Set-top
Boxes
This term (Set-top box) describes a specialised computer which
translates incoming digital signals into a form suitable for viewing on
a standard television set. The source of the signals could be a digital
satellite or terrestrial broadcast, a cable television channel or a
video-on-demand programme sent down a telephone line.
Set-top box, sometimes abbreviated to set-top or STB, is a somewhat
misleading term as the device is not necessarily placed on top of the
television set and is not necessarily a box.
Other projected uses for the set-top box include control of interactive
viewing, for example with a home-shopping channel or WebTV; it may also
decrypt signals on subscription or pay-per-view channels. The term is
an obvious compound, helped towards acceptance by its form and rhythm,
even though, as one commentator remarked, it is normally found under
the set rather than on top of it.
Set-top
Box - (STB) - May
be known as
set
top, Set-tops, set-top box, set top box, STB, Receivers, Converters,
Decoders, Intelligent Set-top Boxes, Set-top Decoders, Smart
Encoder, Digital TV
Converter, DTV Converter, Voice-enabled Set-top Boxes, Digital Decoder,
DTV Tuner, Descrambler, Digital Set-top Box, Addressable Converter,
Demodulator, Smart TV Set-top Box, ITV enabled Set-top Box,
Internet-enabled Set-top Box, ITV enabled Set-top Cable Box,
Satellite-enabled Set-top Box, Cable-enabled Set-top Box, Low-end
Boxes, Thin
Boxes, Thick Boxes, Smart TV Set-top Box, Super Box, All-in-one Set Top
Box, Integrated Set Top Box, Hybrid Cable
Box, Media Center. Associated
with Digital Media Adapters, Digital
Media Receivers, Windows Media Extender Set-top Boxes, Gaming Consoles.)
Its ancestor is often considered the
Nintendo game box as
those ancient 8-bit game boxes had data ports. (A data port is a
physical interface on a device through which information travels.) A
set-top box (STB) is a device that connects to an external signal
source and decodes that signal into content that can be presented on a
display unit such as a TV.
Modern day set-top boxes generally are
digital devices that communicate using computer language. In the past
when the set-top box
functions were built in to another device, such as a TV, it might have
been referred to as a device with a “built-in”. Now-a-days the phrase “built-in”
has been superceeded by the phrase "integrated". Now a TV with set-top
box functionality built into it is more often called an "Integrated TV". If it's a digital
TV, it would be known as an "Integrated
Digital TV" (iDTV). Do note that just because a TV has
set-top box
functions built in to it, that doesn't mean it's a digital TV. In
that case it's just an analog TV with set-top box functions
built into
it.
A
set-top box is a computerized device that
processes digital information. Set-top boxes (STB) come in many forms
and can have a variety of functions. Digital
Media Adapters, Digital
Media Receivers, Windows
Media Extender and most video game consoles are also
examples of set-top boxes. Currently the type of TV
set-top box most
widely used is one which receives encoded/compressed digital signals
from the signal
source (perhaps your cable or telco TV provider's headend)
and decodes/decompresses those signals, converting them into analog
signals that your analog
(SDTV) television can understand. The STB accepts commands from the
user
(often via the use
of remote devices such as a remote control)
and
transmits these
commands back to the network
operator through some sort of return path. Most
set-top boxes deployed today have return path capability for two-way
communication.
STBs
can make it possible to receive and display TV
signals,
connect to networks, play games via a game console, surf the
Internet, interact with Interactive Program
Guides
(IPGs), virtual
channels, electronic
storefronts, walled
gardens, send e-mail, and videoconference. Many STBs
are able to communicate in real time with devices such as camcorders,
DVD and CD players, portable
media devices and music keyboards. Some have huge
hard-drives and smart card slots to put your smart card into for
purchases and identification.
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Generally put, to
provide
interactive services, the set-top box might need some or all of the
below:
(1) A network
that offers the potential for interactivity.
(2)
The network interface - This connects the STB to a network which
makes it possible to communicate
with the servers.
(3) A tuner is
electronics that 'catch' the incoming signal.
(4) The decoder
- In order to save storage space, disk
bandwidth, and network bandwidth, programming is usually encoded
(compressed) before being sent over the network to the STB. Thus, the
end-user
(subscriber) needs a decoder to decode (uncompress among other things)
the incoming
stream's data before it can be viewable on the TV. This is part of what
a modem does.
The decoding process may be known as (or include) Demodulation
(Heavy
Lifting.) It could include Demultiplexing.
Also see Codec.
H.264 (MPEG-4) compression technology utilizes up to 40 percent less
network bandwidth than the MPEG-2 compression used in most systems to
date.
(5)
The buffer - Due to delay jitters in the
network, the
exact arrival time of a video stream often cannot be determined. In
order
to guarantee continuous and consistent playback for the viewer, the
video and/or data stream(s)
may be received one or even a few
seconds before it's
actually seen by the end-user. This way if there are
fluctuations in the transport
time of the
streams to that receiver (aka set-top box, decoder), the viewer won't
know the difference as their
buffer has a bit of time to spare.
(6)
Synchronization software/hardware -
Video and
audio streams must be synchronized with each other before viewing.
Other streams may be added including those related to enhancements
(such as metadata.)
(7) Middleware
(8) Platform
(9) Applications
(10) Any
additional software and/or hardware.
(11) A return
path (back
channel).
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Set-top
boxes may be associated with
these major categories. (The below was originally written in 2002 and
has some updates):
(1)
Broadcast TV Set-top Boxes - (a.k.a. Thin
Boxes) - A more primitive set-top box with no back channel
(return path.) These might come with interface ports, some
memory and some processing power.
(2)
Enhanced TV Set-top Boxes - (May be known as: Smart
TV Set-top Box, Thick Boxes) - These have a back channel
(return path), often
through a phone line. These may be capable of Video on Demand,
e-commerce, Internet browsing, e-mail communications, chat and more.
(3)
Advanced
Set-top Boxes - (a.k.a. Advanced
digital Set-top boxes, Smart TV Set-top Box, Thick Boxes, All-in-one
Set Top Box, Media Center)
- A fully integrated set-top box.
These have good processors, memory, middleware,
software applications and optional hard-drives. They're often
used with
high-speed (broadband) connections.
Features could include high-speed Internet access, Interactive TV,
digital video recording & gaming. Instead of this, a "sidecar"
(below)
might be used in tandem with the set top box and/or
TV. Advanced set-top boxes are more likely to be integrated with DVRs
and high-definition
TV. See Media
Centers.
(4)
Sidecar - (Please
note this 2007 update; as advanced set-top boxes now typically are
integrated units, the sidecar is not often used.) - This type of
set-top
box provides an
additional transport stream of data from the network operator to
compliment the main stream. With Charter
Communications’, the BMC-8000 (Broadband Media Center) is/was
a
sidecar box that works in tandem with the Motorola DCT-2000. A fully
integrated unit would not require a Sidecar.
(5) Hybrid Digital Cable Box – A
specialized and often more
expensive cable TV set-top box with high end functions. Motorola
Broadband’s DCP501 home theater system is an
example.
(6) Over-the-top Boxes
- Electronic device manufacturers are providing DVD players, video game
consoles and TVs with built-in wireless connectivity. These devices
piggy back on an existing wireless network and pull content from the
Internet and deliver it to the TV set. Typically these devices need no
additional wires, hardware or advanced knowledge in how to operate.
Content suited for TV can be delivered via the Internet. These OTT
applications include Facebook and YouTube. Also see Internet-connected TV.
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In the States, CableCARD
can offer an alternative for cable TV users. The physical CableCARD is
a PCMCIA type II PC card approximately the size of a thick credit card.
These allows cable consumers in the States to view and record digital
cable television channels on DVRs, PCs and TVs without the use of
decoding equipment such as a set top box. CableCARDs unlock the
channels and services that the cable customer has subscribed to. Some
CableCARD technologies can even be used with devices that have no
physical CableCARD slots.
In
the States, Motorola and Cisco's Scientific Atlanta supply most of the
boxes
cable operators provide to subscribers.
Codec
Encoder - An encoder is a program and/or device
used to change a signal, or
stream of data, into a code that a compatible computerized device can
work with. This code may be further manipulated for optimal
results. This encoded data typically needs a "decoder" at the receiving
end to change
it into a signal or data stream that a TV or other applicable device
can
understand. (Analog TVs don't understand digital signals unless
the signal is "decoded" by the set-top box for them.)
Decoder
Demultiplexer
Firmware
- Firmware is often used in set-top boxes.
Media Center
Multiplex
Online Demonstrations/examples of
Set-top Boxes:
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Related Terms
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