AUDIO VIDEO TERMINOLOGY [back to top]
100 Base-T is an Ethernet transmission standard. The "T" stands for
unshielded twisted-pair wire, or UTP.RJ 45 and RJ11 telephone jacks and four
pair UTP telephone wire are specified for interconnecting nodes to the LAN. It
operates at a transmission rate of 100Mbps.
1080i vs 1080p
There has been a lot of concern and confusion over the difference between 1080i and 1080p. This stems from the inability of many TVs to accept 1080p. To make matters worse, the help lines at many of the TV manufacturers (that means you, Sony), are telling people that their newly-bought 1080p displays are really 1080i. They are idiots, so let me say this in big bold print, as far as movies are concerned THERE IS NO DIFFERENCE BETWEEN 1080i AND 1080p. See, I did it in caps too, so it must be true. Let me explain (if your eyes glaze over, the short version is at the end).
For clarification, let me start by saying that there are essentially no 1080i TVs anymore. Unless you bought a CRT based TV, every modern TV is progressive scan (as in LCD, Plasma, LCOS, DLP). They are incapable of displaying a 1080i signal as 1080i. So what we’re talking about here mostly applies to people with 1080p native displays.
Movies and almost all TV shows are shot at 24 frames-per-second (either on film or on 24fps HD cameras). All TVs have a refresh rate of 60Hz. What this means is that the screen refreshes 60 times a second. In order to display something that is 24fps on something that is essentially 60fps, you need to make up, or create new frames. This is done using a method called 3:2 pulldown (or more accurately 2:3 pulldown). The first frame of film is doubled, the second frame of film is tripled, the third frame of film is doubled and so on, creating a 2,3,2,3,2,3,2 sequence. It basically looks like this: 1a,1b,2a,2b,2c,3a,3b,4a… Each number is the original film frame. This lovely piece of math allows the 24fps film to be converted to be displayed on 60Hz products (nearly every TV in the US, ever).
This can be done in a number of places. With DVDs, it was all done in the player. With HD DVD, it is done in the player to output 1080i. With Blu-ray, there are a few options. The first player, the Samsung, added the 3:2 to the signal, interlaced it, and then output that (1080i) or de-interlaced the same signal and output that (1080p). In this case, the only difference between 1080i and 1080p is where the de-interlacing is done. If you send 1080i, the TV de-interlaces it to 1080p. If you send your TV the 1080p signal, the player is de-interlacing the signal. As long as your TV is de-interlacing the 1080i correctly, then there is no difference. Check out this article for more info on that.
The next Blu-ray players (from Pioneer and the like) will have an additional option. They will be able to output the 1080p/24 from the disc directly. At first you may think that if your TV doesn't accept 1080p, you'll miss out on being able to see the "unmolested" 1080p/24 from the disc. Well even if your TV could accept the 1080p/24, your TV would still have to add the 3:2 pulldown itself (the TV is still 60Hz). So you're not seeing the 1080p/24 regardless.
The only exception to that rule is if you can change the refresh on the TV. Pioneer's plasmas can be set to refresh at 72 Hz. These will take the 1080p/24, and do a simple 3:3 pull down (repeating each frame 3 times).
What this all means is this:
- When it comes to movies (as in HD DVD and Blu-ray) there will be no visible difference between the 1080i signal and the 1080p signal, as long as your TV correctly de-interlaces 1080i. So even if you could input 1080p, you wouldn't see a difference (because there is none).
- There is no additional or new information in a 1080p signal from movie based content.
- The only time you would see a difference is if you have native 1080p/60 content, which at this point would only come from a PC and maybe the PS3. 1080p/60 does have more information than 1080i/30, but unless you're a gamer you will probably never see native 1080p/60 content. It is incredibly unlikely that they will ever broadcast 1080p (too much bandwidth) or that 1080p/60 content will show up on discs (too much storage space and no one is using it to record/film).
So all of you people who bought 1080p displays only to be told by the companies that you had bought 1080i TVs, relax. The TV will convert everything to 1080p. Now if you bought a TV that doesn't de-interlace 1080i correctly, well, that's a whole other story.
The DVD format is specially designed to support widescreen displays. Widescreen
16:9 video can be stored on the DVD disc in anamorphic form, meaning the picture
is squeezed horizontally to fit the standard 4:3 rectangle, and then unsqueezed
This anamorphic squeezing
results in less of the picture being wasted on the black letterbox mattes. DVD
has a frame size designed for 1.33 display, so the video still has to be made to
fit, but because it's only squeezed horizontally, 33% more pixels (25% of the
total pixels in a video frame) are used to store active picture instead of
black. Anamorphic video is best displayed on widescreen equipment, which
stretches the video back out to its original width.
Anamorphic video can be
converted by the player for display on standard 4:3 TVs in letterbox or pan
& scan form. If anamorphic video is shown unchanged on a standard 4:3
display, people will look tall and skinny as if they have been on a crash diet.
The setup options of DVD players allow the viewer to indicate whether they have
a 16:9 or 4:3 TV.
The ratio between the horizontal measurement and vertical measurement of a TV
screen. Standard NTSC televisions are built with a 4:3 aspect ration, while HDTV
systems are built to a 16:9 ratio. Keep in mind however, that not all theatrical
movies are filmed in 16:9 (or 1.78 aspect ratio). Many movies are filmed in
1:85, 2.15 or 2.35 widescreen. Movies filmed in an aspect ratio greater than
16:9 will result in black bars on the tops and bottom of the screen on a
widescreen television. The higher the ratio, the wider (relatively) the screen.
The loss of signal power during transmission. Usually a concern when a signal is
transmitted over a long distance.
AWG (American Wire
Measurement of the diameter of a wire or cable. Gauge is a unit used to measure
wire thickness. The smaller the number, the thicker the wire. (i.e. 10 gauge
wire is much thicker than 16 gauge wire). Typically, is it desirable to have the
lowest gauge speaker wire possible. Around 12 gauge is ideal, above 16 gauge is
not recommended for serious home theater applications.
The transmission capacity of a cable or other media. Usually measured in bits
per second or in cycles per second (hertz). A common analogy to bandwidth is a
water pipe the bigger the pipe (bandwidth) the more water that can flow through
it per unit of time.
Bi-polar refers to speakers with drivers that are fired in two different
directions, but are in phase causing an increase in bass output. I this type of
speaker the drivers can be in the front and back of the speaker, side firing, or
at 90º angles from one another. There are also speakers which function as both
bipolar and dipolar. This can be adjusted using a switch.
Bi-wiring refers to separate wire runs from a common amplifier output to two
different inputs on the same speaker. This requires a speaker specifically
designed with bi-wiring in mind as the speaker's passive crossover must be
designed to allow this. And the speakers must have two sets of external binding
posts connected by removable jumpers or "bus bars."
Bps (bits per second):
A measurement of bandwidth. This is the number of data bits that can be carried
over a network in a second. Often measured in thousands of bits per second
(kilobits per second Kbps) or millions of bits per second (megabits per second
A method of transmitting signals where several data signals are modulated onto
different frequencies and carried on the same cable or network medium. Compare
A high-speed Internet access device that uses the coaxial cable network of cable
television providers to connect a home PC or LAN to the Internet over
frequencies unused by television services.
(CAT-5): A performance rating for UTP wiring that is suitable for telephone and
Ethernet networks up to 100 Mbps, as well as ATM data networks up to 155 Mbps.
See also UTP.
Closed-circuit TV, an in-home video surveillance network.
Shielded cable that you can use to carry television signals or data within a
network. Coaxial cable typically consists of a center conductor, a layer of
insulation, another conductor wrapped around the insulation, and an outer layer
of shielding and jacketing. Coaxial cables used in home video applications are
designed with a 75 ohm impedance, and are rated according to their bandwidth
capacity. The most commonly found coaxial cables are RG-59 and RG6.
The baseband video signal output of a VCR, DVD player, or other video source
component Composite video utilizes one (RCA-jack type) cord to transmit all
A video transmission method. Better than composite video and s-video, equal to
RGB video. Component video uses three (RCA-jack type) cables to distribute the
red, blue and green portions of a video transmission separately. Component video
is typically used with DVD players and HDTV systems.
A plastic or metal pipe that is used to contain cable runs. It is often
installed empty into new homes to allow easy running of new cables in the
A crossover is a system of filters designed to divide audio bandwidth between
each individual driver in each individual speaker.
A dB is a unit of measure of signal strength, usually the relation between a
transmitted signal and a standard signal source. Every 3 dB = 50% of signal
strength, so therefore a 6 dB loss = a loss of 75% of total signal strength.
The point of interconnection between telephone company facilities and your home
wiring. The demarcation point ("demark") shall be located on the
subscriber's side of the telephone company's protector, or the equivalent
thereof in cases where a protector is not required. In most cases this point
also delineates the responsibility for the network. Everything inside of the
demarcation point is usually the responsibility of the homeowner.
Digital subscriber line
A new data-connection method that allows high-speed Internet connections and
other network connections over a standard telephone line. Variants of DSL, such
as asymmetric digital subscriber lines, are identified by a preceding initial
(ADSL in this case).
Dipolar refers to speakers with drivers that are fired in two different
directions and are in reverse phase causing a cancellation of sound waves in
front of the speaker. This is usually done in rear speakers that are wall
mounted. The front of the speaker is aimed at the listening area, which causes
all of the sound to bounce off the walls before it is heard. This makes it
almost impossible to determine where the speaker is, creating a true surround
In a video network, this is the panel that concentrates all broadband video
signals from antennas, cable TV feeds, and in-home video sources and distributes
them to outlets throughout the house. Often it also includes a built-in signal
Dolby Digital (AC-3) is an advanced perceptual coding technology for
transmission and storage of up to five full-range channels, plus a supplemental
bass-only effects channel (referred to as a .1 channel due to the smaller number
of bits needed for the information), in less space than is required for one
linear PCM coded channel on a compact disc. Dolby Digital is a more powerful and
flexible coding system than AC-2 and provides a feature set including -- 1) down
mixing for optimal reproduction in mono, stereo, and Pro Logic compatible
configurations as well as full 5.1 channel sound; 2) carriage of dynamic range
and dialog level control information to decoders; and 3) operation over a wide
range of bit rates. Dolby Digital is being used on the audio tracks on DVD, and
is the audio standard on the new high definition television (HDTV) system which
went into operation in the United States in 1998.
Dolby Digital EX:
Dolby Digital Surround EX adds a center rear surround channel to the 5.1-channel
format, providing a new tool for delivering greater sonic reality and excitement
to the audience.
DSP Digital Signal
These are audio effects added on-the-fly to sounds by a receiver or amplifier.
They usually consist of echo and reverb effects labeled "jazz, theater,
DSS Direct Satellite
A DSS system will use at least one small satellite dish (either 18" round
or 24" oval) and a receiver with a removable access card (similar to the
size of a credit card). DSS systems provide you with hundreds of channels to
choose from. And because the signals are all digital, DSS systems are capable of
delivering high quality video and CD quality audio. With the right equipment, it
is also possible to receive HDTV signals over satellite.
Digital Theater Systems is an international, digital technology company
specializing in multi-channel audio for entertainment. Founded in 1993, DTS
quickly became the leading provider of premium, discrete, multi-channel audio.
DTS Digital Surround is an encode/decode system that delivers six channels (5.1)
of master-quality, 20-bit audio. In the encoding process, the DTS algorithm
encrypts six channels of 20-bit digital audio information in the space
previously allotted for only two channels of 16-bit linear PCM. Then during
playback, the DTS decoder reconstructs the original six channels of 20-bit
digital audio. Each of these six channels is audibly superior to the 16-bit
linear PCM audio found on conventional compact discs.
The new DTS-ES discrete 6.1 format employs a new, proprietary technology for the
playback of discrete, 6.1-channel content from DVDs and CDs. The additional
channel over 5.1 audio is a rear center channel. In addition to DTS-ES discrete
6.1 decoding, the new DTS-ES program includes the introduction of the DTS-ES
Matrix 6.1 surround decoding format, which offers backward compatibility with
existing ES matrix-encoded content, and DTS Neo:6, which is a matrix technology
that derives up to 6.1-channel playback from conventional, stereo program
A high-fidelity audio storage medium with flexibility in the numbers of
channels, sampling frequencies, wordlengths and other features such as video
elements; DVD-Universal players can play both DVD-Video and DVD-Audio discs.
Digital Television. DTV is composed of three separate standards: HDTV 1080i
(1080 lines of resolution, 16:9 aspect ratio); HDTV 720p (720 lines of
resolution, 16:9 aspect ratio); and SDTV (480 lines of resolution, 16:9 or 4:3
The U.S. Congress has
mandated a change from the current NTSC (analog) television broadcasting
standard to DTV (digital) broadcasting. The Federal Communications Commission
has established a schedule for the introduction of DTV. Most Americans are
scheduled to have access to DTV by 1999 and everyone in this country is
scheduled to have DTV access by the year 2002. At the end of the transition
period -- which is now scheduled for December 31, 2006 -- broadcasters will be
required to surrender their analog channels to the federal government. This will
be the end of standard NTSC broadcasts.
Digital Video Disc or Digital Versital Disc. DVD has the same physical
dimensions of a CD; however it can hold much more information. DVD aims to
encompass home entertainment, computers, and business information with a single
digital format, eventually replacing audio CD, videotape, laserdisc, CD-ROM, and
perhaps even video game cartridges. DVD has widespread support from all major
electronics companies, all major computer hardware companies, and all major
movie and music studios. With this unprecedented support, DVD has become the
most successful consumer electronics product of all time in less than three
years of its introduction.
Some features of DVD
include: Up to 8 hours of high-quality digital video on one disc, support for
both widescreen and standard formats on the same disc, up to 8 tracks of
multi-channel digital audio (for multiple languages, DVS, etc.), up to 32
subtitle/karaoke tracks, automatic "seamless" branching of video (for
multiple story lines or ratings on one disc), up to 9 camera angles (different
viewpoints can be selected during playback), menus and simple interactive
features (for games, quizzes, etc.) and much more.
Digital Visual Interface. A data transmission port which supports up to 5
Gigabits/sec speed. Bandwidth of 2.2 Gigabits/sec. is required to support
uncompressed HD video transmission. With bandwidth of up to 5 Gbps for a single
DVI link, compared to the 400 Megabits/sec. supported by IEEE 1394, DVI is the
only digital interface capable of accommodating uncompressed digital data such
as HD video. DVI also has the bandwidth to support higher audio fidelity, such
as more channels of surround sound or 96 KHz sampling rates, as well as higher
video resolution such as 1080p-ensuring no risk of long-term obsolescence.
A local area network (LAN) used for connecting computers, printers,
workstations, servers, terminals, etc within the same building or campus. It
operates over twisted wire or coaxial cable the theoretical limit for Ethernet,
measured in 64 byte pockets, is 14,800 packets per second (PPS). By comparison,
Token Ring is 30,000. Ethernet specifies a CSMA/CD (Carrier Sense Multiple
Access with Collision Detection). The most common variation of Ethernet found in
home networks is the 10 Mbps lOBase-T variant, but dozens of other variations
exist with speeds up to 1000 Mbps.
A new high-speed data communications protocol most often used for connecting
digital video systems to computers. Future uses are envisioned to expand the
role of FireWire to include whole-home data, video, and audio networks. Also
known as IEEE 1394.
Television. It is the most life-like picture you can get with the sole exception
of looking out a window. HDTV offers wider pictures with greater detail and the
clarity of motion pictures. Compared to standard television (NTSC), the true
HDTV image has twice the luminance definition - vertically and horizontally -
and is twenty-five percent wider. Standard television aspect ratio is 4:3 - the
HDTV aspect ratio is 16:9. The 16:9 ratio is much closer to the average
widescreen image shown in movie theaters. However, the biggest difference
between NTSC and HDTV is its clarity. True HDTV pictures are composed of 1080
active lines (1125 total whereas current standard television pictures are
composed of only 480 active lines (525 total). The lines that make up standard
television pictures are clearly visible, but HDTV lines are not at all
noticeable. The fine-grained HD picture contains five times more information
than does the standard television picture and is accompanied by multi-channel,
Dolby Digital audio.
Networking Association (HomePNA):
An adaptor that converts computer data to transmit over standard telephone
Resistance to the flow of current in an alternating current circuit measured in
ohms. Most speakers have an 8 ohm impedance rating.
The part of the light spectrum just below the visible portion. Often used for
wireless networked devices and remote controls in a home.
Interconnects are a generic term for all of the audio and video cables that
connect your system together. Cables are not accessories but components, as
critical to your system's performance as your speakers or monitor.
LAN (local area
A computer data communications network used within a limited physical location,
like a house. Most home LANs utilize the Ethernet protocol.
Low Frequency Effects. These are the very deep booming bass sounds recorded into
a Dolby Digital or DTS audio track. They are typically reproduced by the
subwoofer in your home theater speaker system, however if a subwoofer is not
present in the system, most receivers will attempt to reproduce these sounds
through your main front speakers. Because it is not essential to the soundtrack,
the LFE track is identified as the ".1" in a 5.1 digital audio
recording. Soundtracks recorded as 5.0 Dolby Digital do not include a LFE track.
Lines of Horizontal
Lines of horizontal resolution are often confused with scan lines. The two are
totally different things, be careful when shopping for equipment. Lines of
horizontal resolution refer to visually resolvable vertical lines per picture
height. In other words, it's measured by counting the number of vertical black
and white lines that can be distinguished an area that is as wide as the picture
is high. Lines of horizontal resolution applies both to television displays and
to signal formats such as that produced by a DVD player. Since DVD has 720
horizontal pixels (on both NTSC and PAL discs), the horizontal resolution can be
calculated by dividing 720 by 1.33 (for a 4:3 aspect ratio) to get 540 lines. On
a 1.78 (16:9) display, you get 405 lines. In practice, most DVD players provide
about 500 lines instead of 540 because of filtering and low-quality
digital-to-analog converters. VHS has about 230 (172 widescreen) lines,
broadcast TV has about 330 (248 widescreen), and laserdisc has about 425 (318
widescreen). Scan lines, on the other hand, measure resolution along the y axis.
DVD produces 480 scan lines of active picture for NTSC and 576 for PAL. The NTSC
standard has 525 total scan lines, but only 480 to 483 or so are visible. (The
extra lines are black and are encoded with other information). Since all video
formats (VHS, LD, broadcast, etc.) have the same number of scan lines, it's the
horizontal resolution that makes the big difference in picture quality.
Low Noise Block filter. The LNB receives the signals bouncing off the satellite
A device that converts a computer's digital signals into analog tones that can
be carried over a telephone network. The name comes from the function, which is
to MODulate and DEModulate these signals.
The process of changing the electrical properties (such as frequency) of an
signal to facilitate carrying it over a network. Signals are often modulated to
different frequencies to allow multiple signals to be carried over a single
Network Interface Card
A device that connects to an internal bus in a PC, which provides an interface
between the computer and the LAN.
National Television System Committee. In 1953 the NTSC devised the NTSC
television broadcast system. NTSC is also commonly used to refer to one type of
television signal that can be recorded on various tape formats such as VHS.
The NTSC standard has a
fixed vertical resolution of 525 horizontal lines stacked on top of each other,
with varying amounts of "lines" making up the horizontal resolution,
depending on the electronics and formats involved. There are 59.94 fields
displayed per second. A field is a set of even lines, or odd lines. The odd and
even fields are displayed sequentially, thus interlacing the full frame. One
full frame, therefore, is made of two interlaced fields, and is displayed about
every 1/30 of a second.
Ohm is the unit used to measure the resistance presented by a loudspeaker when
it is introduced a signal by an amplifier. (The word Ohm comes from German
physicist Georg Simon Ohm, 1787-1854). Conventional wisdom makes an 8 ohm
loudspeaker load the most acceptable because it "protects" the
amplifier from delivering too much current. A 4 ohm loudspeaker can encourage a
marginally designed amplifier to deliver more current than it comfortably can.
All speakers in your home theater system should have the same Ohm rating.
A device that allows the interconnection of home runs of data or phone cabling
at a central distribution point.
Pulse Code Modulation. PCM is a digital scheme for transmitting analog data. The
signals in PCM are binary; that is, there are only two possible states,
represented by logic 1 (high) and logic 0 (low). This is true no matter how
complex the analog waveform happens to be. Using PCM, it is possible to digitize
all forms of analog data, including full-motion video, voices, music, etc.
Pink noise is noise that has equal energy in each octave.
A common language or specification used by devices communicating over a network.
A method for securing cables in a patch panel or outlet. The wire is placed over
a metal clip, and then punched down (with the appropriately named punchdown
tool) to penetrate the wire's insulation and provide an airtight contact.
RF (radio frequency):
The segment of the electromagnetic spectrum below visible light, used for both
wireless transmission of data and for transmitting modulated signals over cable.
A type of coaxial cable with an 18-gauge center conductor. It may be
dual-shielded, which means it has a layer of foil and a layer of braid, or
quad-shield, which means it has a second layer of foil and another layer of
braid on top of the second foil layer. RG-6 can carry signals up to 2GHz.
Satellite systems typically use signals in the range of 950MHz to 1.5GHz.
A video transmission method. A video transmission method. Better than composite
video and s-video, equal to component video. RGB video uses one 15 pin video
cable (this is the same video cable and distribution method used in computer
monitors) to distribute the video signal. Aside for PC's, RGB video is typically
found on HDTV and DBS satellite systems.
A six conductor modular jack that is typically wired for four conductors. It is
the most common telephone jack in the world.
The standard eight-position modular jack used in data networks. SACD (Super
Audio Compact Disc) A standard for high-density storage of two-channel CD and
two-channel and multi-channel SACD audio recordings. SACD recordings use 1-bit
Direct Stream Digital (DSD) coding.
A protective layer in a cable that prevents electromagnetic interference from
A device used in coaxial video networks either to split a single cable's signal
onto several cables or to combine the signals from several cables onto a single
one. When used to split signals, a splitter/combiner introduces a certain amount
of attenuation to the signal (usually listed on the splitter).
Structured Wiring is the backbone of a true high-speed connected home. It
contains two CAT 5e and two RG6 quad shield cables that run from every room to a
central location in the house. This enables the homeowner to connect high-speed
internet, satellite, cable TV, phone, fax, control, video, and network all the
PC's in the house, in every room in the house.
Super VHS. Better than standard VHS, not as good as DVD. An S-VHS recorder will
allow you to record programs in up to 480 lines of resolution (a standard VHS
will only record/play 240 lines of resolution. S-VHS VCRs will allow you to play
standard VHS tapes. Also, a Super-VHS VCR will have at least one S-Video output
A video transmission method. Better than composite video, not as good as
component video. S-video separates luminance (black and white information) and
chrominance (color information) signals. An s-video cord slightly resembles a
computer PS-2 cable.
A subwoofer is a (usually powered) speaker which produces very deep booming bass
sounds. Subwoofers are responsible for reproducing the LFE track in a 5.1 Dolby
Digital or DTS soundtrack. They are typically a cube shape with a large single
woofer either pointing directly at the ground or directly at the listener.
Usually, subwoofers are placed in the corner of the room. Ideally, a subwoofer
should be placed where it is impossible to determine the direction of where the
sound is coming from.
A device that prevents damage to electrical or electronic equipment by isolating
it from unexpected rises in current or voltage (like lighting strikes).
THX Surround EX:
Establishing a new benchmark for multi-channel sound, Lucasfilm THX has
announced THX Surround EX a home theatre application of the cinema surround
sound technology that made its theatrical debut with the opening of Star Wars:
Episode I The Phantom Menace. THX Surround EX is an enhancement to digital sound
that decodes a back surround channel in a film soundtrack allowing for dramatic
360° surround sound effects that are smoother and more accurately placed either
directly behind or directly beside a viewer.
Cabling, most often used for telephone and data networks, in which individual
pairs of wire are twisted around each other to reduce electrical interference.
See also UTP.
An IR or RF remote control that can be programmed to control multiple devices. A
"learning" universal remote control can be taught control signals from
just about any other remote.
Noise that has equal energy at each frequency.
A television with an aspect ratio of 16:9.
Another term for component video.