Introduction to SDV

Owen Lin

April 18, 2007Some information obtained from:

Scientific Atlanta – SDV Overview

BigBand Whitepapers –The Statistics of SWB

What Is SDV and What Does It Do?

• Switched Digital Video– A technology which brings multicast efficiency to digital video

distribution– Enables MSO's (Multi Service Operators) to offer a wider

variety of programming– Efficiently manages their HFC (Hybrid Fiber/Coax) network's

bandwidth.

• Allocates bandwidth to requested channels • Frees up bandwidth from services no longer in use

– Traditionally, a broadcasted channel has permanent bandwidth allocated to it

• Wasteful if nobody is watching the service.• Detailed logs of bandwidth allocation and channel viewership

Why All the Rage?

• Competitive advantage, bringing the best for the least• Reduces investment cost - scales logarithmically to programming

services, rather than linearly

• SD (Standard Definition) channel uses about 3-6Mbps• HD (High Definition) channel requires approximately 15-22Mbps,

depending on the amount of motion and frequency of scene changes.

• A 256-QAM can supply 38.8Mbps. – That translates roughly to 9 SD channels or 1, maybe 2, HD

channels.

Example of Numbers

• An MSO broadcasts a 300 channel lineup, 20 of them HD's– 280 sd * 4 Mbps % 38.8 Mbps = 29 Qams needed per node *– 20 hd * 18 Mbps % 38.8 Mbps = 10 QAMs needed per node *– 39 QAMs are required per node (200-2000 tuners, varies by MSO)

• % = modulus

• An MSO uses SDV to offer a 300 channel lineup, 20 of them HD’s– The 80/20 rule followed by tv watchers – 56 sd, 4 hd channels are being watched by 80% of the audience

• 8 QAMs required– Covering vast majority of audience, approx 100 unique streams– about 1/3 the channel bandwidth

• MSO investment in QAMs at the hub level are heavily reduced

Additional Research

• BigBand, top 5 MSO, and S-A STB test trial on SDV– 915 subscribers– 171 switched channels– 100 streams resourced (only 67 were required in hindsight)

Kagan Research

• A study conducted by Kagan Research found that at any given moment the actual number of broadcast channels being viewed within a given node was far less than the number being broadcast.

Why Switched Digital Video?Bandwidth

• SDV– Gives your site more

flexibility to deliver more of the services that consumers want today

– Allows greater bandwidth capacity because NOT every channel is delivered at the time

Switched Digital Video

Switched Channels Everyone could get

their own special channels: increased

appeal of overall package to ALL

subscribers

Broadcast Channels

Au

die

nc

e

Broadcast Channels

Current Analog & Digital Broadcast Approach Only the most

popular channels are offered due

to capacity constraintsUnused

Capacity

“The Long Tail”

Why Switched Digital Video?Summary

Traditional Broadcast Switched Digital Video

200

ProgramsOffered

20QAMs

HFCBandwidthRequired

300

ProgramsOffered

30QAMs

HFCBandwidthRequired

200

ProgramsOffered

6-8QAMs

HFCBandwidthRequired

300+

ProgramsOffered

nQAMs

HFCBandwidthRequired

Bandwidth scales as number of

offered channels Immediate bandwidth

savings

HFC bandwidth scales based on viewership

HFC bandwidth required is

independent of number of

offered channels

MSOs can save bandwidth by delivering programs based on viewership

Section:SDV

Elements

DNCS

SDV Manager

SDV Server

Mini Carousel

DCM

NetCrypt

Switches & Routers

QAMs

STB Client

Management

SDV ElementsManagement Network – Key Players

HFCNetwork

VideoContent

IP Network

ControlIP Network

QPSK

ContentSources

DNCS

DCM

SDV Server

GQAM

SDV Client(on STB)

NetCrypt

Management& Provisioning

Server Interactive Session Request

MiniCarousel

Channel Change

Message

SessionBinding

ShellSessionSetup

IGMP Join

Out-of-BandChannel

Video Sources

GroomedVideo

EncryptedMulticast

Video

In-BandChannel

SDV ElementsDNCS

• DNCS System Release (min 4.2.0.2xx)– Features enabled with separate licenses

• Session Resource Manager (SRM)– Governs access to content and network resources– Allows sharing of those resources by various applications

• SDV Manager– The user interface for control of the SDV servers and system– Provides a means for operator configuration of the service group

assignments and various settings for the SDV servers.

• NetCrypt™ Bulk Encryptor enabled• SDV enabled

DNCS

SDV Elements SDV Server

• The SDV server is part session manager in that it communicates directly with settops requesting channel changes

• It is also part resource manager — it requests that shell sessions be set up on a QAM feeding the required service group

• Reallocates unused bandwidth• Generates the Mini Carousel• The SDV also monitors

– Bandwidth– Channel Changes

SDV Server

SDV Elements Mini Carousel

• Mini Carousel– Carries information about the programs that are currently

being carried in the SDV service• Includes IP addresses of primary and back up servers

– Operates between the SDV Server and the SDV Client– Provides a method of

distributing tuning information to enhance channel change operation

Content Delivery

SDV ElementsContent Delivery Network – Key Players

HFCNetwork

VideoContent

IP Network

ControlIP Network

QPSK

ContentSources

DNCS

DCM

SDV Server

GQAM

SDV Client(on STB)

NetCrypt

Management& Provisioning

Server Interactive Session Request

MiniCarousel

Channel Change

Message

SessionBinding

ShellSessionSetup

IGMP Join

Out-of-BandChannel

Video Sources

GroomedVideo

EncryptedMulticast

Video

In-BandChannel

SDV Elements DCM / Staging Processor

• The Scientific-Atlanta staging processor is the Digital Content Manager (DCM)– Grooms and conditions signal sources– Aggregates multiple MPEG sources– Converts MPTS to SPTS– Encapsulates MPEG into IP/GbE– Outputs unicast IP or multicast IP as needed– Clamps content streams

to specified bandwidth

DCM / Staging Processor

SDV Elements NetCrypt™ Bulk Encryptor

• The Bulk Encryptor receives the IP content streams from the DCM / Staging Processor– SDV streams are treated as broadcast streams for purposes of

encryption • Generates and sources the IP multicasts for encrypted switched

streams • Also used to generate multicasts for unencrypted streams.

Bulk Encryptor

SDV Elements Switches & Routers

• All connections are passed through router(s) which support IGMP v3

Switches & Routers

SDV Elements QAM Modulators (GQAMs / Edge QAMs)

• QAMs receive MPEG information encapsulated as UDP streams* from the NetCrypt™ Bulk Encryptor

• QAMs request and terminate IP multicasts, and modulate the content as MPEG transport packets onto an RF carrier

GQAM

SDV Elements STB Client

• The STB requires a SARA (S-A resident applications) OS version that supports SDV

• Provides customer interface for switched services• Stores last known Mini-Carousel data• Registers all user activity with SDV Server

Settop with SDV Client

Section:Setup and

Signal Flow

SDV Components

Provisioning and Channel Change

Major SDV Channel-Change Scenarios

HFCNetwork

VideoContent

IP Network

ControlIP Network

QPSK

End-to-End System Solution and Integration

6.) GQAM: Session-based modulator with IP/GbE input, Issues IGMP message to “join” multicast group for SDV, and may also handle unicast VOD streams

1.) DCM / Staging Processor: Aggregates multiple MPEG sources, Clamps VBR programs to CBR, Converts MPTS to SPTS, Encapsulates MPEG into IP over GbE output, Addresses unicast IP for encrypted programs and multicast IP for unencrypted, and Performs DPI for ad insertion

2.) DNCS with SDV licenses

3) SRM: Allocates QAM resources for different applications including VOD and SDV, and Reclaims bandwidth from Servers as needed

7.) Switch/Routers: Standards-based with IGMPv3 SSM, Switches streams to appropriate GQAMs, and Maintains IGMP membership tables

Setup Flow - SDV Components

4.) NetCrypt Bulk Encryptor: IP network-attached encryption, Up to 4 Gbps, and Addresses multicast IP for distribution

DNCS

SDV Server

GQAM

SDV Client(on STB)

NetCrypt

ContentSources

DCM

8.) SDV Client: Provides customer interface for switched services, Stores last known Mini-Carousel data, and Registers all user activity with SDV Server

5.) SDV Server: Intel Server running Linux OS, Requests bandwidth and shell sessions from the SRM Manager, Binds shell sessions to multicast content, Distributes Mini-Carousel for topology, client configuration, and updated tuning information and Processes channel change requests

5) SDV Mgr: User interface in DNCS for control and configuration of the SDV Servers and service group settings

Signal FlowMajor SDV Channel-Change Scenarios

SDBProgramSelectConfirm

SDBProgramSelectRequest

DNCS“SRM”

SettopQAMSDV

Server

ServerInteractiveSessionRequests

ServerInteractiveSessionConfirms

QAM Shell Session Setups

SDBProgramSelectRequest/Confirm

Case 1. Program already to Service Group and in Mini-carousel

Case 2. Program already to QAM chassis for another Service Group

Case 3. Bandwidth available on QAM that is not member of that multicast group

Router

SDBProgramSelectConfirm

SDBProgramSelectRequest

Bind to multicast w/ bit-rate

IGMPv3 “Join”

Case 4. No bandwidth available on current QAMs. SDV server must request additional bandwidth from SRM

SDBProgramSelectRequest

IGMPv3 “Join” SDBProgramSelectConfirm

Bind to multicast w/ bit-rate

Bind to multicast w/ bit-rate