HDTV Guide Network Electronics

HDTV Guide

The increasing adoption of larger screens in the homes is now driving the new requirements for high quality content.

The next generation of cameras, servers and other signal sources will, in addition to todays HDTV standards, support 1080p qualities and beyond.

These qualities require more bandwidth than the 1.5 Gbps (SMPTE 292M) as we know today.

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HDTV Guide This guide is an introduction to some of the issues related to upgrading to HD infrastructures in broadcast operations.

When electronic television was first introduced, back in the early 30’s, it was with 4:3 picture format and very limited resolution (400+ lines). The film industry then introduced “wide screen” 16:9 (and wider) in the 50’s, and it’s just recently that the television industry could cope with the film innovation. It took 50 years!

After the introduction of colour TV, there was only one standard video resolution (known as Standard Definition, or SD). For many years this was good enough for viewing video programs on small TV sets.

However, over the last few years, a new generation of HDTVs, flat panels, plasma screens, and home projectors became available and affordable to the consumer.

People can now enjoy bigger, sharper and brighter pictures in their home than the smaller, boxy television sets of the past. …any format containing at least twice the standard definition format on both H and V axes is High Definition.

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Broadcasters are now seriously looking at transmitting HDTV to the home. Major investments and new design of infrastructures in the Broadcast operations and Production facilities is required, including studio set-ups and make-up.

High Definition (HD) is the next evolutionary step toward better video quality. HDTV supports many video formats with higher picture resolutions, all in the 16:9 aspect ration.

The Terrestrial networks, and their continuous fight for more bandwidth, is still to offer good quality HD content to the home. To be able to do so, new technologies and compression techniques are required to reduce the datarates involved. Since these technologies are not yet commercially available, HDTV over european terrestrial networks is expected no sooner than 2008.

World wide HDTV transmission overview

The world wide HDTV transmission overview (see table) gives an indication of the different resolutions used, and the distribution channel for delivering HDTV content to the home.

In Europe, some HDTV channels are already available over satellite.

Also major events, like the World Championship in football, was transmitted HD over satellite in some european regions.

USA: 1080/60i, 720/60P - 1 060 DTV/HDTV Stations On-Air (as of Oct. ‘03) 99.17% Coverage - HD available through Terresterial, Satellite and Cable Japan: 1080/60i BS-4b Satellite HDTV started from Dec. ‘00 (7 channels.

1080(60i), Terrestrial DTV has started from Dec. ‘03 China: 1080/50i is announced (Aug ’00) 3 major cities started test on-air from July ‘01. Official DTV starts from 2005 (66 citites) South Korea: 1080/60i Terrestrial HDTV test started Sep. ‘00. Simulcast started from Dec. ‘01. Digitalization completion by 2005 Australia: 1080/50i (or 576p) DTV/ HDTV started Jan. ‘01. DTV Official Kick Off at SMPTE ‘03

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Terms and Jargon used in HDTV Interlaced or Progressive In the interlaced world, each picture frame is displayed line-byline on the screen in two passes.

Each pass consists of half the alternating horizontal lines, which together are called a “field”. Two passes or two interlacing fields make a full frame. The rapid succession of each field to the next gives viewers a sense of

continuous motion through “persistence of vision”, and to the naked eye the image looks solid and whole. This interlacing of the picture is due to historical limitations on the cost of electronics and the available bandwidth for conventional TV broadcasts.

By progressively scanning the image every 50th/60th of a second rather than “interlacing” alternate lines, a smoother, more detailed image can be produced.

A progressively scanned picture is suited for viewing fine details and is also less susceptible to interlace flicker. Progressive scan differs from interlaced scan in that the image is displayed on a screen by scanning each line (1,2,3,4,5,6…) in a sequential order rather than an alternate order (1,3,5…2,4,6).

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Aspect Ratio

4x3 Aspect Ratio

Early motion picture film and television images adopted a 4:3 aspect ratio. That means any image recorded and displayed assumes an active picture area that is four units wide and three units tall. Since most of us move about in a horizontal world, our photographic images, particularly moving images, look better when they are wider than they are tall. When people walk through a room in the movies, they usually enter and exit horizontally.

– 4 units wide x 3 units high 1

2

3

4

1 2 3

Original 16:9 picture In HD the pixel aspect ratio is 1:1 compared to the SD where it is 4:3 and 16:9

Wide Screen Beginning in the early 1950’s, movie studios began adopting wider screens in order to compete with television. Wide screen productions boasted impressive aspect ratios exceeding 2:1.

Theater screens were twice as wide as they were tall and the images created for them had to match the display expectation.

Eventually, television adopted their own wide screen format with an aspect ratio of 16:9. Think of the legacy 4:3 aspect ratio as being 12:9 when compared to 16:9 wide screen. These days, we’re

16:9 picture shown in a 4:3 picture format

Why wide?

Since most of us move about in a horizontal world, our photographic images, particularly moving images, look better when they are wider than when they are tall.

likely to encounter one of the two aspect ratios and have the need to display them on a screen of the wrong type.

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Vertical and Horizontal Resolution The “vertical resolution” of NTSC/ PAL TV refers to the total number of lines (rows) scanned from left to right across the screen - but counted from Top to Bottom, or Vertically. This number is set by the TV ‘Standard’. This Vertical Resolution number is static – it doesn’t change.

Therefore, the Vertical Resolution is the same for ALL TV’s manufactured to meet a specified Standard.

The “horizontal resolution”, (number of vertical lines or columns) however, is variable.

The horizontal resolution of television, and other video displays, is dependent upon the quality of the video signal’s source.

As an example - the horizontal resolution of VHS tape is (about) 240 lines; broadcast TV (about) 330 lines, laserdisc (about) 420 lines; and DVD (about) 480 lines.

0

640

720

768

852

1280

DV NTSC

0

480p

F Active lines per frame (picture) (AL/F) E

1920

Common resolutions (by pixel count) 1:1 par

480i

PAL

480 576

720p 720

1080p, 1080i

1080

F Samples per active line (S/AL) E

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Resolutions in HDTV In general, as applied to television picture quality, ‘resolution’ would be more accurately stated as “limiting resolution”.

This references the point where individual (picture) elements are no longer discernable from adjacent elements. In other words, the TV’s resolution is “limited” to how finely detailed the displayed image can be, before the elements next to each other become too blurred to be distinguishable.

However, TV resolution can be described, measured and specified in different ways...

• The number of lines per (mm or inch) both vertically and horizontally.

• The number of line-pairs per (mm or inch) - vertically and horizontally.

• The number of lines per totaldisplay - Lines per Picture Height -LPH.

Resolution Samples per active line (S/AL)

Active lines per frame (picture) (AL/F)

EBU image sampling systems til HD Scanning/ frame rate

Samples per active line (S/AL)

Active lines per frame (picture) (AL/F)

“1280x720/P/50 (abbr.: 720/P/50)”

1280

720

“1920x1080/I/25 (abbr.: 1080/I/25)”

1920

“1920x1080/P/25 (abbr.: 1080/P/25)” “1920x1080/P/50 (abbr.: 1080/P/50)”

Frame rate, Hz

Corresponding SMPTE system nomenclature

50

Corresponds to SMPTE 296M

1080

“25 (50 Hz field rate)”

Corresponds to SMPTE 274

1920

1080

25

Corresponds to SMPTE 274

1920

1080

50

Corresponds to SMPTE 274

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Top US TV series move from 35 mm film to HD NETWORK

Show

Format

8 Simple Rules I’m with Her According to Jim Less than Perfect My Wife & Kids It’s All Relative George Lopez Hope & Faith Life with Bonnie

1080/24P 1080/24P 1080/24P 1080/24P 1080/24P 1080/24P 1080/24P 1080/24P 1080/24P

Yes Dear Still Standing Becker Joan of Arcadia Hack

1080/24P 1080/24P 1080/24P 1080/24P 60i/35

One Minute w/Stan Hooper Wanda at Large Luis Oliver Beene Bernie Mac Show

1080/24P 1080/24P 1080/24P 1080/24P 1080/24P

Whoopi Happy Family American Dreams

1080/24P 1080/24P 1080/24P

The Parkers Girlfriends Half & Half One on One All of Us Rock Me Baby Enterprise

1080/24P 1080/24P 1080/24P 1080/24P 1080/24P 1080/24P

Angel What I Like About You Reba Like Family Grounded for Life All About the Andersons

1080/24P 1080/24P 1080/24P 1080/24P 1080/24P 1080/24P

In North America, the dominant broadcast HDTV standards are 720p60 and 1080i60

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1080/24P = 1920x1080x24P

The European Broadcast Union has recently decided to support both 720p50 and 1080i50 HDTV formats.

HD Acquisition, news from the press Panasonic Camcorder By early 2007 Panasonic will deliver a new shouldermount camcorder that includes the ability to capture images at 24p frames per second.

As the first shoulder-mount camcorder in Panasonic’s P2 HD series, the multiformat AJ-HPX2000 features three native HD progressive 2/3in CCDs that support 17 HD and SD formats, including 1080i, 720p, 480i and 576i – Panasonic Press release Dec. 2006

Panasonic AJ-HPX2000

Sony Functions for HDC1000/1500 series camera Heads: • Improved standalone operation – RGB 4:4:4 output option, using Dual Link connection • Only available in 1080 modes (1080/24P,25P,50i, 60i), not available for 720p

HD in production … There are more than 100.000 Sony Professional High Definition camcorders and VTRs in use worldwide – Sony

Thomson GVG – Key Features

Thomson GVG

• Captures raw data directly from CCDs • Unique 4:4:4 RGB Dual Link FilmStream output • Native 16:9 or 2.37:1 aspect ratios without resolution loss using Dynamic Pixel Management™ technology • Patented Frame Transfer (FT) CCD technology • Mechanical shutter guarantees no vertical smear • Multiple format support: – 1080p @ 23.98-, 24-, 25-, and 29.97 frames per second (fps) – 1080i @ 50 and 59.94 Hz – 720p @ 23.98-, 24-, 25-, 29.97-, 50-, and 59.94 fps

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The HDTV infrastructure Non destructive signal path In Home Theaters, HDTV display is a direct-digital video connection of either the DVI or HDMI type (the two cable types are compatible; a DVI output on the DVD player may be connected to an HDMI input on the TV via a simple adaptor cable). With this type of connection, the data stays entirely in the digital domain. A source connected by analogue cabling must convert the digital data present on the DVD/source into an analogue TV signal, after which point the HDTV receiving

the video will re-digitize the signal for its own internal processing.

In a broadcast facility we are seeking the same benefits as with consumer connections. A direct-digital connection bypasses extraneous conversion steps, delivering exactly the bits encoded on the disc without conversion noise or filtering.

The next generation of cameras, servers and other signal sources will, in addition to today’s HDTV standards, support 1080P qualities and beyond. These qualities require more bandwidth than the 1.5 Gbps (SMPTE292M) as we know today.

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Dual Link The 1080p bit rates can be solved in a non-technical way by combining 2 channels of HD 1.5 Gbps.

This solution occupies two channels of HD and requires double cable connectors and interfaces to the equipment. I.e. it’s an expensive solution and not very flexible.

Dual Link for 1080p • Maintain Uncompressed Signals • Requires 2 x cable/connector • Requires 2 x equipment interfaces • Expensive solution

Single Link The new ”hype” in the broadcast industry is the 3 Gbps Single Link standard (SMPTE 424M). Still in its early days, the 3 Gbps interface is required in the market.

Single Link …

• allows for uncompressed transport of 1080p formats on single cable • allows for use of existing cable, connectors, patch panels and other passive elements in the signal path or infrastructure • Low latency

Applications • 1080p 50/60 transport over Single Link Cable • Replacement for dual link HD-SDI

• 3D HDTV • Digital Cinema • Slow motion capture The 3 Gbps interface has limited cable length as the major obstacle.

The availability for source and destination products are currently very limited (not present). The industry support for the interface is therefore not proved.

Both SMPTE and the ITU have completed standardization of a 3 Gbps SDI interface • SMPTE 424M (Physical interface) • SMPTE 425M (format mapping) • ITU-R BT 1120-3 part 4 2005

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3 Gbps and 1080p Introduction Why 1080p?

Production in 1080p has it’s advantages due to its ability to down­convert well to any other format for transmission, DVD mastering and other broadcast HD formats whilst maintaining the best possible master for archiving and future use.

Some of the benefits of 1080p production • Easy downscaling to multiple formats – Down conversion to 720p or 1080i is a process with limited loss of

quality • International standards – SMPTE/ITU • Program exchange expanding – 1080p/24 Universal Master • Film, feature, Drama, Sports – Benefit from same high quality standards

Bandwidth requirements for HDTV formats

500

1G

1.5G

1920 x 1080 p60

1920 x 1080 p50

1280 x 720 p60

1920 x 1080 i60

1280 x 720 p50 1920 x 1080 i50

625 Line SD

525 Line SD

0

2048 x 1080 p24

SMPTE 292M ITU-R BT.1120-3

SMPTE 259M

2G

2.5G

3G

Required bit rate to transmit HD

Spectrum Limits of 1920x1080x50P V

V

H

T

1920 x 1080 x 50p

V

H

T

1920 x 1080 x 50i

V

H

T

1920 x 1080 x 24p

H

T

1280 x 720 x 50p

Three-dimensional spectrum limits of 1920x1080x50P. It shows that all other formats are a subset.

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3 Gbps SDI Supported Formats Overview We find multiple HDTV formats that require bit rates above the current HD infrastructure (1.5 Gbps). Some of these are:

Picture Format

Signal Format

Frame Rate

1920 x 1080

4:2:2 (Y’C’BC’R)/10-bit

60, 60/1.001 and 50 Frames

(SMPTE 274M)

Progressive 4:4:4 (R’G’B’)/10-bit 4:4:4:4 (R’G’B’ + A)/10-bit 4:4:4 (Y’C’BC’R)/10-bit 4:4:4:4 (Y’C’BC’R + A)/10-bit

60, 60/1.001 and 50 Fields Interlaced

4:4:4 (R’G’B’)/12-bit

30, 30/1.001, 25, 24 and 24/1.001

4:4:4 (Y’C’BC’R)/12-bit

Frames Progressive

4:2:2 (Y’C’BC’R)/12-bit 1280 x 720

4:4:4 (R’G’B’)/10-bit

60, 60/1.001 and 50 Frames

(SMPTE 296M)

4:4:4:4 (R’G’B’ + A)/10-bit

Progressive.

4:4:4 (Y’C’BC’R)/10-bit

30, 30/1.001, 25, 24 and 24/1.001

4:4:4:4 (Y’C’BC’R + A)/10-bit

Frames Progressive

4:4:4 (X’Y’Z’)/12-bit

24 Frames Progressive

2048 X 1080 (Proposed 428M-3)

At NAB 2006, Network Electronics in cooperation with Gennum showcased the first working 3 Gbps Single Link router, the SL-3GHD1602-CP.

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3 Gbps Cable Length Considerations Cable EQ input The cable equalizer compensates for loss of signal amplitude and high frequencies caused by the cable.

To compensate for the cable loss, the cable equaliser characteristics are like a high-pass filter which compensates for the loss of high frequencies.

The amplitude quality of the cable equaliser is what determines the maximum cable length.

Cable Insertion Loss Cable insertion loss 0 -5

1505A 1694A

-10 -15 -20

According to Gennum, the technologies currently in use with a single equalizer section support cable lengths up to 70 meters for single coaxial cable links.

Gain (dB)

-25 -30 -35 -40 -45 -50 -55 -60 -65 -70 1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

Frequency (Hz)

By utilizing two sections of cable equalizers, 100 meters of cable length could be achieved.

Cable EQ Output Cable and equaliser insertion loss

100

50

0

-50 Equaliser gain -100

Net

Graphs provided by Belden.

Cable attenuation -150 1.0E+05

1.0E+05

1.0E+07

1.0E+08

1.0E+09

1.0E+10

Frequency (Hz)

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Data Re-Clocker A data re-clocker consists of a narrow-band PLL (Phase-Locked Loop) which regenerates a clock.

The regenerated clock is then used to re-clock the equalized data, and reduce the output jitter to levels which allow further processing of the data.

Reclocked Output

Cable Driver • The requirements for a 3 Gbps SDI cable driver are not significantly different from those for the existing HD-SDI interface: – Rise/fall time decreases from <270 ps to <110 ps – Return loss requirements are extended to include >10 dB for 1.5 GHz to 3 GHz

Summary • Single stage equaliser gives 70 meters with coax.

• Double stage equaliser gives 100 meters over existing HD infrastructure with coax.

Thanks to:

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Serial Digital Video over optical fibre Until now, SMPTE 297M has covered SDI up to 540Mbps over fibre, but now the standard is about to be extended to also include SMPTE 292M HD-SDI at 1483.5 and 1485Mbps as well as SMPTE 424M SDI signals at 2.967 and 2.97 Gbps bit rates. This shows the need to transport these signals over optical fibre having a standardised interface.

The trend of transporting higher bit rates is a challenge for coaxial cable based infrastructure. Even high quality coaxial cable like Belden’s 1694A will, when used for gigabit SDI bit rates, need signal regeneration after a length in the range of 100 meters. People are looking into new coding formats to re-use installed coaxial cable even for higher bit rates, but this has not been concluded.

For new installations, we can recommend deploying single mode optical fibres, as this will be a future proof solution without any limits in capacity.

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Quick summary • Fibre can be used for transporting signals over literally any distance • Coax: SD <300 meters between nodes • Coax: HD <100 meters between nodes • Galvanic isolation is needed • Coax: Hum & Noise (grounding problems) • Cable volume is low and lightweight • Easy to expand future capacity needs • Not necessary to deploy new cables, theoretical bandwidth of the fibre is ~100 Tbps • Digital Video Networks • No cable crosstalk

Today this thin fibre can transport 40 channels of uncompressed HD data.

1080p/3G-SDI Single Link Optical Transport • The “Ideal Transport” for 1080p – Reuse of current HD infrastructure – Economically feasible to implement – Similar performance characteristics to existing interfaces – Well known signal coding format for broadcast engineers – Benefit from optical fibres for longer distances – Low latency • International standards support – SMPTE 424M (physical interface) – SMPTE 425M (format mapping) – ITU-R BT 1120-3 part 4 2005

Diagram displaying the eye-pattern after optical to electrical conversion

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Synchronising your HD Infrastructure Synchronization of your broadcast system either if itâ&#x20AC;&#x2122;s SD or HD is necessary when more than one source of audio or video is being used. If the sources are not synchronised, incorrect colours or rolling pictures can show when transitions are made between sources.

A sync pulse generator will provide the synchronising signal to all devices (video and audio) that must lock to the main video program. This analogue composite reference video signal is bidirectional and called colour black, house black, or black burst video.

Tri-level Sync Tri-level reference sync could be considered synonymous to house black in that it is simply the reference synchronising information from the facilityâ&#x20AC;&#x2122;s master generator. Similar to black burst or colour black, you must use the proper tri-level sync to synchronise your sources in a HD

facility. For all the progressive and interlaced HD formats thereâ&#x20AC;&#x2122;s a reference sync. A HDTV Synch Generator provides the internal reference frequencies needed to support the most commonly used HDTV formats and related lower scan rate non-interlaced formats.

Some of these are:

HD Format

Frame Rate (frames per second)

1080i

30.00, 29.97, and 25.00 fps

1080p

30.00, 29.97, 25.00, 24.00, and 23.976 fps

720p

60.00 and 59.94 fps

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The tri-level sync would be carried on separate analogue distribution channels throughout the broadcast system. You can distribute the tri-level sync using an analogue video distribution amplifier or routing switcher.

SMPTE 240 standard Pulse start at the zero volts (specified black level) and first transitions negative, to -300 mV (+/- 6 mV). After a specified period, it transitions positive + 300 mV (+/- 6 mV), holds for a specified period and then returns to zero or black level.

This symmetry of design results in a net DC value of zero volts.

Without a DC component, the tri-level sync has a major advantage compared to bi-level sync (black burst). A bi-level signal introduces a DC component into the video sync signal. Tri-level sync eliminates the DC offset making signal processing easier.

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What now?

Driven by the consumers, HDTV will experience a rapid growth in the broadcast industry.

Standardisation committees and broadcast organisations are working hard to make sure the format jungle is “under control”.

Meanwhile, the manufacturing industry is eager to bring new product to market, within the standards if possible, outside if necessary to fulfil their commercial motivations For the broadcast operation, following the standards committees has always been safe and a wise strategy. In the adoption of HDTV, the consumer/ customer might not have the patience, they want good pictures on the big home theatre, and they want it now!

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Building infrastructures on existing installations is a step forward, but if new infrastructures are to be planned and designed, fibre networks should be taken seriously into consideration. How long will it take before the 3 Gbps infrastructure is out of date? Can coaxial cable handle bandwidths above these bit rates?

For long distance signal transport and future bandwidth needs, fibre is becoming more and more popular in new and current installations.

For more information please refere to Network Electronics’ Fibre Tutorial – can be downloaded from network-electronics.com.

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HDTV Glossary 3:2 Pull Down

the wide-screen format, it is not considered

3:2 pull down is a process by which

a high definition format. It is related to EDTV

manufacturers add six frames to film’s

and current DVD’s.

original 24-frames-per-second format so that it can work within the NTSC standard,

720p

which is 30 fps. This helps keep the action

720p means that the resolution of

from stuttering on your television.

the picture is 1,280 vertical pixels by 720 horizontal pixels and p stands

4:3

for progressive scanning. Progressive

4:3 is an aspect ratio of traditional squarish

scanning offers a smoother picture as 720

National Television Systems Committee

horizontal lines are scanned progressively

(NTSC) (PAL) TV screens; it stands for four

or in succession in a vertical frame that is

units of width for every three units of height.

repeated 30 times a second.

16:9

1080i

16:9 is an aspect ratio of movie screen

1080i means that the resolution of the

and widescreen DTV formats used in all

picture is 1920 vertical pixels by 1080

HDTV (High Definition TV) and some SDTV

horizontal pixels and i stands for interlaced

(Standard Definition TV); it stands for 16

scanning. Interlaced scanning is based on

arbitrary units of width for every 9 arbitrary

the principle that the screen shows every

units of height.

odd line at one scan of the screen and then all the even lines in a second scan.

24p Terminology for 24 full frames per second

1080p

digital video progressively captured. In most

1080p means that the resolution of

cases it refers to the HD picture format of

the picture is 1,920 vertical pixels by

1920x1080, though it is also used with

1,080 horizontal pixels and p stands for

1280x720 images as well. Often used to

progressive scanning. This format works

loosely describe a capture system that

on the same principle as 720p; the only

operates at 23.976P as well.

difference is that in this type there are more pixels and the resolution is better.

480p 480p means that the resolution of

AC-3

the picture is 852 vertical pixels by

The 5.1-channel sound system specified in

480 horizontal pixels and p stands for

the Digital HDTV Standard, also known as

progressive scanning. Although 480p is in

“Dolby Digital”. AC-3 delivers CD-quality

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digital audio and provides five full-

time period (usually a second). More

bandwidth channels for front left, front

exactly, it is a range of frequencies used for

right, center, surround left and surround

transmitting picture and sound information

right speakers, plus an LFE (low-frequency

from transmitter to your TV.

effect) subwoofer, for a total of 5.1 channels.

Addressable Resolution

Barn Doors A term used in television production to

The highest resolution signal that a TV or

describe the effect that occurs when a 4:3

monitor can accept. It is important to note

image is viewed on a 16:9 screen. When this

that while a particular device (Digital-HDTV)

happens, viewers see black bars on the sides

is able to receive the resolution, it may not

of the screen or “barn doors.”

be capable of displaying it.

Anamorphic video

Bit Rate Bit rate is measured as “bits per second”

Video images that have been “squeezed”

(bps) and refers to the rate at which the

to fit a video frame. These images must be

data is transmitted. The higher the bit rate,

expanded (un-squeezed) by the display

the more data is processed which usually

device. An increasing number of TVs employ

results to higher picture resolution or better

either a screen with 16:9 aspect ratio, or

sound quality.

some type of “enhanced-for-widescreen” viewing mode, so that anamorphic and

Codec

other widescreen material can be viewed in

Codec is a short term for “Coder-decoder.”

its proper proportions. When anamorphic

This device is used to convert analogue

video is displayed on a typical TV with

video and audio signals into digital format,

4:3 screen size, the images will appear

and vice versa, it can also convert received

unnaturally tall and narrow.

digital signals into an analogue format.

Aspect ratio

Compression

Aspect ratio is ratio of width to height of

Compression allows the delivery of more

a TV screen. It may be either traditional

programs in a single channel. It is an

squarish 4:3 ratio or 16:9 ratio of

electronic manipulation of digital data that

widescreen.

reduces and removes redundant and/or non-critical information in the digital picture

Bandwidth

and sound without noticeably degrading

Bandwidth, in general, means amount of

picture quality. One of the compression

information that can be carried in a given

methods is called MPEG-2.

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Deinterlacing The process of converting an interlaced-scan

DVI (Digital Visual Interface)

video signal (where each frame is split into

DVI is a standard that provides a high-

two sequential fields) to a progressive-scan

bandwidth, low-cost digital interface

signal (where each frame remains whole).

between a video source and a display device. It is capable of carrying

Dolby Digital (Dolby AC-3)

uncompressed unprotected high resolution

Dolby Digital, also called Digital 5.1 or AC-3,

supports real-time complex graphics displays

is a five-channel surround sound system

and user interfaces found in program guides

which delivers CD-quality digital audio and

and other interactive features for high

provides five channels of full frequency

definition television.

video transfers of HDTV signals, and

for front left, front right, center, surround left and surround right speakers, plus one

Frame rate

channel for LFE (low frequency effect)

The rate at which frames are displayed.

subwoofer. It is the official audio standard

The frame rate for movies is 24 frames per

for Digital TV and HDTV.

second (24 fps). In regular NTSC video, the frame rate is 30 fps, 25 for PAL.

Downconvert conversion from a higher resolution input

HDMI (High Definition MultiMedia Interface)

signal number to a lower resolution number.

HDMI assures that the best video signal is

A term used to describe the format

always sent from source (e.g., HDTV signal)

DTS

to the display (e.g., plasma television). It

Digital Theater Systems sound. Discrete 5.1

does this by allowing uncompressed video

channel surround system similar but not the

and multi-channel audio data to be input to

same as Dolby Digital. Dolby Digital is the

the display device through one single cable.

DTV standard, but DTS competes with it on

The need for multiple analogue connections

DVD and in the movie theaters.

for high-resolution audio and video are eliminated. Without a HDMI connection one

DTV (Digital Television)

would need 3 video connections for high

DTV stands for Digital Television. It refers to

definition video and 6 audio connections for

all digital television formats and standards

high-resolution audio.

established by the Advanced Television Systems Committee (ATSC). Two basic

HD-ready

DTV standards are HDTV (high-definition

Describes a television that is capable of

television) and SDTV (standard-definition

displaying one or both of the prescribed

television)

high-definition television formats (720p,

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1080i) but is not equipped with the requisite tuner/converter to receive digital signals.

HDTV (High-Definition Television)

NTSC (National Tele­vision Systems Committee) NTSC or National Television System Committee is the organization that

HDTV stands for High Definition Television.

develops technical standards for black-

With twice the vertical and horizontal

and-white television and color television.

picture resolution, the picture of HDTV is

NTSC established the 525-line (480 visible)

approximately twice as sharp as that of ­

analogue broadcast TV standard. The

PAL/NTSC. HDTV has widescreen aspect

new DTV digital broadcast standard will

ratio of 16:9 and Dolby Digital sound

eventually replace NTSC.

system. Currently used HDTV formats - 1080i and 720p both offer reduced motion

PAL

artifacts like ghosting and dot crawl.

Short for Phase Alternating Line, is a colour encoding system used in broadcast

Interlaced Scanning

television systems in large parts of the world.

Interlaced scanning is a method based on

Other common analogue television systems

the principle that the screen shows every

are SECAM and NTSC.

odd line at one scan of the screen and then all the even lines in a second scan. There

Pixel

are 25/30 frames shown per one second

Short for “picture element”. The smallest

and this can make larger screen flicker,

bit of data in a video image. The smaller the

which is the usual problem with interlacing.

size of the pixels in an image, the greater

However, LCD and plasma screens cannot

the resolution.

display interlaced signals and must first convert them to a progressive format and

Progressive Scanning

then they can display the transmitted

Progressive scanning is used by some

images.

HDTVs. Progressive scanning offers rather smooth picture as 720 or 1080

Letterbox

horizontal lines are scanned progressively

Letterbox refers to the image of a wide-

or in succession in a vertical frame that

screen picture on a standard 4:3 aspect ratio

is repeated 25/30 times a second. Some

television screen, typically with black bars

displays, for example LCD and plasma use

above and below. It is used to maintain the

progressive scanning method, while CRTs

original aspect ratio of the original source

may use progressive (e.g. in computer

(usually a theatrical motion picture of 16:9

monitors) or interlaced scanning method.

aspect ratio or wider).

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Refresh Rate

however, it does not reach the quality

The refresh rate for a monitor is measured

and resolution of HDTV. SDTV is based

in hertz (Hz) and is also called the vertical

on 480 lines of vertical resolution and in

frequency, vertical scan rate, frame rate or

both interlaced and progressively scanned

vertical refresh rate. The old standard for

formats.

monitor refresh rates was 50/60Hz, but a new standard developed by VESA sets the

Upconverting

refresh rate at 75Hz for monitors displaying

Process by which a standard definition

resolutions of 640x480 or greater. This

picture is changed to a simulated high-

means that the monitor redraws the display

definition picture.

75 times per second. The faster the refresh rate, the less the monitor flickers.

Widescreen Widescreen TV is the television with 16:9

Resolution

aspect ratio. 16:9 is the aspect ratio of movie

Resolution reflects the density of lines, and

screen and widescreen DTV formats used

dots per line which make up a visual image.

in all HDTV (High Definition TV) and some

It is measured by the number of pixels

SDTV (Standard Definition TV); it stands for

displayed. The level of resolution directly

16 units of width for every 9 units of height.

affects picture quality. Usually the higher number of lines and dots means also sharper and more detailed picture. Analogue TV has a little over 200,000 color pixels while HDTV, with 1080 vertical pixels and 1920 horizontal ones, has more than 2 million pixels creating the image.

Sampling This is the digital process by which analogue information is measured, often millions of times per second, in order to convert analogue to digital.

SDTV (StandardDefinition Television) SDTV stands for Standard Definition Television. The SDTV picture, having either in 4:3 or 16:9 aspect ratios, is better and of higher quality than the one of PAL/NTSC,

26 | network-electronics.com

Contributors: This document was created with reference to: Sony Broadcast & Professional Panasonic Broadcast HDTV forum Thomson Grass Valley Gennum BBC Avid Technologies John GS Ive, Ivetech Network Electronics

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