An Overview of the TiVo Service

Transcription

1 An Overview of the TiVo Service Jim Barton CTO TiVo Inc. 4/12/01 1

2 Content Distribution Is Changing Lots of content to distribute Lots of broadcast bandwidth Slow increase in two-way bandwidth Lots of local area bandwidth in the home Lots of computing power in the home Massive amounts of cheap storage in the home Time-shifting and off-peak download using local storage will be a primary way to distribute content 4/12/01 2

3 Implications of This Change Learning about interesting content gets harder Ease of navigation and selection becomes critical Data describing content is a critical resource Number of users of content grows much larger Move to Open Standards and Systems necessary One-to-One distribution One-to-Many distribution Manufacturing Copies Managing Caches Centralized control Distributed Control Transport security + System security + Network Security 4/12/01 3

4 Pointers to Content: Big Meta-Data Broadcast: Program guide data Anything that can be broadcast and recorded <Description, Channel, Time, Duration, Encoding> Internet: Content guide data Anything that can be downloaded and decoded <Description, Server, Name, Access Rights, Encoding> Structuring is Critical Relationships between pointers, e.g., series, sequel, album, portfolio, prolog, version, ordering, genre, preference, suggestion, 4/12/01 4

5 Essence of the TiVo Service Distribute and Aggregate meta-data Manage a local database of what is available Navigate the meta-data Local database means fast and powerful search Promotion and targeting is fast and direct Measurable reaction and direct response Manage Caching of the content Using appropriate security, rights Record content and report transactions Anonymous reporting on use and behavior 4/12/01 5

6 End-to-End Service Architecture Clients and Partners Tribune Media Services Raw Data Broadcast Carousel Local TiVo Meta- Data Database Reporting and Data Mining Reduced, Compressed, ID assignment EPG Slice and Dice TiVo Engineering Software Updates Global TiVo Meta-Data Database Slicing Distribution and Replication Servers Profiles, anonymous usage data Telephony Servers The Cloud Version/ Dependency/ ID Authoring Meta-Data Key assignment/ Serial # recording Manufacturing Billing and Subscriber Management System Customer Calls Customer Support Info Bills, payments and Direct Marketing Upload Staging and Dispatching Servers Replicate: - Auth. Information - Common data - Head-end specific EPG Consolidate: - Back-channel data - Call performance info 4/12/01 6

7 Scope of the Service 150,000 subscribers (Jan 31) 4.5 Petabytes under management (10 15 ) 5.1 Terabytes downloaded daily 7 models in retail, 4 manufacturers 5 software releases since first product ship Average of 2 shows recorded per TiVo per day 90% of viewers skip 100% of commercials 4/12/01 7

8 TiVo Design Foundations Broadcasting is fundamental technology Ultimate scalability Fastest increase in bandwidth Go to where the content is! Network connections for meta-data Minimal dedicated bandwidth Batch transfer whenever possible Moving pointers to content, not content No dependency on online access Split processing chores between service and receiver Viewer experience never disrupted by server problems 4/12/01 8

9 E-Distribution Cost Curves Total $ to Deliver On-Demand Delivery (Peak loading limitation) Time-Shifted Delivery (Optimal bandwidth use) Time-Shifted Broadcast (Address any number of Users) Number of Users Addressed 4/12/01 9

10 Design Foundations 2 TiVo is a System Integrator Open standards wherever possible Aggressive Design, not aggressive Technology Use Best Practices in System Design Modern disk operating systems and tools Rolling Thunder : preserve software investment Lots of clients, as fast as possible 4/12/01 10

11 Design Foundations 3 The Hard Disk Rules Everything Hardest component to manage Heat, noise, vibration, performance,... A new focus for hardware/software design What happens when the power fails? Distributed Data Management is Hard! Millions of individual items in each client Each client personalized to viewer Manage versions, expiration, cleanup 4/12/01 11

12 Design Foundations 4 Service should be invisible Must disappear as a pencil does when writing Effortless to use, no management needed Television never crashes, always works perfect 4/12/01 12

13 Simple Video Recorder Model Basic DVR TV Source: Analog (NTSC/PAL) Digital (DirecTV, DBS, 1394) Buffer Memory TV Output: Analog (NTSC/PAL) Digital (1394,RF) Input Section MPEG Streams Data Path and Control Logic MPEG Streams Output Section Always recording! Always playing! (up to 19Mb/s, Variable Bit Rate [VBR] or Constant Bit Rate [CBR]) Hard Disk Drive 4/12/01 13

14 Basic DVR Is Not Enough All these functions in parallel: Multiple high bit-rate VBR streams Program guide Advanced Navigation ( Foreground PVR ) search-and-record Navigation support ( Background PVR ) preferences, downloads, scheduling, Interactive Applications additive to streaming (PIP) Content download 4/12/01 14

15 Simultaneous Demands Paging (maximize system performance) Program Guide Access (acceptable response time) Broadband Download (don t overflow buffers) Persistent Storage Device Program Guide Update (match carousel update frequency) Background Program Loading (unnoticeable by viewer) Multiple Digital TV Outputs (data arrives when needed) Multiple Digital TV Inputs (don t overflow buffers) Activity Logging (max acceptable data loss) Activity Type (most critical requirement) 4/12/01 15

16 PVR Storage Requirements Support both CBR and VBR streaming Predictable performance Viewers expect TV to flow perfectly Long-term continuous operation Software controlled error management Near 100% utilization Best price/performance possible Massive capacity Lots of application data, Lots of content 4/12/01 16

17 Real-World: DirecTV/TiVo Paging (5 pages/sec burst updating working set) Program Guide Access (< 2sec to display) Broadband Download (100Kb/sec continuous) Dual Tuner (2 2-15Mb/s continuous streams) All on a 4.5K RPM slow-seek drive with only 128K disk cache! Cheap Disk Drive Advanced Program Guide (>10 Program Objects/sec) Background Tasks (indexing, scheduling, preferences, callback) TV Output (2-15Mb/s continuous stream) Activity Logging (1-4 entries/sec) 4/12/01 17

18 Inside a TiVo Receiver 4/12/01 18

19 What is TvBus? Standardized PVR services access Separates interface and implementation No linking of caller and callee together Dynamic binding through network protocol Not locked-in to a particular implementation (i.e., API) Networked client-server protocol definitions Precisely defined in machine-readable files (IDL) Compiled to language bindings (JavaScript, C/C++) Client, server can be anywhere Local, in another device, at head end, somewhere on the net, etc. 4/12/01 19

20 Application Services Multi-Service Architecture Ex.: keyboard, remote, screen, joystick, etc. TvBus: TCP/IP Services Protocol Resource Arbitrator PVR Service Client Application Other Services PVR Service Infrastructure Client Service Interface Manager JavaScript Service Interface Other Services And Interfaces HTML4.0 + Javascript Rendering and Layout System Services Media Object Model (MOM) Persistent Object Store Meta-Data Management & Navigation Direct OS/GFX Access Software ToolChain: Gnu Tools, Other PD Tools Media File System (MFS) TiVo Media Kernel (TMK) Host Operating System (Linux) Hardware Drivers Disk Scheduling Subsystem Platform Vendor Supplied TiVo Basic DVR TiVo Database TiVo Personal Video Application 4/12/01 20

21 PVR Security Domains Broadcast Transport Security Designed for real-time broadcast encrypted streams Typically smart-card based (e.g., NDS, Nagra) Connection Transport Security Designed for two-way network connections Certificate based (e.g., SSL) System Security Software integrity, content protection Embedded security processor 4/12/01 21