet without running fiber to the house. The protocol is defined in Recommendation ITU-T G.9701. Such data rates are ample to support live 4K and even 8K UHD streaming to viewers’ homes. The first consumer installations of this technology are expected in late 2015.

Gateway

A device connecting two computer networks. For example, a gateway can connect a local area network (LAN) to a storage area network (SAN). This way a PC connected on an Ethernet LAN may have access to files stored on the SAN even though the PC is not SAN aware.

GSN

Gigabyte System Network was developed in 1999 for the efficient movement of large quantities of data. Applied to video, it allows realtime transfers of larger-than-HD images on a network. GSN allows transfer speeds up to 800MB/s, has low latency, and is an ANSI standard compatible with HIPPI, Ethernet, and other standard networks, providing full-duplex data transmission over up to 200m. It was not widely used as there were competing standards. Today its speed is overtaken by the later versions of Fibre Channel and SCSI, which are part of the mass computer market, so low priced.

HDMI

The High-Definition Multimedia Interface is a digital audio and video interface able to transmit uncompressed streams. It is used in both consumer and professional devices from television sets, to set-top boxes, camcorders, to games consoles, Blu-ray Disc players… and more. It replaces a big pile of lumpy analog connections such as SCART, composite video, as well as DVI, audio and more. In 2013, 10 years after the specification was released, over 3 billion HDMI devices had been sold.

Connectors:
Type A standard 19-pin – very widely used.
Type B 29-pin not used yet but ready for large video formats such as WQUXGA (3,840×2,400).
Type C is a mini version of Type A, intended for mobile devices.
Type D is a micro version, even smaller than Type C.
Type E is the Automotive version with a locking tab and a shell to keep water out.

The Version 1.1 specification supports a maximum pixel clock rate of 165 MHz, sufficient for1080/60P and WUXGA (1920×1200) and 8-channel 192 kHz 24-bit audio as well as compressed streams such as Dolby Digital. The current HDMI 1.3 offers 340 MHz capability – beyond WQSXGA (3200 x 2048) – and offers future proofing.

The data carried on HDMI is encrypted using High-bandwidth Digital Content Protection (HDCP) digital rights management technology – meaning that the receiving end needs to be able to decrypt HDCP.

HIPPI

High performance parallel interface (ANSI X3.283-1996). Capable of transfers up to 200 MB/s (800 with the 6400 Mb/s HIPPI, a.k.a. GSN) it was targeted at high performance computing and optimized for applications involving streaming large volumes of data rather than bursty network activity. The parallel connection is limited to short distance and so Serial HIPPI is now available.This is now a largely obsolete technology being replaced by optical fiber and high performance network architectures.

See also: GSN

HSDPA, HSUPA and HSPA

High-Speed Downlink Packet Access is an enhanced 3G mobile telephone communications protocol. Also dubbed 3.5G, 3G+, and Turbo 3G, HSDPA allows networks based on the Universal Mobile Telecommunications System (UMTS) to offer enhanced down-link data rates up to 99.3 Mb/s. The more recent HSPA+ (High-Speed Packet Access) can achieve speeds of 337.5 Mb/s. The high-speed down-link data channel from the base station is shared between its mobile users, and constantly re-scheduled according to the quality of the radio link to each phone. The data speeds made available the delivery of good quality live video to mobile phones.

HTTP

HyperText Transfer Protocol provides the basis for data communication in the World Wide Web. It defines how messages are formatted and transmitted, and how web servers and browsers respond to commands. So a web address (URL) entered in a browser sends an HTTP command to a web server that then requests fetching and sending the page found at that URL.

See also: DASH

HTTP Live Streaming (HLS)

This HTTP-based media streaming protocol enables live streaming of audio or video over the internet for appropriate Apple products. It is a part of iOS, OS X, QuickTime and Safari and works by dividing the required source media into small chunks of around two seconds, then offering media files in several levels of H.264 video and MP3 or HE-AAC audio compression, providing from low to high bit-rate (and quality) delivered in an MPEG-2 Transport Stream. The data delivery system is adaptive to allow for variations of available data speeds, with the receiving end able to choose the highest bit-rate files it can receive fast enough to maintain live operation.

See also: Buffering, Adaptive bit-rate streaming

IEEE 1394a/b (a.k.a. FireWire, I-Link)

Developed by Apple and produced since 1994, it is a standard for a peer-to-peer serial digital interface which can operate at 400 to 3200 Mb/s (1394b) typically over shielded twisted pair cable up to 4.5m, and 100m on optical fiber.

Practically it can send A/V media over 100m of Cat-5 cable at 100 Mb/s. Consumers connect DV devices over longer distances using readily available low cost cables. IEEE 1394c has a data rate to 800 Mb/s over Cat5 cable and combines 1394 and GigE on one cable.

The high speed and low cost of IEEE 1394a makes it popular in multimedia and digital video applications. Uses include peer-to-peer connections for digital dub editing between camcorders, as well as interfacing video recorders, printers, PCs, TVs and digital cameras.

IEEE 1394 is recognized by SMPTE and EBU as a networking technology for transport of packetized video and audio. Its isochronous data channel can provide guaranteed bandwidth for frame-accurate realtime (and faster) transfers of video and audio while its asynchronous mode can carry metadata and support I/P. Both modes may be run simultaneously.

IEEE 1394 is known as FireWire by Apple, I-Link by Sony and Lynx by Texas Instruments. Future developments of FireWire are expected to increase data speed to 6.4 Gb/s.

See also: Asynchronous, Isochronous

Website: www.1394ta.org

IEEE 1588

This describes a Precision Time Protocol (PTP) that enables synchronizing distributed clocks to within 1 microsecond via Ethernet networks with relatively low demands on local clocks, the network and computing capacity. There are many applications for example in automation to synchronize elements of a production line (without timing belts).

PTP runs on IP networks, transferring precision time to slave devices via a 1 GHz virtual clock (timebase). Independent masters can be locked to one master clock, creating wide, or even global locking. SMPTE has been assessing the possibilities of using PTP as a synchronizing source for television applications.

 

See also: Black and burst, Tri-level sync

InfiniBand

InfiniBand defines an input/output architecture that can connect servers, communications infrastructure equipment, storage and embedded systems. It can achieve very high data transfers up to 120GB/s over copper and optical fiber connections, with the benefits of low latency and only requiring a low processing overhead. It is used in many data centers, high-performance computer clusters, connecting supercomputers, and in embedded applications that scale from two nodes up to a single cluster that interconnects thousands of nodes.

Interoperability

The ability of systems to interoperate; to understand and work with information passed from one to another. Applied to digital media this means video, audio and metadata from one system can be used directly by another. Digital signals may be originated in various formats and subjected to different types of compression so care is needed to maintain interoperability.

IP Datacast Forum (IPDC)

The IPDC (Internet Protocol Data Cast) Forum was launched in 2002 to promote and explore the capabilities of IP-based services over digital broadcast platforms (DVB and DAB). Participating companies include service providers, technology providers, terminal manufacturers and network operators. The Forum aims to address business, interoperability and regulatory issues and encourage pilot projects.

See also: IP over DVB

Website: www.ipdcforum.org

IP over DVB

The delivery of IP data and services over DVB broadcast networks. Also referred to as datacasting, this takes advantage of the very wideband data delivery systems designed for the broadcast of digital television, to deliver IP-based data services – such as file transfers, multimedia, Internet and carousels, which may complement, or be instead of, TV.

Due to DVB-T’s ability to provide reliable reception to mobile as well as fixed receivers, a new standard DVB-H has been added to send IP-style service to people on the move – typically to phones. For interactivity, a return path can be established by the phone.

See also: IP Datacast Forum, Data carousel

Isochronous

A form of data transfer that carries timing information with the data. Data is specified to arrive over a time window, but not at any specific rate within that time. ATM, IEEE 1394 and Fibre Channel can provide isochronous operation where links can be booked to provide specified transfer performance. For example, 60 TV fields can be specified for every second but their arrival may not be evenly spread through the period. As this is a guaranteed transfer it can be used for ‘live’ video but is relatively expensive on resources.

See: ATM, Asynchronous, Fibre Channel, IEEE 1394, Synchronous

MADI

Multichannel Audio Digital Interface, widely used among audio professionals, defines the data format and electrical characteristics of an interface carrying multiple digital audio channels, as in the Audio Engineering Society’s AES10-2008. It is popular for its large channel capacity: 28, 56, or 64 channels at up to 96 kHz, 24 bits per channel, and up to 3000m connections over optical fiber (or 100m over coax).

MHP

Multimedia Home Platform – DVB-MHP is open middleware from the DVB project for interactive television. It enables the reception and execution of interactive, Java-based applications on a TV set that can be delivered over a broadcast channel, together with the audio and video streams. The applications can provide information services such as games, interactive voting, e-mail, SMS and shopping. Some may require using an IP return channel.

Early deployments included DVB-T in Italy, DVB-S in Korea and Poland and DVB-C in Belgium. There have also been trails in other countries.

MOS

Media Object Server (protocol) – a communications protocol for newsroom computer systems (NCS) and broadcast production equipment. It is a collaborative effort between many companies to enable journalists to see, use, and control a variety of devices from their desktop computers, effectively allowing access to all work from one screen. Such devices include video and audio servers and editors, still stores, character generators and special effects machines.

MOS uses a TCP/IP-based protocol and is designed to allow integration of production equipment from multiple vendors with newsroom computers via LANs, WANs and the Internet. It uses a ‘one-to-many’ connection strategy – multiple MOSs can be connected to a single NCS, or a single MOS to many NCSs.

Website: www.mosprotocol.com

NFS

Network File System. Developed by Sun Microsystems NFS allows sets of computers to access each other’s files as if they were locally stored. NFS has been implemented on many platforms and is considered an industry standard.

See also: IP

OFDMA

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.

Website: www.runcom.com

OMFI

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.

Website: www.avid.com

PCI Express

This data interface is widely available on PCs. Unlike its predecessor PCI interfaces, PCIe provides fast serial connections which are more reliable for handling fast data than the parallel connections used with previous PCIs. A range of cards offer 1, 4, 8 or 16 full duplex (same speed both ways) data ‘lanes’. These are written as 1x, 4x, etc. A larger 32-lane card is available but rarely used. The cards are hot swappable.

PCIe is commonly used to connect storage such as optical and hard discs and SSD drives. The available data speed has increased over three versions so v3.0 offers a data speed up to 985 MB/s per lane.

See also: www.hardwaresecrets.com

RS 422

Not to be confused with 4:2:2 sampling or 422P MPEG, this is a standard for serial data communications defined by EIA standard RS-422. It uses current-loop, balanced signaling with a twisted pair of conductors per channel, two pairs for bi-directional operation. It is more costly than RS232 but has a high level of immunity to interference and can operate over reasonably long distances: up to 300m/1000 ft. RS 422 is widely used for control links around production and post areas for a wide range of equipment including, mixers, lighting, etc.

SAN

Storage Area Network is a well-established method of providing shared video storage and can offer platform-independent storage that may be accessed from, say, Windows, Linux and Mac OS workstations. It allows applications direct access to shared storage by cutting out the usual client-server ‘middle men’ to provide improved workflow and better work sharing on a common store.

SAN

The design recognizes that moving large amounts of data (video) is inconsistent with normal-network general-data traffic. Therefore it forms a separate network to connect data-hungry workstations to a large, fast array of disks. Although any network technology could be used, Fibre Channel predominates with current speeds of up to 14 Gb/s. SANs are scalable but additions may be complex to implement. Currently, expansion is ultimately limited by architecture and management considerations. However, in practice it can be difficult to sustain multiple high bandwidth (e.g. for HD or 4K) streams from a SAN. Quantel’s Genetic Engineering is designed to solve this problem and is capable of playing back multiple 2K and 4K streams simultaneously.

See also: FAN, Fibre Channel, NAS

Website: www.snia.org

SATA

Serial ATA (Advanced Technology Attachment) is designed to transfer data between disks drives (hard and optical) and computer hardware and is the successor of ATA. SATA adapters and devices communicate over a high-speed serial link originally specified in SATA I at 1.5 Gb/s, then SATA 2 at 3 Gb/s, SATA 3 at 6 Gb/s, and the latest SATA 3.2 offers a transport speed of 16 Gb/s.

The serial interface means the connector is smaller (than ATA) and can run faster, because fast parallel data starts to suffer from skewing with some channels of the parallel connection being faster/slower than others. Serial data cannot skew. SATA does not just serialize ATA. For example, SATA 2 added native command queueing, originally a feature of SCSI, that allows handling multiple pending transactions rather than just one at a time. Also disk drives can organize the transactions and so offer faster operation.

Website: www.sata-io.org

SCSI

The Small Computer Systems Interface started as a high data-rate, general-purpose parallel interface introduced in 1979 allowing up to eight devices to be connected to one bus (now 16 for Wide SCSI). This could comprise a controller and up to seven disks or devices of different sorts – hard disks, optical disks, tape drives, scanners, etc., and may be shared between several computers.

Since then SCSI has hugely increased in performance but is now used mainly on high-performance workstations and RAIDs on servers while other lower cost interfaces such as USB2 and IEEE1394 connect external devices, while SATA is used for many hard disks.

The original SCSI specified a cabling standard (50-way) that had to be kept short, a protocol for sending and receiving commands and their format. It is intended as a device-independent interface so the host computer needs no details about the peripherals it controls. SCSI’s continued development has resulted in ever faster data transfer rates. Currently 16GFC (Fibre Channel) has a maximum transfer rate of 1600 MB/s (12.6 Gb/s).

There are many other SCSI interfaces besides Fibre Channel. iSCSI (Internet Small Computer System Interface) can run over any physical transport capable of transporting Internet Protocol (IP). This gets much support as developments in Ethernet outpace those in FC. The performance of this though is network-dependent.

Serial SCSI using SSA (Serial Storage Architecture) FC-AL, IEEE1394, and Serial Attached SCSI (SAS), break away from the parallel cabling to offer data transfers currently up to 1200 MB/s. This is popular with many hard disk drives.

See also: Disk drives

SDTI

Serial Digital Transport Interface (SMPTE 305M). Based on the 270 Mb/s standard definition SDI, this provides realtime streaming transfers. It does not define the format of the signals carried but brings the possibility to create a number of packetized data formats for broadcast use. There are direct mappings for SDTI to carry Sony SX, HDCAM, DV-DIFF (DVCAM, DVCPRO 25/50, Digital-S) and MPEG TS. There is also an HD version. Standardized as SMPTE 348M this provides a 1.5 Gb/s data link.

Secure Digital (SD) Card

A non-volatile memory card format that is widely used in portable / hand-held devices, including digital cameras, tablet computers, smart phones, etc. SD cards are specified with speeds described in multiples of the standard CD data speed – 150 kB/s, and capacity.

The original SDSC (Standard Capacity) offer up to 2 GB storage and a bus speed of 25 MB/s. Next up SDHC (High Capacity) provides from 2 GB to 32 GB storage and support for FAT32 file systems (as is used on many PCs). SDXC introduced in 2009 supports capacities beyond 32 GB to 2TB and a maximum data speed of 300 MB/s. For yet more performance there is now Ultra Speed Bus. UHS-I can have a clock speed of 100 MHz, so handling 50 MB/s in 4-bit mode. UHS104 has a 208 MHz clock and can transfer 104 MB/s. UHS-II raises the transfer rates to a possible 156 MB/s (312 MB/s half duplex).

Currently the highest capacity on the market is a SDXC from SanDisk, offering 512 GB. This was introduced at the IBC 2014 trade show where many of the visitors and exhibitors are constantly seeking higher capacities and speeds to handle ever larger TV formats and higher frame rates.

Markings on the cards indicate their performance. A ‘C’ refers to a speed Class. The number in the big C is the minimum sustained transfer speed in MB/s; typically 2, 4, 6, 8, and 10 are used. Above that you will see a ‘U’ on the card. A ‘I’ in the U is for 10 MB/s UHS-I, and III for 30 MB/s.

SD cards have transformed video storage in both amateur and professional video cameras. Panasonic was an early adopter with its professional camcorders using P2 cards. Each card includes SD chips, a micro computer and RAID controller. There are no moving parts. There is no noise. It takes only tiny power and it is compact and robust – and a long way from tape and disk-based recording. P2 cards can read at 8x real-time for quick transfers to editing equipment. They can be used as edit stores in themselves.

See also: Flash memory, ING, P2, RAM

Website: aframe.com/blog, www.sdcard.org

Serial Digital Interface (SDI)

Serial Digital Interface carries uncompressed video, multiple tracks of embedded audio and ancillary data usually over the ubiquitous 75-ohm coax cable, terminated in a BNC connector. As the demands of television have grown so SDI has risen to the challenge to continue providing a reliable plug-and-play connection. Today there are many types to fit with the demands for bigger and faster video formats.

SDI SMPTE 259M – for SD 4:2:2 digital television, is based on a 270 Mb/s transfer rate. This is a 10-bit, scrambled, polarity-independent interface, with common scrambling for both component ITU-R BT.601 and composite digital video and four groups each of four channels of embedded digital audio. Most broadcast video equipment includes SDI which greatly simplifies its installation and signal distribution. It can transmit the signal up to 350 meters (depending on cable quality and connected equipment, specifically distribution amplifiers and routers).

HD-SDI is standardized in SMPTE 292M is for 4:2:2 HD television. The serial bit-stream runs at 1.485 Gb/s to carry up to 10-bit Y,Cr,Cb component video as well as embedded audio and ancillary data. The interface is also specified for fiber for distances up to 2 km.

3G-SDI (SMPTE 424M) operates at 2.97 Gb/s, twice the clock rate HD-SDI and is designed to carry high bandwidth HD television such as 1080/50P, 1080/60P, HD RGB, as well as 2K DI images.

6G-SDI (not yet standardized) operates at 5.94 Gb/s and can carry 4K at up to 30P.

12G-SDI (not yet standardized) operates at 11.88 Gb/s can carry 4K at up to 60P frame rate.

The higher bit rates can work over shorter lengths of coax and Fibre Optic versions can be used for the larger/faster frame-rate formats over longer distances.

See also: Dual link, Embedded audio, UHDTV, SDTV, SMPTE

Smart TV

A television set that includes an internet connection, some computing power and a UI to access the ‘Smart’ functions – including internet browsing. Popular uses include accessing ‘catch-up TV’ services such as Comcast’s Xfinity and the BBC’s iPlayer. Smart TVs now make up nearly 50 percent of the set population in the USA. However, the use of the internet beyond the catchup services is reported to be in decline, with the UI cited as a major cause.

SNMP

Simple Network Management Protocol is the Internet standard protocol developed to manage nodes (servers, workstations, routers, switches, hubs, etc.) on IP networks. It enables network administrators to manage network performance, find and solve network problems, and plan for network growth. SNMP works by sending Protocol Data Units (PDUs) messages to different parts of a network. Agents, SNMP-compliant devices, store data about themselves in Management Information Bases (MIBs) and return this data to the SNMP requesters.

USB

Universal Serial Bus – has been evolving. It is common to have four or six USB connectors on a PC or laptop computer. These are usually USB 2.0 (introduced in 2000), identifiable by the ports which are generally black. The maximum transfer rate is 480 Mb/s which offers potentially useful connectivity for media applications on PCs and Macs. It is very cheap and widely used for connecting PC peripherals. It is a PAN, and so the service provided to any one device depends on their specification and what other connected devices are doing. Actual speeds achieved for bulk data transfers are about 300 Mb/s – but this is likely to rise.

The newer (2008) USB 3 ports are generally blue. They add a new transfer mode called SuperSpeed working at up to 5 Gb/s, more than ten times faster than USB 2. It is also full duplex (USB 2 is half duplex) meaning it can both simultaneously transmit and receive at full speed – making a total of 10 Gb/s I/O. USB 3.1 was released in 2013 which doubled the top speed to 10 Gb/s, with full duplex.

See also: IEEE 1394