An Overlay Network Providing Application-Aware Multimedia Services

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An Overlay Network Providing Application-Aware
Multimedia Services

• Maarten Wijnants
• Bart Cornelissen
• Wim Lamotte
• Bart De Vleeschauwer

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Problem Statement

• Increased use of real-time streaming of
  multimedia content in networked apps
• Efficient user communication
• In the future also more enhanced uses
• Consequence growing demand for services that can
  be applied on multimedia streams
• Continuously diversifying market of end-user
  computation devices
• Sometimes also requested by applications

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Problem Statement

• What is the optimal location to provide/
  implement these multimedia services?
• At sender-side?
• At receiver-side?
• Inside the transportation network, in the
  delivery path between sender and receiver
• Benefits of in-network service provision
• Senders need to transmit only 1 version/ quality
  of a multimedia stream
• Destinations receive (near-)optimal stream

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Our Overlay Network

• Our overlay network consists of interconnected
  proxy servers
• Goals
• Concurrently provide powerful services for a wide
  variety of networked applications
• Extensibility
• This is achieved by combining
• A generic base layer
• A plug-in mechanism which allows deployment of
  application-aware services

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Outline

• Introduction
• Problem Statement
• Our Overlay Network
• Software Architecture
• Example Overlay Services
• Sound Mixer Service
• Face Detection Service
• Performance Evaluation
• Conclusions
• Future Work

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Software Architecture

• Proxy servers run on the GNU/Linux OS
• Implemented as a userspace process
• Uses iptables/netfilter to transfer packets from
  kernel- to userspace and vice versa
• Proxy process consists of 2 subsystems
• Generic base layer
• Application independent
• Plug-in manager through which additional
  functionality can be added to the proxy
• Plug-ins are application-aware
• Each multimedia service is implemented as plug-in

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Software Architecture

• Generic base layer
• Basic user management functionality
• Moves packets between kernel- and userspace
• Plug-in manager
• Enables/manages the installation of plug-ins
• Plug-ins can register interest for certain
  network streams
• Intercepted network packets are handed over to
  the plug-ins which have registered interest
• In the order in which they have registered
  interest
• Checks the packet verdict returned by plug-ins

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Software Architecture
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Sound Mixer Service

• EDM NVE framework
• Supports real-time audio (and video)
  communication between users
• Originally developed for the PC platform
• Sufficient processing power
• PC users receive all audio streams sent out by
  clients currently located in their Area of
  Interest (AoI)
• Recently also ported to mobile devices
• Processing requirements associated with receiving
  and decoding multiple audio streams
  simultaneously and mixing them together locally
  is too high
• Decision to limit number of audio streams a
  mobile client can receive to one

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Sound Mixer Service

• Substantial difference between audio experience
  available to desktop and mobile NVE users
• Sound mixer service bridges this gap
• Maintains separate mixing unit for every client
• Ensures proxy receives necessary input audio
  streams
• Incoming audio packets are decoded and
  subsequently transferred to the correct mixing
  units
• Also considers positional information to generate
  a 3D spatialized output signal

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Sound Mixer Service

• Advantages
• Improves the audio experience provided to mobile
  NVE users
• No additional bandwidth or processing
  requirements are introduced at client-side
• Drawback
• Sound mixer service introduces a small amount of
  additional delay

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Face Detection Service

• iConnect meeting system
• Goal enable both collocated and geographically
  dispersed participants to meet in an efficient
  manner
• Computer-augmented meeting room containing a
  touch-sensitive digital whiteboard
• Acts as shared workspace (display documents, )
• Each participant is represented as an avatar
• Remotely connecting to iConnect also possible
• Shared workspace is displayed on the remote
  screen
• Same collaboration possibilities
• Audio and video conferencing support

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Face Detection Service

• Video conferencing streams of remote participants
  need to be displayed on whiteboard
• Can consume a lot of screen space!
• Face detection service
• Intercepts video conferencing streams
• Decodes these streams and applies face detection
• Result is encoded at much lower resolution and
  framerate and transmitted to the shared
  whiteboard as video avatar

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Face Detection Service

• Need for displaying video stream of remote users
  is eliminated in many cases
• Feedback provided by video avatars suffices to
  guarantee meeting effectiveness
• Saves screen space on the shared whiteboard
• Scarce resource!
• Freed up screen space can be used to display
  other content

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Performance Evaluation

• Performance of the 2 overlay services was tested
  on a single proxy server
• Intel Pentium D 3 Ghz
• Linux kernel 2.6.14
• Simultaneous use of services introduces nearly no
  overhead!

Average CPU Utilization Maximum CPU Utilization
Sound Mixer Service 1,5 4
Face Detection Service 7,5 20
Both services simultaneously 9,5 22
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Conclusions

• I have presented our overlay network consisting
  of interconnected proxy servers
• Generic base layer
• Plug-in mechanism enables installation of
  application-aware services
• Overlay network can provide powerful and
  efficient services for a wide variety of
  networked applications
• ?Need for deploying and managing a separate
  overlay network for each distinct networked
  application is eliminated
• Is confirmed by the experimental results produced
  by the two presented overlay services

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Future Work

• Improve the efficiency of the face detection
  service
• Implementation of an overlay routing plug-in
• Would enable proxy servers to route packets
  around failing or congested network links
• Proxy-to-proxy communication would become more
  resilient to network errors
• Beneficial for end-user
• Continue integration in iConnect system

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Questions?