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Given by NPAC Team at SC95 Tutorial on Web Technologies on December 4,95. Foils prepared December 2,95
Abstract * Foil Index for this file

See also color IMAGE
This covers basic issues underlying digital video including:
Video Compression with MPEG Standards
Some commercial Internet Examples: RealAudio and Xing
Home delivery with ADSL and ISDN
Windows NT as an impressive server basis
NPAC VoD and ATM testbed is surveyed
Video Indexing including Closed Caption Text

Table of Contents for full HTML of Video Server,Delivery and Compression Technologies

1 Tutorial on Current and Future Web(NII) Technologies -- Digital Video Services
2 Abstract of Digital Video Presentation
3 Digital Video: The Basics
4 Digital Video: The Basics
5 Digital Video: Myths and Facts
6 Digital Video: Middle Ground
7 Video Compression (1)
8 Video Compression (2)
9 Video Compression (3)
10 MPEG-1 vs. MPEG-2
11 Video Compression (4)
12 Encoding and Content Preparation
13 Decoders: Current Technology
14 Digital Video: Network Delivery Options
15 Media Servers: RealAudio server
16 Media Servers: Xing StreamWorks
17 Network Delivery: "last mile" Alternatives
18 Network Delivery: "last mile" Alternatives
19 Interactive Video on Demand Servers
20 VoD Testbed in NPAC
21 Elements of a Video Server
22 LAN Video Servers in NPAC
23 NPAC Video on Demand ATM Testbed
24 nCUBE Video on Demand Server
25 Interactive Video on Demand Servers
26 Architecture of Windows NT
27 Architecture of Windows NT
28 Windows NT I/O and Networking

This table of Contents Abstract

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Foil 1 Tutorial on Current and Future Web(NII) Technologies -- Digital Video Services

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Supercomputing 95
Monday December 4,1995
San Diego Convention Center
NPAC
Geoffrey Fox, Wojtek Furmanski, Marek Podgorny with
Gang Cheng, Roman Markowski
Syracuse University
111 College Place
Syracuse
NY 13244-4100
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Foil 2 Abstract of Digital Video Presentation

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
Full HTML Index
This covers basic issues underlying digital video including:
Video Compression with MPEG Standards
Some commercial Internet Examples: RealAudio and Xing
Home delivery with ADSL and ISDN
Windows NT as an impressive server basis
NPAC VoD and ATM testbed is surveyed
Video Indexing including Closed Caption Text
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Foil 3 Digital Video: The Basics

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Analog video:
  • Each frame represented by an analog wave form.
  • Composite signal carries all video components: color, brightness, sync..
  • Component video separates video components (S-VHS, RGB...), component signals still analog
  • Main weakness: generational quality loss
Digital video formats
  • D1, D2, D3, D5, Digital Betacam....
  • All these formats still use magnetic tape as the storage medium
  • Very little compression is used for these digital video formats
  • Main weakness: only sequential access ("linear editing")
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Foil 4 Digital Video: The Basics

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Computer digital video:
  • a data stream in which a compressed representation of series of images and of the associated audio are stored in an interleaved fashion so that each pixel or sound sample is represented by a series of bits.
  • the data streams are stored on the CD-ROMs or on the hard disk as standard files.
Digital video quality factors:
  • frame rate: 24-30 frames/s (48-60 fields/s) common for analog video. "Good" digital video ranges from 10 to 30 frames/s
  • spatial resolution: analog standards 768x484 (NTSC) or 768x576 (PAL). "Good" digital video: 320x240
  • color resolution: not easily defined for analog video as not all RGB colors are "legal" NTSC colors. Digital representations of the analog video use 4:2:2 subsampling which results in color resolution somewhat lower than 24 bit color. Digital video does not limit color resolution
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Foil 5 Digital Video: Myths and Facts

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Playfield for extremists
  • Popular research approach: current hardware and software infrastructure inadequate for digital video or other continuous media. Packet networks and IP protocols not useful; need ATM AAL and radically new protocols to ensure quality of service, bandwidth provisioning, tight real-time protocols and scheduling.
  • Enthusiasts claim: Internet ready for digital video - let's go MBONE!
  • Telco's and CATV: take a disk farm or a bunch of real-time MPEG encoders and connect to hybrid fiber coax or ADSL.
Reality check:
  • ATM technology not ready, QOS not implemented, AAL1 protocol hardly available.
  • Internet certainly not ready for video unless 1 frame/s deemed useful. MBONE just a demo of IP multicast technology.
  • Telco's and CATV trials plagued by performance and scalability problems. VDT technology functional but server technology far behind.
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Foil 6 Digital Video: Middle Ground

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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For carefully designed systems, efficient implementation of network digital video is possible today. Existing shared medium LAN infrastructure (both hardware and software) can be used and integrated with ATM switched networks and with WAN technologies. IP framework offers sufficient initial support for serious VOD projects. QOS will be implemented using new RSVP protocol.
Internet ready only for very low bandwidth digital video. Both infrastructure improvements and new software is needed for Internet video becoming reality.
For large commercial or educational digital video distribution systems significant basic research is needed. The best architecture of a scalable video server is not known at present, nor are the proven guidelines to build such an installation available.
Web references: http://spiderman.bu.edu; http://www.tnc.lcs.mit.edu; http://elmer-fudd.cs.berkeley.edu; http://vod.isl.goldstar.co.kr; http://www.netwideo.com; http://www.npac.syr.edu
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Foil 7 Video Compression (1)

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Frameworks (1):
  • Video for Windows: Microsoft platforms, proprietary standard, .AVI file format, codecs: Indeo, Cinepak, M-JPEG, MPEG
    • SW and HW decoders, DCI support, MCI application interface, disk oriented
    • Advantages: easy to integrate with applications; disadvantages: network support requires non-trivial custom programming
    • Quite spectacular new Indeo Video Interactive wavelet-based codec...
  • QuickTime: Apple (secondary: Windows XX, SGI), proprietary standard, general isochronous delivery framework, codecs: JPEG, Cinepak....
    • Modest video quality, no explicit network support (integration with OpenTransport pending), SW only
    • Popular Video CD/Games technology, spectacular QT-VR extension
    • Limited acceptance - rarely considered as professional network digital video platform
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Foil 8 Video Compression (2)

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Frameworks (2):
  • Motion JPEG: not really a standard. High-quality frame-preserving codec, relatively low compressions rates
    • Leading technology for non-linear video editing (AVID), broadcast quality video, mostly SW but HW decoders emerging. AvidNet (a.k.a. MediaNet) network support
    • Limited standardization. Recent initiatives: Digital Media Language (DML) and Open Media Framework (OMF)
  • MPEG: both a codec and delivery framework; international standard; Telcos and cable TV industry pick for network digital video
    • complex codec using both intra and inter frame compression; encoding very CPU intensive; encoding algorithm not part of the standard, both Constant Bit Rate and Variable Bit Rate supported; variable quality up to HDTV
    • system stream carries both video and audio (6 channels for MPEG-2); suitable for both disk and network delivery; difficult to handle in interactive titles
    • 3 different flavors: MPEG-1, MPEG-2, MPEG-4
    • Web reference: http://www.crs4.it/luigi/MPEG/mpegfaq.html
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Foil 9 Video Compression (3)

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * Critical Information in IMAGE
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MPEG flavors:
  • MPEG-1 and MPEG-2 use the same base technology but begin with different initial resolutions
    • 3 types of frames: I-frames (a.k.a. key frames) use only intraframe compression akin to JPEG; P-frames and B-frames do not contain pixel information but operational description of frame content. To decode a P-frame, decoder needs frames behind; for B-frames both look behind and ahead is needed
  • MPEG system stream: video and audio interleaved in a complex fashion
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Foil 10 MPEG-1 vs. MPEG-2

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * Critical Information in IMAGE
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Is MPEG-2 going to replace MPEG-1?
  • No. MPEG-1 and MPEG-2 have been targeted at different bit rates!
Initial frame
sizes:
CCIR 601: 720x480
SIF: 352x240
MPEG-1: decimation
prior to encoding
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Foil 11 Video Compression (4)

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Futures:
  • MPEG-4:
    • currently in application identification phase. Standard expected end of 1998. Intended for very narrow bandwidth.
    • Compression class A (10 kbps), class B (48 kbps), class C (320 kbps)
    • Probably will include speech and video synthesis (compare to MIDI) and artificial intelligence technologies to build high fidelity pictures from minimal data.
    • Compression class E (synthetic images)
    • Certain probability that the H.263 standard will become heart of MPEG-4
  • Wavelets:
    • Most recent data compression technology discussed elsewhere in this tutorial. Potentially can achieve 300+:1 video compression rates in relatively simple algorithmic way. Superiority over MPEG for low bit rates is a point of controversy. Used in Indeo Video Interactive.
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Foil 12 Encoding and Content Preparation

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Video for Windows: easy access to inexpensive capture, encoding, and editing tools. HW assisted real-time encoders available in <$500 price range (Intel Smart Recorder). Non-linear editors (Adobe's Premiere, ATI's Media Merge, Digital Media's Splice...) and video production tools (Assymetrix, HSC Software, Macromedia...).
QuickTime: less abundant but readily available products. Many products available for VfW have a QT version.
Motion JPEG: HW encoders mostly available for UNIX workstations (Parallax, SGI). At the high end, AVID products provide superb, professional capture, encoding, and editing tools. System of choice for postproduction houses. Unmatched quality and functionality.
MPEG: HW real time encoders pricey (MPEG1) or very pricey (MPEG2). Non-linear editing systems just coming to the marketplace. . HW encoders adequate for educational applications, SW encoders used for broadcast quality digital material.
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Foil 13 Decoders: Current Technology

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * Critical Information in IMAGE
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Software decoders available for all codecs; performance rapidly getting better. Very satisfactory Indeo Video Interactive (Intel) and MPEG (Xing Technologies, CompCorp) players.
  • 90+ MHz Pentium CPUs can decode MPEG SIF in real time.
  • However, full screen 30 fps video requires HW support.
Hardware playback options:
  • MPEG: (1) decoder cards for external monitors only; (2) MPEG decoder cards using VGA feature connector to integrate MPEG & VGA; (3) proprietary integration of MPEG and VGA (VESA Media Channel)
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Foil 14 Digital Video: Network Delivery Options

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Most of the digital video frameworks are local mass storage (CD-ROM, hard disk) oriented. So is standard Web video technology (download first, then play). Telco's and CATV technology is mostly not IP-based. Interactive TV standards (DAVID - Digital Audio/Video Interactive Decoder) seem orthogonal to Web technology at present and will not be discussed in this tutorial.
Network delivery options: shared file access and audio/video servers
  • Shared file access: NFS, Samba (NetBios (SMB) servers for Unix) , AppleShare, LAN Manager .......
    • disadvantages: not really continuous media protocols, some slow (NFS, AppleShare), no development path for QOS support, security problems, do not fit Web model although may be useful when used internally on LANs.
  • "middle of the road" solutions like NetWare Video.
  • Audio/video servers: custom servers providing real time continuous media streams.
    • Examples: RealAudio Internet audio server, Oracle's Media Server, Xing's StreamWorks, Intel's/CNN CNN at Work, NPAC video server
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Foil 15 Media Servers: RealAudio server

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
Full HTML Index
RealAudio (http://www.realaudio.com) is a suite of programs to produce, serve, and play audio files over the network. The playback is instantaneous - no file downloading to local disk is involved.
  • Software: custom player (free software) is needed to use Real Audio. Encoder is available for a nominal fee or as a part of server package
  • Architecture: an independent compressed audio server (ppn:/) delivers the audio. An audio link on a Web page only provides a URL of the audio server and audio file. The audio player is capable of locating, pooling, and interactively playing audio files from any server on the net even without an http browser.
  • RealAudio files require only 10 kbit/s to play and can be accessed using POTS. Compression technology is proprietary. Audio quality corresponds to AM radio. Encoder converts all popular audio file standards.
  • dozens of Web sites use RealAudio, including large broadcasters.
RealAudio represents a new wave of real-time, interactive Web services for continuous media.
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Foil 16 Media Servers: Xing StreamWorks

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
Full HTML Index
StreamWorks (http://www.xingtech.com) is a set of programs to produce, serve, and play both audio and video files over the network.
  • As for RealAudio, playback works in the stream mode.
  • The same market strategy: free players, expensive servers
  • Architecture: an independent streaming audio/video server. Integration with Web via CGI technology: more flexible than RealAudio
  • Compression: MPEG 1 for both audio and video. Multirate audio streams. Video streams with bit rates down to ISDN rate.
  • The quality we observed warrants a qualification as a working prototype.
    • Internet bandwidth limitations and absence of QOS measures make implementation of the stream servers difficult
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Foil 17 Network Delivery: "last mile" Alternatives

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Asymmetric Digital Subscriber Line (ADSL) - UTP-3 carrier
  • ADSL employs adaptive signal processing to compensate for signal distortion. Requires VLSI electronics on both ends.
  • Provides asymmetric bandwidth
  • In initial state of deployment (Bell Atlantic, Washington, DC)
  • Probably will support ATM transport via embedding cells in the synchronous 6.3 Mbps stream
  • Suitable for high bandwidth video codec like MPEG-1 or MPEG-2
  • IP over ADSL possible but very little testing done
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Foil 18 Network Delivery: "last mile" Alternatives

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Integrated Services Digital Network (ISDN) - UTP-3 carrier
Two standard interfaces: Basic Rate Interface (BRI) and Primary Rate Interface (PRI), symmetric bandwidth.
  • BRI: 2 B channels (64 kbps each) + 1 D channel (16 kbps), full duplex
  • PRI: 23 (30 in Europe) B channels + 1 D channel (64 kbps), full duplex. PRI also supports H channels: H0 - 384 kbps, H10 - 1472 kbps etc.
D channel used for out-of-band control.
Inverse multiplexing is a standard feature of ISDN - flexible bandwidth provisioning.
Both circuit mode and packet mode are supported.
IP support via Point-to-Point (PPP) protocol or via proprietary solutions.
BRI service at best marginal for video; sufficient for teleconferencing using H.261 or H.263 protocols.
MPEG-4 (whatever it will be) will probably provide an acceptable solution for video over ISDN lines.
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Foil 19 Interactive Video on Demand Servers

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Application integration: Video contents indexing
  • Line 21 (closed caption) services decoded from the analog video source during the digital encoding process
    • Automatic text parsing, time stamping and translation to file offsets
    • Stored in a full text searchable database, integrated with server management data structures.
    • Provide random access to the associated video contents
  • Continuous speech recognition on the audio layer is a natural extension (BBN speech recognition engine)
Application integration: Video clients
  • web - controlled video clients available for a number of platforms
Application focus: education and professional training and integration with information systems (see Living Schoolbook project overview later during SC'95)
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Foil 20 VoD Testbed in NPAC

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Data acquisition subsystem
  • analog video formats: VHS, S-VHS, Betacam
  • digital video formats: MPEG-1, Indeo, M-JPEG
  • closed caption decoding for video indexing
Video servers: Windows NT and Unix SMPs, nCUBE2 MPP
  • disk storage of ~250 GB
Video distribution options
  • switched ethernet to ATM to switched ethernet, encapsulated bridging
  • ATM to ATM
  • ATM to switched ethernet, LAN Emulation
  • Living Schoolbook wide area ATM network (NYNET)
Video clients: SGI workstations, PCs under Windows
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Foil 21 Elements of a Video Server

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * Critical Information in IMAGE
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Foil 22 LAN Video Servers in NPAC

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Interactive VOD servers implemented in NPAC: concurrent interactive IP based VOD servers
  • PC based Windows NT server (target: small corporate video installations): up to 15 MPEG-1 streams from single CPU/single disk
  • UNIX based server (target: larger corporate video and educational installations): scalable to few tenths of concurrent video streams
  • MPP server (target: community video servers): scalable to 100s of concurrent video streams
Common features: unified server protocol; video format independent; interactive, support for HW and SW decoders, high performance via multithreading and asynchronous I/O
Server access (search) and server management layer implemented via integration with web and relational database technology
Web reference: http://www.npac.syr.edu/projects/vod
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Foil 23 NPAC Video on Demand ATM Testbed

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * Critical Information in IMAGE
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Foil 24 nCUBE Video on Demand Server

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * Critical Information in IMAGE
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Foil 25 Interactive Video on Demand Servers

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Challenging research issues:
  • Design of scalable SMP and MPP VOD architectures
    • Balanced and scalable CPU processing power, internal bandwidth, disk I/O, and network I/O
    • Data allocation procedures and performance impact
    • Multistage buffering schemes
    • Server management: data load, tertiary storage, hot cache
    • Scalability evaluation of SMP and MPP architectures for VOD
    • Criticality of server components performance for scalability and performance of entire system: simulation studies
    • Distribution network architecture and performance issues
    • System integration, cost, and maintenance issues
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Foil 26 Architecture of Windows NT

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * Critical Information in IMAGE
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Foil 27 Architecture of Windows NT

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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Combined layered and modular structure - extensibility
Flat 32 bit paged memory model
Multithreaded system with preemptive scheduling
Environment subsystems emulate other operating systems (Windows, Windows'95, MSDOS, OS/2, POSIX)
Environment subsystems separated form the NT kernel by NT Executive
Executive provides scheduling, synchronization, interrupt processing and thread and memory management
Hardware dependencies isolated by the hardware abstraction layer - easy porting process
Priviledged mode extension (device drivers, file systems) coordinated by Executuve but talk directly to hardware
Supports SMP architectures
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Foil 28 Windows NT I/O and Networking

From Video Server,Delivery and Compression Technologies SC95 Tutorial on Web Technologies -- December 4,95. * See also color IMAGE
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File descriptors and network sockets are objects in NT Executive
NT supports asynchronous disk I/O via callback functions and disk I/O API
  • Video server design exploits concurrency using asynchronous I/I
NT also supports asynchronous network I/O!
  • On data arrival, a message is sent to message queue
  • Messages retrieved by polling mechanism
  • On receipt of the message client reads from the network. The mechanism is not blocking
  • Dual buffering combined with asynchronous I/O hides disk and network latencies.
Northeast Parallel Architectures Center, Syracuse University, npac@npac.syr.edu

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