1. Building Blocs for Digital Terrestrial TV – DVB-T/T2
Focus on Regionalization
David Mouen
January 27, 2011, Kiev
Good afternoon.
My name is David Mouen.
Within Thomson Video Networks I’m in the marketing team, in charge of the Digital Terrestrial TV segment.
I’m very pleased to present you the functionnal blocks required to build Digital Terrestrial TV headends, with a focus on multiplex regionalization.
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2. Introduction - Thomson Video Network overview
Agenda
Introduction - Thomson Video Network overview
Digital Terrestrial TV: New Services and Benefits
Multiplex Generation, customization and transport
DTTV System Key components
Conclusion

3. Thomson Video Networks throughout the Media Chain
Live events
Studio
Post-production
CONTENT PRODUCTION
Playout center
Network operation
Local
programming
National
Digital TV Headend
CONTENT DISTRIBUTION
Terrestrial
broadcasting
CONTENT RECEPTION
CONTENT TRANSMISSION
Fixed reception
Mobile reception
Thomson Video Networks provides innovative video compression and content processing solutions at the digital headend, all along with a competitive set of professional services that enable network operators and broadcasters to deliver the best HD, SD, Web and Mobile TV experience.
I start by a short intreoduction of my compagny.
Within the media chain TVN is positioned in the content distribution segment, addressing DTTV, but also Satellite DTH, Cable, IPTV, Web TV, Contribution.
TVN provides innovative compression and content processing solutions to build digital headends, all along with complete and competitive set of processional services (headend design, product delivery and installation, commissioning, training).
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4. Thomson Video Networks at a glance
15 years of innovation and continuous service to deliver leading-edge compression and network systems to network operators and broadcasters worldwide
Worldwide leader in HD, SD, Mobile TV head-end systems
Significant global presence to ensure close customer proximity
~400 employees with R&D center (200 employees), manufacturing location and multiple sales and services offices
Trusted supplier to hundreds of customers around the world
Over 25,000 active HD, SD and Mobile TV channels deployed worldwide
Culture of sustained innovation and technology
PTS
Kenya
DTTV
Key DTTV Customers
We have been in this business for 15 years, from the very beginning of Digital Television, as a worldwide leader in headend systems.
Our headquarter, R&D and factory are located in France, and we have a global presence to insure proximity with our customers.
We have a large reference base in DTTV applications, covering all continents.
For many of our references we have designed national, regional and local headends, from a few to over 30 regions.
I’ll just focus on 2 of them, which started digital TV with us more than 10 years ago: BBC and Teracom in Sweden. These 2 DTTV network operator where the first in the world to launch DVB-T2, in 2008 for BBC and end 2009 for Teracom, using again our solutions.
They both offers high definition services country wide, with the goal to provide regional customization in the future.
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5. Market leading PRODUCT portfolio
Video Compression
ViBE video compression family
“Powered by Mustang” compression engine
The industry standard for encoding and delivering superior video quality in all formats across all networks, including Mobile TV
Content Processing
NetProcessor video processing platform
A flexible, modular MPEG content processing solutions for handling valuable content.
Enable to differentiate at the edge to maximize revenue
MPEG Video
Servers
Sapphire broadcast server
A unique ingest, playout and insertion MPEG server with advanced video and audio processing features
Network Management & QoS
XMS & VTS 500 family for full video compression systems management
Powerful scheduling tools and management of complete transport system with tight interface to major CAS
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6. Digital Terrestrial TV: New Services and Benefits
Better Picture / Audio Quality
Digital video quality
High quality audio (digital codecs, 2.0, 5.1)
Improved reception
Increase coverage
Content
Customization
Multi languages per video
Thematic channels
Regional channels
Regional switchover
Ad Insertion
Mix of TV, radio, data
14 SD (T), 6 HD (T2)
Sharing Tx costs
Multiple Services over each frequency
Saving Frequencies
Opportunity for other usage (mobile, telecommunications, radio, …)
High Definition
Interactive Services
Electronic Program Guide
Teletext, Subtiltles
News, Games, …
Offering Pay TV
Live, push VOD
Now a short recall of the new services and benefits provided by DTTV
in stead of a single channel per frequency the digital standard allow to share the same frequency by multiple TV channels but also radio and interactive data applications. 2 example: 14 SD services in a DVB-T multiplex, or 6 HD channels in a DVB-T2 multiplex.
High definition is an obvious benefit of the DTTV.
Digitalization provides also a high quality picture quality plus enhanced audio experience with multiple audio channels, stereo and 5.1 surround.
Electronic progra guide, DVB subtiltle, and multiple interactive application are also availble.
Content customization is an other cost effective benefits of DTTV, with thematic channels, live to live regional switchover and advertising substitution in regions.
Pay TV can easely be deployed (full pay TV channels, PPV, VOD).
Last benefits is the saving of frequencies, enhanced by the use of Single Frequency Networks (SFN).

7. Challenge to Face: How to Build, Customize and Distribute DTTV Multiplexes?
Multiplex: The bitstream delivered by the headend, modulated by the DVB-T/T2 transmitter, …), demodulated, descrambled, decoded by the STB or the TV. ?
Channel #1
Playout Center
Channel #2
Playout Center
6, 7 or 8 MHz
Transmitters
Channel #N
Playout Center
DTTV STB
DTTV TV
Now the challenge is how to implement these services, how to build, customize and distribute the digital terrestrial TV multiplexes, from the TV channel playout center to the DTTV transmitters. 7

8. Example of Multiplexes – DVB-T / DVB-T2
Statistical Multiplexing
Dynamic bitrate allocation among a pool of encoders sharing a frequency.
Up to +30% efficiency.
DVB-T2
40,210 Mb/s
6 HD MPEG-4
DVB-T2
40,210 Mb/s
23 SD MPEG-4
SD/HD Encoders
DVB-T
24,882 Mb/s
7 SD MPEG-2
DVB-T
24,882 Mb/s
14 SD MPEG-4
Stuffing
down to 100 Kbps
First an overview of what is a DVB multiplex.
A multiplex is a bitstream with a global constant bitrate delivered by the headend , the result of merging / multiplexing MPEG packets delivered by a range of sources: digital encoders working in statistical multiplexing in order to optimize the bandwidth, signaling generators, Conditional access servers, ...
Common tables allows the decoder to identify the structure of the multiplex and find the components composing a given service, plus some common streams (EPG, conditionnal accesss data, …).
For each service 1 video component, 1 or multiple audio components, data components (teletext, DVB subtitle, digital cue tones for regional switch.
Stuffing packets are added in order to deliver an accurate CBR stream to the transmitter.
The first example is a DVB-T multiplex (typical bitrate 24,8 Mbps) shared by 7 MPEG-2 SD services, each with 3.2 Mbps video component and AAC stereo audio which gives an excellent picture and audio quality.
On the second example MPEG-2 is replaced by MPEG-4 and for the same video quality the number of channels is multiply by 2, 14 services, with 1.7 Mbps per video component.
On the next example the standard is now DVB-T2, with a typical available bitrate of 40.2 Mbps, which leads to 23 SD services.
The last one shows 6 MPEG-4 HD services sharing the 40.2 Mbps of the T2 mux.
Of course TV channels, radio, data, SD, HD, MPEG-2, MPEG-4 can be mixed in the same statistical multiplex and share the same frequency.

9. Digital Terrestrial DVB-T/T2 System Overview
Regional Head-end
Multiplex Customization
Telecom
Transmitters
Multiplex
Broadcasting
Regional Head-end
Multiplex Customization
Telecom
Transmitters
Multiplex
Broadcasting
Regional Head-end
Multiplex Customization
Telecom
Transmitters
Multiplex
Broadcasting
Regional Head-end
Multiplex Customization
Telecom
Transmitters
Multiplex
Broadcasting
National Head-end
Multiplex Generation
Broadcasters
Playout Centers
24/7 local insertion
The digital terrestrial TV system is spitted into the following parts
The national headend where the multiplexes are generated from content received from the Broadcasters.
The regional and local headend, where 3 type of customization are performed with local content:
24/7 local insertion.
Live to live national to regional, regional to national switchover, for example substitution of national news by regional news.
Advertising substitution (also called ad insertion)
Live to live National / Regional switch
Advertising substitution (Ad Insert) 9

10. National Headend - Architecture
Reception
Encoding
Multiplexing
Distribution
GPS
SDI
Router
QOS
Monitoring
RD1002 IRD
ViBE
HD Encoder
IP or ASI Router
QOS
From Playout Centers
Descrambler
NetProcessor
Multiplexer
DVB-S2
Modulation
ViBE
SD Encoder
NetProcessor
Network Adaptor
Service Multiplexing
Scrambling
SFN adaptation
DVB-T2 adapt
Data Insertion
To regions or transmitters
Telecom
Backbone
IP Router
Amethyst
Samless Switch
Sapphire
MPEG Video Servers
Conditional Access
servers
NetProcessor
Network Adaptor
XMS
Management
DataCasting:
EPG generator
IP, PDH, SDH
µW, Fiber
IP Encaps
Content is received from the playout over fiber, satellite or telecom networks, using appropriate devices, to feed the encoders with base band signals.
In the headend the very first job to perform is to reduce the bandwidth using MPEG compression for video and miscellaneous codecs for audio (MP1L2, AAC, Dolby 2.0, AC3, …).
This is the job of the MPEG encoders working in statistical multiplexing the video bitrate is reduced to an average of 3.2 Mbps for MPEG-2 SD, 1.7 Mbps for MPEG-4 SD, 6 Mbps for MPEG-4 HD.
The bitrate for audio encoding with a good quality ranges from 96Kbps for a stereo to a few hundred Kbps for Dolby encoding of 5.1 audio.
The encoder performs also VBI encoding (teletext, VITC, AFD, WSS). It can transcoder teletext directly into DVB subtitle.
Additional process like logo insertion can also be performed by the encoder.
In addition of the encoders MPEG server can be used for time delay or disaster recovery playout. Electronic program guides and servers for conditional access are also sources for the multiplex.
All these feeds are gathered by the multiplexer which performs scrambling for pay TV services, SFN or DVB-T2 adaptation, and multiplexing by delivering a single bit stream.
The multiplexes are then distributed to the regional headend and the transmitters over satellite using DVB-S/S2 modulation or over telecommunication networks (IP, µwaves, fiber, PDH, SDH).
The management function performs device provisioning and configuration, monitoring and redundancy in case of maintenance or failure of any component.
Quality of service is monitored via dedicated probes, reported to the management software.
The headend architecture is moving from ASI and base band signals to full IP.
ITV Carousel 10
Management

11. regionalization: 24/7 local insertion
Regional Headend
ViBE
Encoders
NetProcessor
Multiplexer
GPS in
National head-end
Encoder: MPEG-4 encoding of local channels (Statmux if more than 2)
Multiplexer:
Remultiplexing
Scrambling
SFN or DVB-T2 adaptation
IP or ASI delivery
Encoder: Encoding of national channels (Statistical multiplexing)
In the regional headend the first potential customization is the permanent insertion of local channels.
This is a quite simple task which requires encoders for the local channels and a multiplexer to combine the streams delivered by the encoders to the multiplex comming from the national headend.
Given that the multiplex is modified the SFN adaptation for DVB-T or the DVB-T2 adaptation has to be built or rebuilt.
There is no constrain on scrambling, all the services can be clear or scrambled before remultiplexing.
The generated multiplexe is then distributed to the transmitters.

12. regionalization: live to live Nat. / Region. switcH
Regional Headend
start
end BW I I
S1 National
S1 Regional
S1 National S2 S2 S2 S3 S3 S3
National Headend
SCTE35
ViBE Encoder
Broadcaster S4 S4 S4
Time
SDI
GPS in
ViBE Encoder
NetProcessor Multiplexer
Switch triggers
SCTE104 over SDI
SCTE104 over IP
Analog cue tones
GPI
Encoder - on trigger:
Digital cue tones insertion (SCTE35 tables)
I frame generation I
Multiplexer - On digital cue tones detection:
seamless splice from the national to the regional service and reverse (a few s latency) - Gop accurate OR
Service subsitution (50 ms, not seamless)
Service must be in clear
With even-id capability to select regions
Encoder
For quality optimization the service to substitute is VBR except during the switch.
Frame accurate solution thanks to I frame generation on splice points + SCTE35 commands.
An other type of regionalization is seamless live to live switchover, in the compressed domain. The typical application is to deliver regional news on a national channel.
The concept is to insert digital cue tones in the multiplex in the national headend, and based on these cue tones trigger the seamless switches in regions, according to the following workflow:
In the national headend the digital cue tones are inserted by the encoder. These are dedicated MPEG table attached to the service, called SCTE35 commands. They specify the switching time – or splicing time, with or without pre-roll. In addition of SCTE35 command insertion the encoder generate an MPEG I frame exactly at the splicing time in order to facilitate the job of the splicer.
The SCTE35 command insertion is triggered by SCTE104 commands, over IP, or inside the SDI input, or based on GPI or analog cue tone.
In the regional headend an encoder encode the local service and feed the multiplexer – also called splicer in this application.
On the detection of SCTE35 commands the multiplexer performs a seamless switch – or seamless splice – from national to local, and the reverse at the end of the substitution window. That process is GOP accurate, but thanks to the I frame generated on the start and end of the substitution window that process is globally frame accurate.
For MPEG-4 services for quality optimization the service to substitute can be VBR out of the window and go CBR during the splice period. For MPEG-2 service this constraint doesn’t exist and bitrate adaptation or bitrate shaping is used on all services to fit in the multiplex target bitrate..
In order to perform seamless splice in the compress domain the content must be in clear, so descrambled in case of protection of the satellite transport.
Given that the multiplex is modified the SFN adaptation for DVB-T or the DVB-T2 adaptation has to be built or rebuilt.
The generated multiplex is then distributed to the transmitters over satellite or telecom networks.
Multiplexer – complementary process
Scrambling, SFN or DVB-T2 adaptation

13. regionalization: Advertising substitution (Ad Ins)
Splice / Ad Server - On digital cue tones detection:
Frame accurate seamess splice, replacing live content by ad clips
MPEG-2/4 SD/HD CBR
Services must be in clear
Regional Headend
National Headend
Broadcaster
GPS in
SDI
ViBE Encoder
NetProcessor Multiplexer
Sapphire
Splicer / Ad Server
Switch triggers
SCTE104 over SDI
SCTE104 over IP
Analog cue tones
GPI
Encoder - on trigger:
Digital cue tones insertion (SCTE35 tables)
I frame generation
Multiplexer – complementary process
Scrambling
SFN or DVB-T2 adaptation
IP or ASI delivery I
The last type of regionalization is advertising substitution, in the compressed domain.
The concept is to insert digital cue tones in the multiplex in the national headend, and based on these cue tones trigger the seamless replacement of national advertising by regional ones, according to the following workflow:
In the national headend the digital cue tones are inserted by the encoder. These are dedicated MPEG table attached to the service, called SCTE35 commands. They specify the switching time – or splicing time, with or without pre-roll. In addition of SCTE35 command insertion the encoder can generate an MPEG I frame exactly at the splicing time in order to facilitate the job of the splicer.
The SCTE35 command insertion is triggered by SCTE104 commands, over IP, or inside the SDI input, or based on GPI or analog cue tone.
2 main components in the regional headend: the ad server / splicer and the multiplexer. Note: this simplified workflow don’t show the ad clip ingest and distribution to the ad servers.
On the detection of SCTE35 commands the ad server / splicer performs a seamless substitution of the national ad by a clip stored as transport stream file. The clip is identified by the SCTE35 command and a play list stored in the server.
In order to perform seamless splice in the compress domain the content must be in clear, so descrambled in case of protection of the satellite transport.
Given that the multiplex is modified the SFN adaptation for DVB-T or the DVB-T2 adaptation has to be built or rebuilt.
The generated multiplex is then distributed to the transmitters over satellite or telecom network.

14. Secure and efficient transport of SFN multiplexes
RD Demo+ Descrambler
Demodulation, descrambling of protected free to air services.
Agg +
DVB-S2 mod
DVB-S2 multi TS modulation
2 or 3 DVB-T multiplex in 1 transponder
Head-end
Telecom Network
NetProcessor
Telecom Network Adaptor
Provide transparent bit accurate transport over backbone.
Amethyst - Smart switch
Delay compensation.
Deep analysys
Seamless switch of MFN & SFN multiplexes
The multiplexes must be carried in an efficient and secure way from the headends to the transmitters. The transport must be transparent and bit accurate. This is particularly required for SFN networks for which all the transmitter of a give SFN area must absolutely receive the same bit stream.
Telecom transport
Network adaptors are used in the headend to convert the MPEG TS composing the multiplex to telecom formats (IP, PDH, SDH, ATM). Typically multiple ASI inputs to one IP output, one IP stream per multiplex. Forward Error Correction (FEC) overhead is added in order to correct transmission errors.
On the other side of the network the network adaptor cleanup the jitter and recover packet loss then deliver the multiplexes to the transmitters.
Satellite transport
Satellite transport is costly but in some countries it’s more affordable that building fiber or µwave networks to reach each transmitter.
With DVB-S2 and new modulation schemes like 8PSK or 16APSK a single transponder can carry multiple transport streams. Multiplexes can be transparently share the transponder bandwidth using the DVB-S2 multi stream feature of DVB-S2. On the receiving site the demodulator select the right multiplex using the ISI parameter.
Some content are free to air for DTTV but must be protected on the satellite transport. They have to be scrambled, using BISS fixed key or preferably strong DVB SC with dynamic keys algorithms similar to what is used for Pay TV. On the transmitter the demodulator performs descrambling.
Network Protection: Hitless Switch
For critical transmitters a main and a backup network can be provided, for e.g. main is satellite and backup is telecom. On the transmitter site an intelligent device analyze both streams and select the best one. That device performs delay compensation and provides a seamless switch form one path to the other.
Transmitter site

15. Key components for DVB-T/T2 headend systems
NetProcesor
ViBE
MPEG Encoder
Must performs superior video encoding at very low bitrate (SD/HD MPEG-2/4)
Audio codecs: AAC, Dolby 2.0, 5.1, …
Logo in, teletext processing, …
SCTE 104 and SCTE-35 compliant (digital cue tone insertion)
Multiplexer / Splicer
Multiplexer / remultiplexer, PSI/SI processor
Seamless splicing (SD/HD, MPEG-2/4)
Transrating
Scrambling
SFN adaptation, DVB-T2 adaptation
Sapphire
Management SW
Device configuration and monitoring. Handle service resiliency (redundancy)
Control the national and regional headends, monitor the transmitters
Control the QOS with dedicated probes.
Scale from small to very large systems .
XMS
Ad server / Splicer
Ad Insertion (SCTE-35/30 compliant)
GOP / frame accurate seamless splicing
Frame-accurate ingest of advertising clips (MPEG-2, H.264, SD, HD)
The key components of the distributed headends are:
The MPEG encoders which optimize the bandwidth for video and audio and insert digital cue tones in the compressed stream.
The multiplexer splicer for aggregation, signaling processing , seamless splice for regional switchover and complementary processing like scrambling, SFN and DVB-T2 adaptation.
The Ad server / splicer which performs frame accurate replacement of advertising triggered by SCTE53 commands and store the clips.
The management software, for device provisioning, configuration and monitoring, control of the quality of service via dedicate probes and handle the device redundancy.

16. Conclusion The best picture quality at low bitrate is a must
BW on DTTV network is very expensive, every Kbps must be used with efficiency.
Regionalization is key for DTTV competition versus DTH, IPTV, Cable - building blocs exist and provides Flexibility, efficiency & cost effectiveness
Local encoding, live to live switch, ad insertion, SCTE35/30 compliant.
Optimized & secure transport of multiplexes over satellite (DVB-S2 multi TS)
Future proof system design & integration required to face new features to offer, increase of regions and other evolutions
Scalable solutions required (features / sizing)
Flexible management SW, from contribution links to Transmitters
SFN & T2 adaptation, VBR, Ad Insertion, integrated Teletext to DVB sub, …

17. THANK YOU
4/20/2017