On Design of Adaptive Internet Streaming Applications:An Architectural Perspective

Reza RejaieAT&T Labs – ResearchMenlo Park, California

Contributions• An E2E architecture that integrates CC, EC and QA in a coherent fashion.

• Limitations of any E2E architecture.

• A proxy-based extended architecture for playback streaming applications.

•A simple design methodology for unicast and non-interactive streaming applications.

Main Components1. Congestion Control(CC) module

adjusts transmission rate.

• Network-friendly => TCP-friendly, e.g. RAP, TFRC, LDA, …

2. Error Control (EC) module recovers from high priority losses selectively.

3. Quality Adaptation (QA) module matches the quality with available BW.

• Layered encoding.

End-to-End Architecture• Buffering at both ends is used to absorb short-lived changes in BW.

• Long-term changes in BW triggers QA.

• EC & QA should properly share the BW.

• QA determines 1) number of active layers and 2) allocated BW to each layer.

+

bw (t)2

bw (t)1

bw (t)0

Inte

rnetBW(t) BW(t)

Lay

ered

Enc

ode r

Sou

rce

Con

gest

ion

Con

trol

Dis

play

buf2

buf1

buf0

Ack

er

buf2

buf1

buf0

Dec

oder

bw (t)0

bw (t)1

bw (t)2

Available BW Quality Adaptation

ServerBuffer

ClientBuffer

BW BW

AckAck

Application Specific Application SpecificNetwork Specific

Motivation• Internet requires all applications to perform end-to-end congestion control

• Streaming Applications require iso-chronous processing & QoS.

• Lack of high level architecture that properly integrates congestion control.

• Target applications: Unicast & non-interactive Internet streaming applications

Internet Streaming applications should be quality adaptive.

Multimedia Proxy Caching• Multimedia proxy caching(MC) is suited only for playback streaming applications

•Cache popular streams with “appropriate” quality at a proxy close to interested clients.

• Adjust the quality of a cached stream based on clients’ BW and stream’s popularity.

• Layered encoding allows fine-grained replacement and fine-grained prefetching.

Fine-grained adjustment in quality of cached streams.

• MC achieves scalability, higher delivered quality and higher level of interactivity.

• Existing Web caches are unable to perform multimedia proxy caching efficiently.

For More Information• http://www.research.att.com/~reza