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- HDTV Glossary
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The following are some common HDTV and audio/video terminology
that will help you when choosing a HDTV television, set-top box
or satellite receiver.
8VSB/QAM Tuner-
8VSB or eight level vestigial sideband is the chosen standard to
over the air terrestrial broadcasts of HDTV signals. HDTV
broadcasters utilize UHF frequencies to broadcast their signals
over the air. QAM is the chosen HDTV transmission standard for
digital cablevision.
Aspect Ratio-
The aspect ratio of a television refers to its width relative to
its height. For a standard 4:3 television, for every inch of
width, there is 3/4" of picture height. This gives is the
squarish appearance. For a 16:9 wide screen HDTV television, the
picture is nearly twice as wide as it is high. Wide screen sets
are designed to eliminate or greatly reduce the letterbox effect
(black bars on the top & sides)
5.1 Surround
Sound- This is the current generation of
multi-channel surround sound that includes 6 channels of sound,
including 5 full frequency independent channels of discrete audio
(front right&left, rear right&left, center)and one separate .1
channel (20-20 000Hz) for Low Frequency Effects (LFE), which is
directed at your subwoofer. With 5.1 surround, the rear surround
speakers are now in stereo, versus mono for Dolby Pro-logic. This
translates into a much more realistic sound quality. The two most
common 5.1 surround formats include Dolby Digital, or AC-3 and
DTS or Digital Theater Sound.
6.1 Surround
Sound- The next generation of digital surround
sound is known as 6.1. This adds to the 5.1 experience by adding
a new rear surround center channel, which works with the rear
left and right surround channels to produce more realistic sound
effects. In order to receive 6.1 surround sound, you need a 6.1
capable receiver (Dolby Digital EX/DTS ES) and also a 6.1 encoded
source, such as a DVD. At the moment, very few sources are 6.1
encoded, so your 6.1 receiver will automatically fall back to 5.1
or pro-logic mode, depending on the source material.
Audio
Inputs/Outputs- This refers to the amount of
inputs and outputs on a device. There are normally more audio
outputs than video outputs.
BBE- This
refers to a sound enhancement circuit designed to clarify and
enhance mid to high range audio to create clear crisp dialog from
a television's internal speakers.
Bitrate- The
binary digital rate is the number of bits used to express the
sound frequency of an audio broadcast.
Center
Channel- The center channel in a home theater
setup is the center speaker designed to replace your television's
front speakers for mid to high range dialogue. If you have no
center channel, you may be able to use your television's speakers
depending on the functionality of your audio receiver.
Comb Filter-
This is a filter built into televisions that is designed to
improve resolution and picture quality by reducing objectionable
color patterns. low to mid line televisions use a glass comb
filter, while higher end televisions use a digital comb filter
which greatly enhances resolution.
Component Video
Inputs- Component video separates the video
signal into 3 distinct streams (red,green and blue), in which the
video signal is carried via three individual cables using RCA
type jack connections. There are two types of component video,
Y,Cr,Cb (normal interlaced DVD players) and Y,Pr,Pb(Progressive
scan DVD players,HDTV decoders and DTV inputs on televisions)
Component video is designed to bypass the comb filter and NTSC
decoder , which increases color resolution (nearly 500 lines) and
fidelity and reduces the noise in the color signal. Component
video works in conjunction with digital audio connectors either
coaxial or optical, which are standard on nearly all DVD
players.
Composite
Video- A standard RCA type video connection that
allows an interlaced video signal with a maximum resolution of
330 lines.
De-interlacing- This involves
assembling pairs of interlaced fields into one progressive frame,
1/60th of a second in length and showing it at least twice to use
up the same amount of time as two fields.
Digital Audio
Inputs/Outputs- The digital audio jacks on a
component that are either coaxial or optical that allow a digital
audio signal to pass.
Digital
Output- A pure digital audio signal output that
allows for a digital connection. The output comes in either a
coaxial cable (RCA type)or a TOSLink optical cable. Digital
outputs provide less noise and interference than any other type
of connection.
Digital Light Processing
(DLP)- This is a line of projection televisions
that provide premium quality picture quality without the use of a
cathode ray tube. The projectors use a digital micro mirror
device (DMD) to produce the images, which are then enlarged to
fill the screen. The DMD device has more than 1.3 million tiny
mirrors that are used to create the images in the same manner as
pixels are used in cathode ray tube devices. DLP equipped
televisions typically have a higher lumen and contrast
ratios.
Dolby Digital-
A well recognized multi-channel perceptual coding scheme,
introduced by Dolby Labs and initially known as AC-3(Audio Coder
3). Dolby Digital was introduced into movie theaters in June 1992
as Dolby Stereo Digital. Dolby's earlier coding scheme, known as
Dolby Surround or Pro-Logic is a single band limited surround
channel with a range between 100 and 700Hz. In comparison, Dolby
Digital offers a full dynamic range on all five main channels of
3-20 000Hz. On Laser discs and DVD's, the Dolby Digital scheme is
carried on the right analog FM track. The left analog FM track
usually carries the mono version of the soundtrack. Perceptual
coding has been developed to decode the digital audio and
eliminating the data that we cannot hear. The Dolby Digital
channels are discrete, unlike Pro-logic so they cannot interfere
with one another or bleed to an adjacent channel. The Dolby
Digital signal is fed into the audio receiver via digital coaxial
or optical cables.
Dolby Digital
EX- This is the next generation of Dolby Digital
surround sound and incorporates 6.1 discrete channels, adding in
a new rear surround center channel. This extra rear surround
channel works with the usual left and right surround channels to
produce an intensified realism that is designed to draw you even
further into the action. In order to receive the 6. channels, you
will need a Dolby Digital EX receiver and also 6.1 source
material, such as a 6.1 encoded DVD.
Dolby
Pro-Logic- The older Dolby Pro-logic coding
scheme is a matrixed system in which the four channels of
information(left,right,center,surround) are folded into two
discrete channels so they can be encoded onto the source material
such as a broadcast,VCR,DVD or laser disc. The Pro-logic
processor then extracts the four channels of data from the two
encoded channels and directs them to the speakers. The rear
surround channel is divided over two speakers, however it is a
mono signal. Pro-logic II is a variation of the original scheme
which allows more power and presence to the surround field.
Digital Theater Sound
(DTS)- DTS is another popular digital 5.1
surround scheme developed by MCA/Universal and Steven Spielberg.
Similar to Dolby Digital, the encoded DTS scheme is passed to the
receiver via the digital coaxial or optical cables. It is
designed to filter the audio signal into frequency bands which
match the perceptual bands of human hearing.
Digital Theater Sound ES (DTS
ES)- DTS introduced the first next generation 6.1
surround sound scheme, adding in a new rear surround center
channel to produce more stunning and realistic sound effects. In
order to receive the 6. channels, you will need a Dolby Digital
EX receiver and also 6.1 source material, such as a 6.1 encoded
DVD.
Dual Antenna
Inputs- Devices with dual inputs can accommodate
two antenna sources, such as external off air antenna and cable
or satellite decoder. This allows you to easily switch between
sources without the use of external switching devices.
DVD Changer-
This is a DVD player that is capable of playing multiple DVD's or
CD's. Changers come in a rotary platter that holds 5-6 discs or a
mega-changer, which can hold up to 400 discs within a single
machine.
DVD
Recordable- This is a device capable of recording
data onto a DVD disc. There are presently 3 schemes for
re-writable DVD which include DVD-RAM,DVD-RW and DVD+RW. There is
also a write once DVD recordable format, which allows a one time
write and then locks the disc so no more data can be added.
DVD-Audio- A
DVD-Audio disc has the capacity to store more than 7 times the
amount of information that that of a standard compact disc. This
translates into more then 4.7GB of data. The structure of a
DVD-Audio disc allows data to be mastered on both sides, allowing
12x the data storage potential then that of a standard CD.
DVD-Audio is un-compressed, allowing a much richer fidelity. Most
DVD-Audio discs contain Dolby Digital audio tracks so they can be
played on any standard DVD player.
Digital Video Interface
(DVI)- DVI was created as a standard tp provide a
high bandwidth, digital interface between a video source and a
display device. As part of the standard, a High Bandwidth Digital
Content Protection scheme (HDCP) was developed to create a secure
link between the source and display. It does not allow recording
of the digital signal. DVI delivers video in an un-compressed
format, allowing real time complex graphics displays and user
interfaces found in program guides and other interactive features
for HDTV.
DVI
Input/Output- An uncompressed connector used to
pass digital video signals from HDTV receivers to other source
devices such as DVD players.
DTVLink- See
IEEE 1394 for details.
External Speaker
Jacks- These allow you to connect external
speakers to your television for improved sound quality. This is
usually done when no external amplifier/audio receiver is
available. Power output is dependant on your television's
internal amplifier, which is usually minimal.
Firewire- See
IEEE 1394 for details.
Frequency
Response- The sampling rate, measured in
kilohertz is the number of time per second the audio wave form is
recorded for frequency and loudness. Standard CD players have a
frequency response of 44 100 times per second, while a DVD player
has a frequency response of 96 000 times per second.
Front Audio/Video
Jacks- This refers to a set of composite
audio/video jacks on the front of a television, which can be
handy for connecting camcorders or video games.
HDCP- High
Bandwidth Digital Content Protection (HDCP) is a copy protection
scheme developed by Intel which uses a special authentication
protocol to protect programs from being copied. When enabled, the
end user device, such as a HDTV receiver must first verify that
it is licensed and allowed to be received and if it is, a
hardware handshake is exchanged and the program is
transmitted.
HDMI Input-
This is a successor to DVI, which is able to pass audio and video
signals securely. The HDMI interface resembles a USB
connector.
iLink- See
IEEE 1394 for details.
Resolution-
Resolution refers to the number of lines that can be displayed on
a standard television. Theoretically the more lines of resolution
that can be displayed, the better the picture quality. The NTSC
broadcast television standard is 525 lines, of which 330 lines
are displayed on a standard television. VHS videotapes offer
approximately 240 lines, super VHS tapes offer up to 400 lines,
and DVDs offer approximately 500 lines of resolution.
IEEE 1394-
Also known as Firewire or DTVLink, this refers to a flexible
digital connection standard supporting daisy chaining and
branching for peer-to-peer implementations. IEEE 1394 can also be
defined as a network providing inter-operability between digital
audio and video applications, capable of transmitting
high-quality audio and video streams between devices.
Invar- An
invar shadow mask is a premium feature available on select
television models that is designed to give the picture more
brightness and a crisper appearance.
Liquid Crystal Display
(LCD)- LCD front and rear projection televisions
use LCD panels to create images, which are then enlarged to fill
the screen. An LCD projector produces rich, vibrant colors and
sharp contrast to produce a large, high quality picture.
Liquid Crystal on Silicon
(LCOS)-Liquid crystals are coated onto a silicon
chip, which uses a reflective, aluminized layer. This reflective
design increases contrast. Since it is a digital display device,
LCOS also eliminates image burn in.
MPEG-2- MPEG-2
is the current data compression system widely in use today. It
compresses data by locating and retarding redundant or repetitive
image signals, thereby freeing up bandwidth or disk space for
moving images.
Multi-Channel
Outputs- A set of analog audio outputs designed
to pass DVD audio from the DVD player to an audio receiver.
Notch Filter-A
notch filter helps to remove a small section of the video signal
that contains excess color information. This helps to eliminate
some unwanted color effects. The circuit however contributes to a
small degradation in picture resolution.
Picture in Picture
(PIP)- This feature which is available on
mid-high end televisions allows one to view video from two
sources simultaneously. A smaller picture of the secondary video
source appears on the screen and you are able to alternate
between the two.
Progressive
Scan- Progressive scan adds three dimensional and
flicker free picture quality. A progressive display produces an
entire frame of all visible lines of resolution, rather than the
interlaced format of displaying odd lines on one frame followed
by even lines on the next frame. Progressive scan devices also
process information at a higher rate, which allows for a high
color resolution.
Super Audio CD
(SACD)- A new aural scheme from Sony and Philips,
the original inventors of the compact disc that adds a much more
robust musical format than that of the standard CD. An SACD has a
sampling rate of 2 882 400Hz, 64 time higher than that of a
standard PCM CD at 44 100Hz. Additionally, the frequency response
has been broadened to 100Hz, allowing you to hear a much broader
detail of the music.
Surround
Sound- Many mid to high end televisions are now
including surround sound with their sets. Rear speakers are
required for full pro-logic mode. The downside to this is a
televisions amplifier is quite limited in power, usually 5 to 10
watts per channel, which is why many people that want a good home
theater setup opt to purchase a separate audio receiver to handle
this task.
S-Video Input-
S-Video provides 400 lines of resolution, which will improve your
picture clarity beyond that of regular RCA type composite Video
connections. S-Video uses a special 9 pin connector, which
consists of a Y channel and a C (chrominance) channel that
contains R-Y and B-Y signals. S-Video bypasses the comb filter,
but still passes through the NTSC decoder. For best possible
picture quality, see component video.
Video
Inputs/Outputs- This refers to the number of
inputs and outputs in a component. There are usually less video
outputs than there are audio. These allow you to connect external
media devices such as DVD players, camcorders, VCR's, PVR's and
more.
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