6. DVB-SNG:
standard for
news gathering
Multiprotocol
Encapsulation, or
MPE for short, is a
Data link layer
protocol defined
by DVB which has
been published as
part of ETSI EN
301 192.
It provides means
to carry packet
oriented protocols
(like for instance
IP) on top
of MPEG transport
stream (TS).
7. STANDARDS FOR BROADCASTING
Country: USA India Japan Brazil,Phillipines China
Integrated Services Digital Broadcasting (ISDB)
SCM(single carrier modulation), MCM(multicarrier modulation) (MCM
example: OFDM)
10. TERMINOLOGY
Multimedia Home Platform, or MHP in short
MHEG (the Multimedia and Hypermedia
Information Coding Experts Group) running over
DVB-T in the UK
11. @ MHP
The Multimedia Home Platform has been provided
in DVB as supplementary service for MHP-enabled
receivers
Two versions which are MHP 1.1. and MHP 1.2.
MHP used for transmitting HTML (Hypertext
Multimedia Language) files familiar from the
Internet, and Java applications.
Continued…
12. @ MHP
Starting the HTML and Java applications requires
special software (or middleware) in the receiver.
MHP-capable receivers are more expensive and
not available in great numbers on the market.
MHP applications are broadcast in many countries
but are currently really successful only in Italy
14. DVB STANDARD SCHEME
Encoding Stage Transport Stage Transmission Stage
For Encoding and Transport stage, both stages use
MPEG-2
15. MMDS
MMDS stands for Multichannel Multipoint Distribution Service. It is
used as replacement of cable TV service provider. MMDS is used to
cover rural areas where it is not possible to reach by broadcast
and cable TV operators.
16. LMDS
LMDS stands for Local Multipoint distribution service. It is used for
providing TV and 2-way internet service similar to MMDS.
NOC: Network
Operation Centre
26. INTRODUCTION TO VIDEO ENCODING
STANDARDS
Motion Picture Experts Group (MPEG) was
established in January 1988 as a work group to
create international standards of audio and video
encoders/decoders (codec)
MPEG-1 standard was published in 1989 and
approved as the international standard in 1992
MPEG-2 approved in 1994
New improvements, which would have lead to the
MPEG-3 standard, were later incorporated in the
MPEG-2. This caused the acronym MPEG-3 not to
be used
27. INTRODUCTION….. CONTINUED..
Structure of the MPEG-4 standard was set out in 1993
and the standard was approved in 1998
Work on MPEG-7, which covered audio and video
content, began in 1997 and the standard was approved
in 2002
The group is developing the MPEG-21 standard, which is
called the multimedia framework
This group is also working with other standards related to
the use of audio and video standards mentioned, such as
the Intellectual Property Management Protection
(IPMP)
MPEG is a member of the International Standards
Organization (ISO)
28. 1. MPEG 1 STANDARD
Aims at the compression of audio and video images
previously digitized
USES : Short video clips made available on the
Internet, video compact disks (VCDs), and videos
distributed on disks of the CD-ROM type use this
standard
MP3 audio compression is layer 3 of the MPEG-1,
thus the acronym MP3
Compression rate is variable and it’s possible to
reach a compression rate of 200:1
29. MPEG1 CONTINUED..
With the maximum rate the images become
distorted, because the compression introduces
artifacts in the image
It depends on the quality of the compression
algorithm and the compression rate used.
Thus, most of the videos compressed with the
MPEG-1 use a compression rate lower than 50:1
Even at this rate, the horizontal resolution obtained
after the compression is low, circa 320 lines, and
similar to the VHS format.
The compression used is the multi frame type
30. MPEG-2 STANDARD
MPEG-2 was developed in conjunction with the Video
Coding Experts group from the International
Telecommunications Union (ITU-T)
Also known in the ITU-T community as H.262
USES :DVDs and digital TV broadcasting use this standard,
which is more advanced than MPEG-1
Produces better quality images
The compression rate, just like in the MPEG-1, is variable
but normally values of around 40:1 are used
31. MPEG-2 ..CONTINUED..
More efficient at compressing, without apparent quality loss,
than MPEG-1
Demands higher computational effort in the process,
requiring more powerful hardware than that needed for
MPEG-1
The horizontal resolution obtained after the compression is
superior to that of the VHS format
Compression used is the multi frame type
Assembling process of the group of pictures (GOP) used by
the multi frame technique, it is more complex to compress
MPEG-2 content than to retrieve it
32. 3. MPEG-4 STANDARD
Standard created by the MPEG group for the
compression of audio and video images previously
digitized
Used on videos transmitted by the Internet, as well
as on cell phones that use images
Common on several standards of digital TV
broadcasting, especially HDTV in its advanced
video coding (AVC) version
MPEG-4 accepts different profiles
HDTV broadcasting systems use it as the encoding
standard, as an alternative to MPEG-2
36. INTRODUCTION
ATSC stands for the Advanced Television Systems Committee,
which developed the standards for DTV used in the United
States (as well as in Canada, Mexico, and Korea)
The principal standards comprise ATSC documents A/53 for
digital television and A/52 for AC-3 audio compression
ATSC DTV signals are not compatible with NTSC
One fundamental difference between digital ATSC and analog
NTSC television is that NTSC transmits complete pictures,
but the ATSC system effectively sends the pictures
broken down into many small parts, with a set of
instructions to put them back together again
So, what is produced and seen in the studio may or may not
be exactly what all receivers produce, depending on how they
interpret the instructions
This is the base for video compression
38. 8-VSB MODULATION
Type of Digital Modulation
8-VSB is a special form of AM modulation using a
single carrier modulated to eight different amplitude
levels
The carrier is modulated with a compressed
bitstream signal carrying all the information needed
for the channel
This modulation occurs at the transmitter in a piece
of equipment called an exciter
40. The compressed bitstream input to the DTV exciter
is processed and converted into digital symbols
The output of the exciter is a series of pulses of
carrier wave, each with one of eight different
amplitude levels that are assigned to eight symbols
These symbols are output at a rate of 10.76 million
every second.
41. TRANSMITTED BIT RATE
Each symbol is able to carry 3 bits of digital data
Therefore, the 10.76 million symbol per second output of
a DTV exciter can represent 10.76 * 3 = 32.28 Mbps
(megabits per second) of digital data
It is important to understand that the “data” being
transmitted may represent video, audio, or other types
of ancillary data information
Once in the bitstream, it is all referred to as data
Information bit rate for an ATSC bitstream is 19.39 Mbps
but data rate coming out of a DTV exciter so much higher
than the actual data rate of the video, audio, and ancillary
information being broadcasted
This is because of additional bits needed for forward
error correction ( FEC )
42. FEC-FORWARD ERROR CORRECTION
Forward error correction (FEC) is used to make the signal more
robust and able to withstand distortions in the transmission path
Multipath distortion is a common problem with over-the-air
television signals, caused when multiple signals from the same
transmitter arrive at the receiver at slightly different times
There may also be various forms of interference such as lightning
strikes that create large RF noise pulses, which can affect
reception at great distances from the strike.
Smaller RF pulses are created by electric motors, car ignition
systems, and many other things. All of these conditions can cause
data to be lost.
The special error correction codes added to the DTV signal helps
receivers to fix problems with the received signal.
In addition, DTV receivers have special circuitry called
adaptive equalizers to help cancel out the effects of unwanted
signals
43. CLIFF EFFECT
With analog television, the received picture can be excellent
(in areas of strong signal reception), mediocre, exhibiting
“ghosting” and “snow” (in areas of marginal reception), or
unwatchable (in areas of poor reception)
ATSC DTV pictures never display ghosts because, so long as
the receiver can decode the digital data that describes the
picture, it can reconstruct a nearly perfect picture
However, under extreme conditions, with low received signal
strength and/or strong multipath interference echoes, the DTV
receiver may no longer be able to correctly decode the picture
(and/or the sound)
In that case, the picture and/or sound disappear completely.
They go from perfect to nothing, with almost no intermediate
stage. This is known as the “cliff effect,” which is common to
many digital transmission technologies
45. DESCRIPTION OF ATSC BITSTREAM
The ATSC compressed bitstream, comprising digital
video, digital audio, and ancillary data, is known as
a transport stream
This is created by the ATSC encoders and
multiplexer and delivered to the television station’s
transmitter at a rate of 19.39 Mbps
The transport stream is made up of blocks of
compressed digital data, known as packets, which
carry video, audio, and ancillary data
This is in contrast to the continuous stream of
analog information for an NTSC signal
46. The ATSC packets contain 188 bytes of data, but the first
byte of each packet is used for synchronization, and an
additional three packets are used for management of the
bitstream, so 184 bytes are actually available for audio,
video, data, and PSIP (Program and System Information
Protocol Standard)
For comparison with the 19.39 Mbps data rate of the
ATSC bitstream, the fastest broadband cable Internet
connection available for the home can download data at
about 5Mbps, whereas a dial-up 56kbps modem for a
personal computer has a data rate of only 0.056Mbps
48. OTHER COMPRESSION SYSTEMS
Although AC-3 (Audio Coding-3) is widely used for DTV, it
is by no means the only compression system for audio
encoding.
Several other systems are widely used in radio and
elsewhere. These include an earlier Dolby system called
AC-2, also MPEG-1 layer 1, MPEG-1/2 layer 3 (usually
known as MP3), and the more recent MPEG AAC
(Advanced Audio Coding).
The recent systems provide much higher audio quality at
lower bit rates. There are continuing developments, and
a technique called Spectral Band Replication (SBR)
further improves high-frequency audio response in low-
bit-rate applications
49. ADVANCED COMPRESSION SYSTEMS
Recent developments in compression technology allow high
quality encoding with much greater efficiency than MPEG-2
The AVC/H.264 system (developed in conjunction with MPEG)
and the VC-1 system (based on Microsoft Windows Media 9)
provide equivalent picture quality at about half the bit rate or
less.
Such systems allow more programs to be transmitted in
less bandwidth.
However, because of the necessity not to make existing DTV
receivers obsolete overnight, broadcasters must continue to
use the MPEG-2 standard for many years to come.
Various proposals are under consideration to allow the new,
more efficient codecs to be used in some circumstances