HELP! * GREY=local Full HTML for

LOCAL foilset Second Part of Video Server Presentation for HPDC95 Tutorial

Given by Miguel del Rosario at HPDC95 Pentagon City on August 1,1995. Foils prepared July 28,1995
Abstract * Foil Index for this file

See also color IMAGE
This presentation describes issues involved in Video server and transport
As well as server technology, we cover data transport over ATM, and MPEG compression
VBR (Variable Bit Rate) and CBR (Constant Bit Rate) are two data delivery options and we present comparisons
We discuss the realAudio digital audio and extensions to video

Table of Contents for full HTML of Second Part of Video Server Presentation for HPDC95 Tutorial

1 Digital Video Servers and Video Transport
2 Abstract of Video Server Tutorial
3 Video Server Simulation
4 VBR(Variable Bit Rate) to CBR(Constant Bit Rate)
5 VBR(Variable Bit Rate) to
CBR(Constant Bit Rate) II
6 VBR(Variable Bit Rate) to
CBR(Constant Bit Rate) III
7 VBR-to-CBR Transmission- I
8 VBR-to-CBR Transmission - II
9 VBR-to-CBR Transmission -III
10 VBR-to-CBR Transmission - IV
11 Preliminary CBR versus VBR Results
12 Preliminary Results (conŐt ...)

This table of Contents Abstract

HELP! * GREY=local HTML version of LOCAL Foils prepared July 28,1995

Foil 1 Digital Video Servers and Video Transport

From Second Part of HPDC95 Video Server Presentation HPDC95 Pentagon City -- August 1,1995. * See also color IMAGE
Full HTML Index
HPDC95 Tutorial
August 1, 1995
Marek Podgorny, Miguel Del Rosario
NPAC
Syracuse University
111 College Place
Syracuse NY 13244-4100
HELP! * GREY=local HTML version of LOCAL Foils prepared July 28,1995

Foil 2 Abstract of Video Server Tutorial

From Second Part of HPDC95 Video Server Presentation HPDC95 Pentagon City -- August 1,1995. * See also color IMAGE
Full HTML Index
This presentation describes issues involved in Video server and transport
As well as server technology, we cover data transport over ATM, and MPEG compression
VBR (Variable Bit Rate) and CBR (Constant Bit Rate) are two data delivery options and we present comparisons
We discuss the realAudio digital audio and extensions to video
HELP! * GREY=local HTML version of LOCAL Foils prepared July 28,1995

Foil 3 Video Server Simulation

From Second Part of HPDC95 Video Server Presentation HPDC95 Pentagon City -- August 1,1995. * See also color IMAGE
Full HTML Index
Prerequisite to software implementation
Full nCUBE VOD server simulation
Integration of the following simulation modules:
  • Simulation kernel -- Proteus (MIT)
  • Disk simulation code (Dartmouth)
  • VOD file system simulation code (NPAC)
  • VOD network interface simulation code (NPAC)
VOD network protocol simulation
  • Opnet simulation kernel
  • Protocol stack simulation code (NPAC)
HELP! * GREY=local HTML version of LOCAL Foils prepared July 28,1995

Foil 4 VBR(Variable Bit Rate) to CBR(Constant Bit Rate)

From Second Part of HPDC95 Video Server Presentation HPDC95 Pentagon City -- August 1,1995. * See also color IMAGE
Full HTML Index
Technological Hurdles
  • Video File Server Bandwidth
    • Needs real-time O/S support for I/O (network and disk)
    • Need better understanding of parallel I/O for multimedia
    • Need faster I/O hardware, especially tertiary storage:
    • high-end tape -- 1MBps
    • low-end tape -- 100 KBps
    • optical disk -- 0.5 MBps
    • (long to very long seek times)
HELP! * GREY=local HTML version of LOCAL Foils prepared July 28,1995

Foil 5 VBR(Variable Bit Rate) to
CBR(Constant Bit Rate) II

From Second Part of HPDC95 Video Server Presentation HPDC95 Pentagon City -- August 1,1995. * See also color IMAGE
Full HTML Index
Technological Hurdles (conŐt ...)
  • ATM Switch Bandwidth
    • 1.2 Gbps => ~400 streams
    • For 1000 streams, need more switches
  • Network Protocols
    • Need real-time video protocol
    • Cable networks not desinged for interactive digital data
HELP! * GREY=local HTML version of LOCAL Foils prepared July 28,1995

Foil 6 VBR(Variable Bit Rate) to
CBR(Constant Bit Rate) III

From Second Part of HPDC95 Video Server Presentation HPDC95 Pentagon City -- August 1,1995. * See also color IMAGE
Full HTML Index
Key issue in VOD : Network Traffic
Central debate in CBR vs. VBR :
  • Is there really a performance gain in VBR?
CBR Encoding:
  • Constant bit rate, variable picture quality
  • Advantage: fixed bandwidth requirement
  • Disadvantage: picture quality degradation
VBR Encoding:
  • Variable bit rate, constant picture quality
  • Advantage: constant picture quality
  • Disadvantage: difficult to allocate network bandwidth
HELP! * GREY=local HTML version of LOCAL Foils prepared July 28,1995

Foil 7 VBR-to-CBR Transmission- I

From Second Part of HPDC95 Video Server Presentation HPDC95 Pentagon City -- August 1,1995. * Critical Information in IMAGE
Full HTML Index
Terms
    • : Total cycle time.
    • : Constant bit rate requirement (e.g., Ave. bit rate)
    • : Bits of data per cycle to satisfy consumption.
    • : Actual bit rate required for transmission.
    • : Portion of cycle time allocated to each stream.
Assumptions
  • Round-robin scheduling -- most simple. (An area of future work)
  • Fixed time slice for each stream
HELP! * GREY=local HTML version of LOCAL Foils prepared July 28,1995

Foil 8 VBR-to-CBR Transmission - II

From Second Part of HPDC95 Video Server Presentation HPDC95 Pentagon City -- August 1,1995. * Critical Information in IMAGE
Full HTML Index
Buffer Allocation Requirements
    • : Number of frames consumed by client in slot
    • : Number of frames in buffer at beginning of time slot
    • : Number of frames arriving in buffer during time slot
Continuous Media Requirement
  • True for all slots, therefore true for any slot
  • For any point during transmission, buffer must never be empty.
HELP! * GREY=local HTML version of LOCAL Foils prepared July 28,1995

Foil 9 VBR-to-CBR Transmission -III

From Second Part of HPDC95 Video Server Presentation HPDC95 Pentagon City -- August 1,1995. * Critical Information in IMAGE
Full HTML Index
Buffer Underflow Condition
  • Arriving frames less than number consumed:
  • At start, the buffer is empty :
  • For continuous media requirement, we require for any slot N
  • To prevent underflow, we buffer frames
  • where F is given by:
HELP! * GREY=local HTML version of LOCAL Foils prepared July 28,1995

Foil 10 VBR-to-CBR Transmission - IV

From Second Part of HPDC95 Video Server Presentation HPDC95 Pentagon City -- August 1,1995. * Critical Information in IMAGE
Full HTML Index
Buffer Overflow Condition
  • Arriving frames greater than number consumed:
  • At start, buffer according to underflow equation.
  • Buffer computation is in units of bits.
  • From the continuous media requirement, the required overflow buffer size is given by (modulo some timing details).
This also defines the maximum VBR-to-CBR buffer size requirement.
HELP! * GREY=local HTML version of LOCAL Foils prepared July 28,1995

Foil 11 Preliminary CBR versus VBR Results

From Second Part of HPDC95 Video Server Presentation HPDC95 Pentagon City -- August 1,1995. * Critical Information in IMAGE
Full HTML Index
Sample Description
  • 10,000 frame (approx. 15 min.) full-motion videos.
  • Compressed with MPEG-1 VBR encoder.
Bandwidth requirement and multiplexing gain
  • Using ave. bit rate as CBR transmission rate:
HELP! * GREY=local HTML version of LOCAL Foils prepared July 28,1995

Foil 12 Preliminary Results (conŐt ...)

From Second Part of HPDC95 Video Server Presentation HPDC95 Pentagon City -- August 1,1995. * Critical Information in IMAGE
Full HTML Index
Same 10,000 frame sample
Buffer requirement
  • Optimal bit rate = Ave. rate + (Ave. rate x Std. Dev. factor)
  • Reduce buffer size by selecting best CBR rate
    • (All buffer quantities in units of MBytes)
Northeast Parallel Architectures Center, Syracuse University, npac@npac.syr.edu

If you have any comments about this server, send e-mail to webmaster@npac.syr.edu.

Page produced by wwwfoil on Mon Feb 17 1997