Introduction and Architectures

1. INF 5070 – Media Storage and Distribution Systems: Introduction and Architectures 25/8 - 2003

2. Overview • Intro • about the course • multimedia applications and challenges • Architectures • Media (Video) on Demand • Machine internals • Video server structures • Examples

3. INF5070:The Course

4. Lecturers in INF5070 • Carsten Griwodz • email: griff @ ifi • room: 3203 • Pål Halvorsen • email: paalh @ ifi • room: 3309

5. Network Network Network Network Content of INF5070 – I architectures file systems media data distribution protocols resource scheduling topologies

6. Content of INF5070 – II • System architectures(server and system designs) • Media data(wire and file formats, codecs) • Media characteristics and user behavior (processing multimedia data, user interactivity) • Resource management(CPU and memory management)

7. Content of INF5070 – III • Protocols with and without Quality of Service (QoS)(specific and generic QoS approaches) • Storage systems (management of multimedia files, retrieval) • Distribution(use of caches and proxy servers) • Adaptation, mobility and Peer-to-Peer(various clients, different amount of resources)

8. Content of INF5070 – IV • Student assignment (will be presented more in-depth later): • (IXP programming) • read related article • assignment must be reported and presented to the class at the end of the course

9. Goals of INF5070 • Media servers and distribution system • media characteristics • architectures • system support • protocols • distribution mechanisms • … • Be able to evaluate any combination of these mechanisms

10. Pensum INF5070 • Approved presentation of student assignment • Oral exam (1-3/12): • all transparencies from lectures • content of own student assignment

11. Applications and Challenges

12. Applications • Multimedia enriches the user interface giving new applications • Broadcast – server is only VCR substitute (e.g., MTV Europe) • Media-on-Demand (MoD) • Video-on-Demand (VoD) (e.g., Bell Atlantic  ~1000 users, 700 choices) • News-on-Demand (NoD) (e.g., CNN, BBC  web today, BAD quality) • Learning-on-Demand (LoD) (e.g., the OMODIS project) • Virtual worlds (typically live, not on-Demand) • video conferencing (e.g., USIT’s electronic classroom) • games (e.g., Quake, …)

13. Requirements • Application • QoS – time sensitivity • resource capabilities – support interactive streaming of multimedia content • Business • scalability • reliability • Architectural • topology • cost vs. performance

14. Technical Challenges • User end system: • real-time processing of streams (1000 MIPS for an MPEG-II decoder) • request/response delay (< 150 ms for videophones) • high data rates, e.g., MPEG-II DVD quality: • average video rate of 3.5 Mbps • max. total data rate of 10.08 Mbps • max. user rate of 11.08 Mbps (all included like control signals) • Storage • real-time retrieval of contiguous media streams, e.g.: • 4000 movies * 90 minutes * 15 Mbps (HDTV) = 40.5 TB • 2000 CDs * 74 minutes * 1.4 Mbps = 1.4 TB • Network • real-time transport of contiguous media data

15. Media-on-Demand (MoD) Systems • Classification parameters • structure of movies • interaction • presentation form • Common directions • analog  digital media • distribution  interaction • media broadcasting  media multicasting  personalized media • linear movies  branched movies  variable movies • Evolution • broadcast - traditional, no user control • pay-per-view - limited interactivity • quasi MoD - distinction into user groups, limited timely control • near MoD - same media distributed in intervals • true MoD - full user control, VCR capabilities, bidirectional

16. Television (Broadcast) time channels sender receiver(s) • analog or digital • traditionally, one program per channel • analog use frequency division multiplexing only • digital may additionally use time division multiplexing inside one frequency (several programs per channel) • linear movies

17. Near Video-on-Demand (NVoD) time channels sender receiver(s) • analog or digital broadcasting • one program over multiple channels • time-slotted emission of the program • linear movies

18. (True) Video-on-Demand (VoD) time movies sender receiver(s) • digital uni- or multicasting • control channels • linear movies

19. Comparison: NVoD vs. TVoD

20. “Interactive Vision” time movie sender receiver(s) • digital uni- or multicasting • control channels • fixed non-linear movies

21. “Cyber Vision” time sender receiver(s) • digital uni- or multicasting • control channels • variable non-linear “movies”, e.g., • - games, virtual reality, …

22. Application Classification Overview Cyber Vision variable Interactive Vision movie structure branched HDTV VoD digital TV NVoD linear presentationform unidirectional VIDEO interaction analog bidirectional

23. Media (Video) on Demand

24. Challenges • VoD in LANs is solved: OVERPROVISIONING works • established in studio business • established in hotel/hospital/plane/… business • VoD in WANs • goals: • network-based distribution of media content to consumers • bring control to users • assumptions: • overprovisioning of resources will NOT work • no central control of delivery system • programs: • need for interoperability – not from a single source • need for co-operative distribution systems • amount of data: • estimated 65000 movies made in 1995  260 TB MPEG-2 data • additionally, data from TV-series, sport clips, news, … • historically: • much attention as “interactive TV (ITV)” some years ago • many (not successful) field trials • now: interest turned to Internet-based systems

25. ITV Network Architechture Approaches • WAN backbones • SONET • ATM • Local distribution network • ADSL (asymmetric digital subscriber line) • FTTC (fiber to the curb) • FTTH (fiber to the home) • HFC (hybrid fiber coax) • Internet WAN • Diffserv over MPLS (multi-protocol layer switching) • point-to-point Gbps ethernet • Internet local • IP over the old distribution networks ATM / SONETbackbone network wireless Internet based systems ATM telephone cable

26. Concerns: Internet-Based VoD Systems • Can technical problems be mastered? • broadband communication to every home • user-friendly end systems • server technology • Market success? • what prices will consumers accept? • high equipment (HW & SW) costs • data costs • will it be competitive? • to existing TV programs • to video rentals • what is the consequence of ITV field trials in USA and Europe? • no big success • only a few private consumers willing to participate • trials were cancelled or switched from TV-based to PC-based platforms

27. Driving Forces • Hardware/software (IT) companies • computer (e.g., IBM, HP, Sun, Microsoft, …) • consumer electronics (e.g., Sony, Philips, …) • Network companies • telephone (e.g., Telenor, Telia, BT, AT&T, …) • cable TV (e.g., UPC, Time-Warner Cable, …) • Content companies • media • movies (e.g., Time-Warner, Disney, Paramount, Leo Kirch, …) • TV programs (e.g., NRK, TV2, TV3, RTL, …) • hyper media information bases (e.g., Springer, Bertelsmann, …) • home-shopping (e.g., Quelle, OTTO, …) • video games (e.g., Nintendo, Sega, Microsoft, …)

28. VoD Deployment Status – I • Digital Video Broadcast (DVB) • no VoD • cable, antenna, or satellite broadcast • some NVoD scheduling approaches (e.g., TV 1000) • Digital Audio-Visual Council (DAVIC) • defines interfaces only • no standardization of algorithms for interoperation • Internet Engineering Task Force (IETF) • currently no large-scale, wide-area video distribution • sporadic use of cooperative web caching • starting AV caching considerations • defines protocols and inspires interoperability testing Broadcast world suited for Near VoD Broadcast world suited for True VoDInternet world suited for True VoD MPEG 4 suited for Interactive Vision

29. VoD Deployment Status – II

30. VoD System Architecture local distribution network backbone network local distribution network local distribution network

31. master servers regional servers local servers end-systems VoD Storage Hierarchy completeness of available content • Popularity of movies:not all are equally popular – most request directed to only a few (Zipf distribution) • Use hierarchies: • Straight forward hierarchy: • popular videos replicated and kept close to clients • locality vs. communication vs. server costs

32. VoD Components • Servers • Networks • backbone • local networks • Intermediate nodes • routers • proxy cache servers • replica servers • End-systems • PCs • TV sets with set-top boxes

33. Traditional Server Machine Internals

34. application file system communication system General Operating System Structure and Data Path user space kernel space

35. Example: Intel Hub Architecture (850 Chipset) – I Intel D850MD Motherboard: RDRAM connectors CPU socket RDRAM interface system bus hub interface PCI bus Memory Controller Hub I/O Controller Hub PCI connectors

36. application file system communication system disk network card system bus (64-bit, 400/533 MHz) I/O controller hub memory controller hub file system communication system RAM interface (two 64-bit, 200 MHz) application hub interface (four 8-bit, 66 MHz) network card PCI bus (32-bit, 33 MHz) disk Example: Intel Hub Architecture (850 Chipset) – II Note:these transfers only show data movement between sub-systems. Additionally, data touching operations within a sub-system will require that data is moved from memory and to the CPU, e.g.: - checksum calculation - encryption - data encoding - forward error correction Pentium 4 Processor registers cache(s) RDRAM RDRAM RDRAM RDRAM PCI slots PCI slots PCI slots

37. application CPU CPU file system communication system L1 L1 disk network card (four 64-bit, 400 MHz) (eight 32-bit, 400 MHz) (four 64-bit, 400 MHz) RAM RAM RAM GX bus (two 32-bit, 600 MHz) PCI busses (32/64-bit, 33/66 MHz) RIO bus (two 8-bit, 500 MHz) Example: IBM POWER 4 POWER 4 chip core interface switch L2 fabric controller file system L3 memory controller GXcontroller L3 controller communication system application network card PCI slots remote I/O(RIO) bridge PCI host bridge PCI-PCI bridge disk PCI slots PCI host bridge PCI-PCI bridge Note:Again, data touching operations add movement operations

38. Memory Hierarchies • We can’t access the disk each time we need data • Typical computer systems therefore have several different components where data may be stored • different capacities • different speeds • less capacity gives faster access and higher cost per byte • Lower levels have a copy of data in higher levels • A typical memory hierarchy: tertiary storage (tapes) price speed secondary storage (disks) main memory capacity cache(s)

39. offline tape 1015 1013 magnetic disks 1011 online tape 109 main memory 107 105 cache 103 10-9 10-6 10-3 10 Storage Costs: Access Time vs Capacity typical capacity (bytes) access time (sec) from Gray & Reuter

40. 104 cache main memory online tape 102 magnetic disks 100 10-2 offline tape 103 10-9 10-6 10-3 10 Storage Costs: Access Time vs Price dollars/Mbytes access time (sec) from Gray & Reuter

41. Internal Server Design • Stream retrieval from disk and push to network • buffer requirements • bus transfers • CPU usage • concurrent streams (can be merged??) • storage (disk) system: • scheduling – ensure that data is available in time • block placement – contiguous, interleaving, striping • … • Stable operations: • redundant HW • multiple nodes • Much more, e.g., caching/prefetching, admission control, …

42. Video Server Structure

43. Internal content directory: External content directory: HP, DEC, Novell, … switch network attachment switch switch content directory/memory management switch switch file system switch switch storage management IBM TigerShark switch switch controller switch switch storage device Video Server:Server Components & Switches [Tetzlaff & Flynn 94]

44. network attachment memory management file system storage management controller storage device Video Server Components incomingresolve request incomingdata request delivered resolution delivered data network attachment content directory control/application server data server

45. data control Video Server:Simple General Server Architecture [Sitaram & Dan 00] • Storage subsystem: • stores data • different devices • Processor subsystem: • executing part • management and operations • Network subsystem: • transmit MM data storagesubsystem processor subsystem network subsystem control server data server clients application server • Data server: • data delivery • “specialized file system” • buffer manager • data importer/exporter • Application server: • user interface • billing • content database • user database • service gateways • Control server: • administrator • admission control • optimization

46. data data Network Network content content Video Server:Directory Access & Data Retrieval • Two-step retrieval: • “problem”:resource management • Request redirection: • “problem”:client gets data from another machine

47. server server client client Video Server:Directory Access & Data Retrieval • Pull model: • client sends several requests • deliver only small part of data • fine-grained client control • favors high interactivity • suited for editing, searching, etc. • Push model • client sends one request • streaming delivery • favors capacity planning • suited for retrieval, download, playback, etc.

48. Single server easy to implement scales poorly Partitioned server users divided into groups content : assumes equal groups location : store all data on all servers load imbalance Network Network Network Video Server:Server Topology – I

49. Externally switched servers use network to make server pool manages load imbalance(control server directs requests) still data replication problems (control server doesn’t need to be a physical box - distributed process) Fully switched server server pool storage device pool additional hardware costs e.g., Oracle, Intel, IBM data Network data data control data I/O switch Network data control Video Server:Server Topology – II

50. Video Distribution Server:Typical In the Internet Today • Push systems(pull in video editing/database systems) • Traditional (specialized) file systems – not databases – for data storage • No in-band control (control and data information in separate streams) • External directory services for data location(RTSP/control server + data pump) • Request redirection for access control • Single stand-alone servers  (fully) switched servers