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Video Multicast over the Internet. Bell Lab. And Georgia Institute of Technologies IEEE Network · March/April 1999. Presented by: Liang-Yuh Wu Lung-Yuan Wu Hao-Hsiang Ku. 12 / 6 / 2001. Agenda. 1. Abstract 2. Basic idea 3. Single-stream video multicast

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Video Multicast over the Internet

Bell Lab. And Georgia Institute of Technologies

IEEE Network · March/April 1999

Presented by: Liang-Yuh Wu

Lung-Yuan Wu

Hao-Hsiang Ku

12 / 6 / 2001


1. Abstract

2. Basic idea

3. Single-stream video multicast

4. Replicated-stream video multicast

5. Layered video multicast

6. Replicated vs. Layered

7. Error Control

8. Concluding Remarks



  • Multicast of video / future network service

    Video Conference

    Distance Learning

    Remote Presentation

    Media-on-Demand ( MOD,VOD )

  • Lacks support for QoS assurance

  • Heterogeneity of the Internet transmission

 Problem of “ Real time & Bandwidth”

Focus & Discussion ??

Base requires for Multicast video :

  • Mechanisms for Multicast data delivery

  • Ability to accommodate Real-time video

    Focus on:

  • 1.How real-time video can be accommodated

    over Internet


Some general approaches and issue


---Delay jitter, Data loss

1. Using QoS reserve resources

2. Using adaptive rate control “ Feedback

mechanism ”


4.Change compression parameters

5.Error control technology

Basic idea

  • Video Bit-Rate adaptation

  • Adaptive Bit-Rate Video Multicast Options

    1. Single Stream Adaptive Approach

    2. Replicated Adaptive Streams Approach

    3. Layered Video Streams Approach

Single stream video multicast
Single-stream Video Multicast

  • The IVS Approach (in the H.261 encoder)

  • Feedback information is based on packet loss measured at the receiver

  • Packet loss is detected using RTP (Real-time Transport Control)

  • RTP sends “reception reports” that provide feedback information

Single stream video multicast cont
Single-stream Video Multicast(cont.)

  • Feedback implosion problem

    • Probabilistic multicast technique

    • Probing mechanism

  • Can’t provide fair treatment to multiple receiver in a heterogeneous environment

  • Tradeoff between multicast and unicast

Replicated stream video multicast
Replicated-Stream Video Multicast

  • The DSG (Destination Set Grouping) Protocol

  • The goal of the DSG:

    • To improve fairness over a single-group feedback-controlled video multicast

    • To address “scalability”

  • By transmitting video of differing quality and differing data rate on different multicast channels and allowing receivers to select the most appropriate one.

Replicated stream video multicast cont
Replicated-Stream Video Multicast(cont.)

  • The DSG protocol has two main Components:

    • Intra-stream protocol

    • Inter-stream change protocol

  • A DSG experiment result :

    • Fairness among receiver is improved significantly over a single-group approach while incurring only a small additional bandwidth overhead.

Layered video multicast
Layered Video Multicast

  • Video layering can be supported by many video compression techniques

    • EX: MPEG-2 supports layered encoding by defining four scalable modes

  • Layered Video Multicast Protocol

    • Receiver-driven Layered Multicast (RLM)

    • Hierarchical Rate control (HRC)

Receiver driven layered multicast
Receiver-driven Layered Multicast

  • Receiver-based control

    • Advantage:

      • burden of adaptation is moved from the sender to the receiver

  • Join-experiment

    • result is successful

    • result is failed

Receiver driven layered multicast cont
Receiver-driven Layered Multicast(cont.)

  • The key to scalability in layered multicast is “adding or dropping a layer”

  • Shared Learning

    • Advantage:

    • Disadvantage:

      • unnecessary bandwidth and message processing overhead

      • Too much state information

Hierarchical rate control hrc
Hierarchical Rate control (HRC)

  • Layered Video Multicast with retransmissions (LVMR)

    • two key contributions:

      • retransmitting lost packets

      • adapting to network congestion and heterogeneity using HRC

  • Hierarchical Rate control (HRC)

    • to distribute the information between the sender, receivers, and some agents

    • each entity maintains only the information relevant to itself

Hierarchical rate control hrc cont
Hierarchical Rate control (HRC)(cont.)

  • Comparing with RLM:

    • allow receiver to maintain minimal state information

    • decrease control traffic on the multicast session

    • multiple experiments to be conducted simultaneously

    • drop the correct layer(s) during congestion in most case

Hierarchical rate control hrc cont1
Hierarchical Rate control (HRC)(cont.)

  • In addition to avoid the above drawback of RLM

    • Comprehensive group knowledge base

    • Collaborative layer drop

      • decrease layer oscillation

      • achieves more effective rate adaptation

      • maintains better video reception quality

    • Add-layer experiment

      • decrease unnecessary add-layer experiment

      • provide smoother video quality

Replicated stream vs layered video
Replicated-stream VS. Layered video

  • For video multicast, layering is determined more by the coding requirements than by the bandwidth requirements

  • Replicated-stream VS Layered video:

    • bandwidth economy

    • Processing overhead

Error control
Error Control

1.Layered Video Multicast with Retransmission (LVMR)

2.Structure-Oriented Resilient Multicast (STORM)

3.Client-Server Architecture

The key idea in lvmr
The Key Idea In LVMR

  • Use a statically configured logical tree

  • Set Designated Receivers (DRs) at each level

  • Improve efficiency by no asking for retransmission

  • Improve response time by sending immediate message and multicast retransmissions

  • Use Buffers

  • Combine retransmission mechanisms

The key idea in strom
The Key Idea In STROM

  • Each receiver to dynamically select the best possible DR

  • Use a dynamically logical tree

  • Receiver decide the latency or reliability

The steps of storm
The Steps of STORM

  • 1.Build the recovery structure

  • 2.Selection of Parent Nodes

  • 3.Adapting the structure

The key idea in client server architecture
The Key Idea In Client-Server Architecture

  • Separate the actual senders and receivers.

  • Receiver either get the original or repaired video stream.

  • The retransmit server and the repair server can be organized into LVMR

  • Using RTP

  • Repair Buffer

Concluding remarks
Concluding Remarks

  • Network congestion lead to degrade the video quality.

  • Non-adaptive streams of video data don not share resource well in a best-effort network.

Future work
Future Work

  • To build a mechanisms which provide for the co-existence and resource sharing of video multicast stream .

  • Formalization of the notion of fairness

  • Understanding the effect of pricing on the behavior of receiver in a multicast video environment.

The End

Thank you so much!!