it’s a digital world ccta 2008

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It’s a Digital WorldCCTA 2008


Transitioning to an All Digital Network

As most Operators know, a number of FCC rulings are forcing all Cable Operators to look at a transition to an All-Digital Network.

– In 2009, Analog TV Stations across the U.S. and U.S. territories will shutting down in favor of new dedicated channel assignments broadcasting All-Digital programs using a modulation scheme called 8-VSB.

– All new Set Tops coming from Vendors, as well as QAM TVs are to have separable Conditional Access in the form of Cable Cards.

– Most new Set Top offerings from Vendors no longer have Analog Tuners, hastening the push towards an All-Digital Lineup.

This discussion focuses on the key Headend components that will need to be added to allow for an easy, cost effective move toward an All-Digital Lineup.


Cable: The Analog Days

– Over the years, the FCC and other Government agencies around the world have created frequency allocation maps which assign specific RF frequencies to all VHF and UHF channels. This map is non-negotiable and all broadcasters and manufacturers must follow it to ensure compatibility (and to avoid interference from channel to channel) on all equipment.

– At different points throughout the years, these agencies have also allocated frequency maps to cable operators. Because these maps were implemented throughout different periods and because lower frequencies carry better on coaxial cable, cable maps do not match the off-air map for all channels and the cable channel frequencies are not always in order.

– A channel is defined as 6 Mhz of space and it takes a full 6 Mhz to broadcast 1 analog video (AM modulation) with synchronized audio (FM modulation).

Example-Channel number Off-Air Freq Cable Freq

2 55.25 55.25

3 61.25 61.25

22 519.25 169.25

23 525.25 217.25


Analog combining


Digital Cable

In the mid to late 90s, Cable Operators around the world began to deploy a digital tier of cable. This was necessary to compete with satellite competition and to free up precious space.

Digital is defined as an on or an off…also known as a 0 or a 1.

A Stream of meaningful zeroes and ones can be sent to a destination computer (or in this case, a decoder/set-top) where the destination device is able to read the language of zeros and ones and do what is requested in the transmission.

The language used by Cable Operators is known as MPEG-II (or in some cases DVB, an MPEG-II based format with additional Tables in the stream), which allows analog video and audio to be digitized, sent as a Transport Stream, and decoded back into analog video and audio at the other end.

In the analog world, only one video can be sent in a 6 Mhz channel. But if the video is digitized and compressed with MPEG-II, 10 or more services can be sent using the same 6 Mhz channel using 256 QAM modulation.


MPEG Compression

MPEG offers superior video/audio quality at significant bandwidth savings. Digitizing a standard U.S. movie without means of compression will produce a transport stream of about 168 Mbps. Using 256 QAM modulation, it would take 5 separate 6 MHz channels to transmit one movie.

Using an MPEG-II transport stream, this bit rate can be reduced to a 3-4 Mbps elementary stream (a 50:1 reduction) without significantly effecting perceived video quality.

This allows an MSO to transmit this movie plus 9 or more movies in just one 256-QAM 6 MHz channel.


Set Top Basics A channel map will contain virtual channels (the channel displayed on the cable set top box) and

the real FCC defined channel. The frequency is fixed by the FCC, based on tuned channel.

Analog Set Top Channel Map

When multiple video services are combined into a single transport stream for transport on a 6 MHz channel, each service is assigned an MPEG (also called Program or Service) number.

Digital Set Top Channel Map

Cable box channel Service Tuned channel

2 FOX 2 (55.25 Mhz)

3 Sci-Fi Channel 3 (61.25 Mhz)

4 ABC 32 (271.26 Mhz)

5 CBS 5 (77.25 Mhz)

Cable box channel Service MPEG service # Tuned channel

2 FOX 1 2 (55.25 Mhz)

3 Sci-Fi Channel 2 2 (55.25 Mhz)

4 ABC 3 2 (55.25 Mhz)

5 CBS 4 2 (55.25 Mhz)


Digital modulation

Using a 6 Mhz channel for transmission, the data rate depends on modulation

Using 64 QAM, the maximum transmission rate is 27 Mbps.

Using 256 QAM, the maximum transmission rate is 38.8 Mbps.

IMPORTANT- If the accumulative data rate of all services exceed the total max allowed, all pictures break up!!!


Typical Program Data RatesA service can be encoded as a CBR or a VBR service.

CBR- Constant Bit Rate. The bit rate is constant regardless of scene complexity, resulting in either wasted bandwidth or a low quality service.

VBR- Variable Bit Rate. The bit rate constantly changes based on the complexity of each scene. Quality remains constant.

Typical bit rates- Locally Encoded Services- 3-6 Mbps CBR (depending on settings) Most satellite delivered services- Approx 3 - 4.5 Mbps average Sports programming- 4 - 6 Mbps average HDTV Services will vary greatly depending on the Broadcaster. For DTV services, the

bit rate is typically around 5 Mbps. HDTV rates are usually between 11 – 19 Mbps.

This means that a 256 QAM 6Mhz channel (38.8 Mbps) can comfortably carry about 9-10 services before risk of exceeding 38.8 Mbps.


Optimizing your Programming…

Statistical Remultiplexing involves the use of two important functions: Statistical Remultiplexing (also called Rate Shaping or Transrating) allows an Operator to choose only

the services he desires from multiple Transport Streams (TS) and create a new TS with the new services chosen.

Since most services are VBR (variable bit rate), the bit rate is always changing. However, the TS total Bit Rate cannot exceed 38.8 Mbps, so a Transrater must “manage” the Bit Rate of each service to avoid exceeding the TS bandwidth.

Additional Advantages of Advanced Next Generation Statistical Remultiplexers DPI (Digital Program Insertion). Most Transraters can perform Digital Ad Insertions into Output

Program Streams. Graphical Overlays and Logo Insertion. Some Next Generation devices are beginning to offer the

capability to inject Ad Content via Graphic Overlays on existing programming. Next-Gen Products which offer Graphical Overlays can usually offer Text Crawls, too. Most Next-Gen products can Transrate hundreds of services simultaneously.

Statistical RemultiplexerStatistical RemultiplexerSelected Selected ProgramsPrograms

Original Original TransportsTransports

New Transport New Transport StreamStream


Encoders vs. Statistical Remultiplexers

Going Digital begs the question of how to manage all existing services:

– All Off-Air HDTV Services are already Digital. However, they are not efficiently muxed for Cable System Transport. Most Off-air DTV Services can range from 5 Mbps to as high as 19 Mbps. However, the digital modulation used (8-VSB) restricts the maximum bandwidth to 19.39 Mbps. 256 QAM has a Transport Stream Bandwidth of 38.77Mbps. Decoding and re-encoding using encoders involves multiple devices and forces a high quality signal back to a semi-analog state. It is also costly. A Statistical Remultiplexer, also known as a Transrater can multiplex 3 or more HDTV services at 15-19 Mbps or combine 1-2 HD Services with multiple SD services easily as part of a 256 QAM destined Transport Stream without ever re-encoding.

– Most Satellite services will be digital directly from Satellite. The question becomes, should you decode and re-encode or send these through a Transrater as well. Most Transraters can reduce the aggregate bit rates of incoming services by up to 25% without ever causing serious degradation of quality. This means 12-13 services can comfortably be remultiplexed without issue. In rare circumstances where extreme bandwidth savings are required and an Operator needs to reduce bandwidth on a Transport Stream by more than 40%, decoding and re-encoding using a Real Time Encoder will always be the better choice.

– In some circumstances, certain services from satellite may still be analog, even after 2009. In this case, a Real Time Encoder will always be required.


How Transraters work…

Managing service bit Rates (transrating) is done through several methods:

Stripping out null padding from encoder generated Constant Bit Rate (CBR) streams. This method does not affect picture quality.

Time shifting. Because the transport streams are being buffered, recreating a mux allows the opportunity to manage the buffers to ensure no two services peak at the same moment in Bit Rate. This method does not affect picture quality.

Re-quantizing the video as required. This is usually achieved through proprietary algorithms. These methods above can often achieve a 25-40% reduction of Bit Rate without significant loss in quality, depending on the original content.

Transport StreamTransport Stream


Digital Program Insertion (DPI)

Since 1997, the Digital Video Subcommittee of the SCTE has been developing standards, now known as SCTE 30 and SCTE 35. The specification makes Digital Ad Insertion functionally equivalent to analog Ad Insertion

SCTE 30, Digital Program Insertion Splicing API:

This Application Program Interface (API) creates a standardized method for communication between Servers and Splicers for the insertion of content into any MPEG-2 Output Multiplex in the Splicer. This API is flexible enough to support one or more Servers attached to one or more Splicers. Digital Program Insertion includes content such as spot advertisements of various lengths, program substitution, public service announcements or program material created by splicing portions of the program from a Server:

-cue tone detection.

-which ad streams require insertion into which source stream.

-general status information.

SCTE 35, Digital Program Insertion Cueing Message for Cable:

This standard supports the splicing of MPEG-2 streams for the purpose of Digital Program Insertion, which includes advertisement insertion and insertion of other content types. An in-stream messaging mechanism is defined to signal splicing and insertion opportunities:

-Provides for a digital equivalent to analog cue tones.

-Encoders will insert the message packet in the MPEG transport stream (as an elementary stream) which will be detectable by the Headend splicing device.


Graphic and Video Overlays:Targeted and Addressable Applications

Adding overlays on multiple streams simultaneously creates new Ad Insertion possibilities

– Embedded in picture

– Not a separate video stream

Type of overlays

– Motion Text Crawls– example: EAS/promotions

– Graphic/Bugs – example: logos/branding

– Motion graphics – example: iTV/ads

This is a test of the Emergency Alert System

Want to buy PGA tickets? (Y / N) Want to buy PGA tickets? (Y / N)

See the latest shoe


Ad Campaign Communications

Digital Overlay Graphic Video and text can be stored on the

Transrater or externally.

Ad Campaign Server

DVS/629

One national video production customized for targeted advertising

Operator Messaging

Server


Getting ready for an All-Digital System

Recently, every major operator has begun a process of “Simulcasting” all analog lineup services as digital services as a first step towards All-Digital.

In essence, every analog service is MPEG encoded (if necessary) and stat-muxed together for transport to remote Headends.

These transport streams are typically transported as GigE MPEG video through switches and routers to remote Headends and Hubs.

At each site, the Transport Stream is fed into QAMs and mapped in place of existing analog services at the digital set-top.

The transport stream is also typically fed into decoders, BTSC encoders, SAP generators and NTSC modulators to supply the analog line-up for “cable ready TV” customers and lifeline customers.


Advantages of a simulcast environment

Simulcast Advantages in the Digital Line-up:

An all-digital lineup for customers (as opposed to existing digital tiers) with digital set-tops (and QAM TVs) eliminates the sole advantage of a satellite operator...a fully digital lineup.

Broadcasting services in digital will improve picture quality by providing the same picture at the Set-top which is found at the Headend. In essence, degradations like CNR, color distortions and ingress/egress are virtually eliminated as services are sent through a cable system.

One lower cost ad insertion system can be managed, instead of an analog, as well as a digital ad insertion system.

Additional Ad zones can more easily be added at a lower cost, increasing revenue.

Lineup changes no longer require rewiring existing Headends.


Digital Over Analog for the basic tier

Digital will always have an end of run advantage over analog. Low signal, low CNR, Cross-mod and other common artifacts will always be noticeable on an analog service. Provided the tiling threshold of a digital signal has not been crossed, the digital equivalent will still reproduce the same picture that is found at the Headend.

Digital Analog


Analog Advantages of Simulcast

Simulcast Advantages in the Analog Line-up:

Complete Headends can be collapsed into simple Hubs using decoders with RF outputs, making maintenance and repairs easier at each site.

A decoder/RF Upconverter product purchase would also allow easy replacement of old failing modulators at a reasonable cost.

Headend reliability goes up significantly with the reduction of racks of satellite receivers and single channel analog fiber transport systems (if applicable) plus the new found ability to purchase full Headend redundancy at an affordable price.

Better remote monitoring becomes available with the GUIs available from new decoders.

A single lower cost ad insertion system can be managed, instead of an analog, as well as a digital ad insertion system.

Additional Ad Zones can more easily be added at a lower cost, increasing revenue.

The reduction of so much older equipment can save 10s of thousands of dollars a year in Electricity and Cooling costs.


All-Digital Transition Diagram


VOD (Video on Demand)

With Video on Demand, one or more QAMs are dedicated to specific nodes or groups of people (often known as a service group).

The QAMs will not broadcast any video until requested to by the VOD Server. Once a request is received from a Set Top, the VOD will play a movie or other content from local hard drives

out to a specific QAM. As more users watch movies and other content simultaneously, additional QAMs can be added.

1. A Customer selects a movie through an Interactive VOD Guide

2. Software in the digital set top sends the request for the movie to the VOD Server at the Headend.

3. The VOD Server will stream the movie over a GigE Network to a destination QAM.

QAM

GigE Switch


A VOD QAM Environment


VOD Bandwidth…is there a solution?

In the world of Video On Demand, all streams are CBR and typically 3.75Mbps. HD VOD has a considerably higher data rate. This means that no more than 10 services can ever be joined per QAM.

– As VOD becomes more popular, some Cable Operators have reported double digit increases in VOD subscription rates month to month.

– As network usage increases, additional QAMs must be added to each zone.

– Every QAM added requires another 6 MHz of valuable bandwidth.

– Once channel capacity is reached, more costly and time consuming node splits must be implemented to free up QAM space for each customer.

– If an area has a sudden reduction in VOD buys due to special promotions, the money spent above can be wasted, making today’s architecture less scalable than desired.

Is there a better way???


Why not Rate Shape at the QAM???

Ideally, putting a Statistical Remultiplexer in front of the VOD QAMs would easily create more efficient QAMs packing as many as 14 services into the same QAM. However, there are several reasons why this has not been possible in the past.

Statistical RemultiplexerStatistical Remultiplexer

3.75Mbps 3.75Mbps VOD VOD

ProgramsProgramsMore efficient VBR More efficient VBR Transport StreamTransport Stream


Issues with Rate Shaping- COST

The cost per stream with today’s Transraters has been cost prohibitive for a VOD environment, where thousands of streams must be Transrated simultaneously.

The average per QAM cost for Rate Shaping is between $6,000 - $10,000 (U.S. Currency), depending on the Vendor chosen, special Operator pricing, volume of purchase, etc.

A typical VOD deployment in a medium to large sized city can involve more than 1000 QAMs.

This would mean an initial cost of up to $10 Million!!!


Issues with Rate Shaping- SPACE

Space would be a huge issue. With thousands of streams, today’s solutions would require racks of equipment in Headends where space is at a premium.

At 160 Mbps of output processing (4 QAMs) in a single RU, you would need to buy 250 Motorola CherryPicker DM-6400s, filling 14 7 Ft racks with DM-6400s!!!

At 640 Mbps of output processing (16 QAMs) in 12 RU, you would need to buy 63 BigBand BMRs, filling 21 7 Ft racks with DM-6400s!!!

Even with the extreme density of the RGB BNP, at 1280 Mbps of output processing (32 QAMs) in 1 RU, you would need to buy 32 RGB BNPs, filling 2 7 Ft racks with DM-6400s!!!


Issues with Rate Shaping- Video Delay

Statistical Remultiplexers induce delays of 1.5 – 2.1 seconds (depending on the Vendor) from input to output. This would not scale in a VOD environment where channel changes must feel near instantaneous (less than 1 second).

The Motorola DM-6400 has about a 2 second delay from input to output.

The BigBand BMR has about a 1.8 second delay from input to output.

The RGB BNP has about a 1.4 second delay from input to output.


– New products just coming to market can Transrate 1200 services simultaneously, which equates to 80 256QAM Transport Streams. Since less hardware is required, cost is decreased dramatically, solving the issue of cost. Per QAM costs can now be in the low hundreds instead of near $10,000.

– Since a single rack unit SDV/VOD Transrater can manage 80 256QAM Transport Streams, the space issue has also been solved.

– Special SDV/VOD Transraters can Transrate at delays of less than 400ms, which makes delay imperceptible to end users.

– More Vendors are expected to compete in this area moving forward, allowing for choice and competition.

New Products address this need…


BW Savings with VOD Transrating

Standard Definition Content

High Definition Content

Percentage of Video Rate reduction 0.00% 5.00% 10.00% 15.00% 20.00% 25.00% 30.00% 35.00% 40.00%

Average Bit Rate per Service3.75 3.58175 3.4135 3.24525 3.077 2.90875 2.7405 2.57225 2.404

Bandwidth required for origional CBR services 37.5 35.8175 34.135 32.4525 30.77 29.0875 27.405 25.7225 24.04Number of streams per channel 10 10 11 11 12 13 14 15 16Total number of 6 MHz Channels needed 100 100 91 91 83 77 71 67 63

Number of channels Saved/Freed with Transcoding

0 0 9 9 17 23 29 33 37

Percentage of Video Rate reduction0.00% 5.00% 10.00% 15.00% 20.00% 25.00% 30.00% 35.00% 40.00%

Average Bit Rate per Service15 14.26925 13.5385 12.80775 12.077 11.34625 10.6155 9.88475 9.154

Bandwidth required for origional CBR services 45 28.5385 27.077 25.6155 24.154 22.6925 21.231 19.7695 18.308

Number of streams per channel2 2 2 3 3 3 3 3 4

Note – savings shown in a system with 25 Service Groups (4 x 6MHz channels per group)


VOD Rate Shaping In Action


Company Background

– 3 Founders: Pioneers in digital TV/video

– Founders also founded Imedia– (CherryPicker)

– 100 employees, based in San Mateo, CA

– Offices in Europe, Asia and Latin America

Sound Financial Backing

– Strong Board of Directors

– Fully funded by top tier venture capital

– Raised $37M total

Products

– First product shipment in August 2005

– 50+ Cable and Telco customers

– Products have been sold in 10 countries US, Canada, Mexico, Chile, Columbia,

Bahamas, Honduras, Jamaica, El Salvador, Nicaragua, Guatemala, Trinidad

– 5-product family, 2000+ units shipped

Patented core technology

RGB Networks - Company Overview


Muchas Gracias!!!

it’s a digital world ccta 2008

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