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A Quest for an Internet VideoQuality-of-Experience Metric

Athula Balachandran, Vyas Sekar,Aditya Akella, Srinivasan Seshan,

Ion Stoica, Hui Zhang

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Internet Video is taking off

Improve Users’ Quality of Experience

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Video Quality Metrics: The State of the Art

Objective Score (e.g., Peak Signal to Noise Ratio)

Subjective Scores(e.g., Mean Opinion

Score)

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Problem 1: New Effects, New Metrics

PLAYERSTATES

EVENTS

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Problem 1: New Effects, New Metrics

PLAYERSTATES

EVENTS

Joining Playing Buffering Playing

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Bufferempty

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Switchbitrate

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Problem 1: New Effects, New Metrics

PLAYERSTATES

EVENTS

Joining Playing Buffering Playing

Bufferfilled up

Bufferempty

Bufferfilled up

Switchbitrate

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Problem 1: New Effects, New Metrics

PLAYERSTATES

EVENTS

Joining Playing Buffering Playing

Bufferfilled up

Bufferempty

Bufferfilled up

Switchbitrate

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Problem 1: New Effects, New Metrics

PLAYERSTATES

EVENTS

Joining Playing Buffering Playing

Bufferfilled up

Bufferempty

Bufferfilled up

Switchbitrate

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Problem 1: New Effects, New Metrics

PLAYERSTATES

EVENTS

Joining Playing Buffering Playing

Bufferfilled up

Bufferempty

Bufferfilled up

Switchbitrate

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Problem 1: New Effects, New Metrics

PLAYERSTATES

EVENTS

Joining Playing Buffering Playing

Bufferfilled up

Bufferempty

Bufferfilled up

Switchbitrate

Join Time Buffering RatioRate of buffering

Rate of switchingAverage bitrate

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Problem 2: Opinion Scores Engagement

Opinion Scores- Not representative of “in the wild”

experience- Combinatorial explosion of parameters

Engagement as replacement for opinion score. (e.g., Play time, customer return rate)

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Internet Video QoE

Objective ScoresPSNR

Subjective ScoresMOS

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Internet Video QoE

Objective ScoresPSNR

Subjective ScoresMOS

Engagement(e.g., Fraction of video viewed)

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Internet Video QoE

Objective ScoresPSNR

Join Time, Avg. bitrate, …?

Subjective ScoresMOS

Engagement(e.g., Fraction of video viewed)

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Internet Video QoE

Objective ScoresPSNR

Join Time, Avg. bitrate, …?f(Join Time, Avg. bitrate, …)

Subjective ScoresMOS

Engagement(e.g., Fraction of video viewed)

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Internet Video QoE

Objective ScoresPSNR

Join Time, Avg. bitrate, …?f(Join Time, Avg. bitrate, …)

Subjective ScoresMOS

Engagement(e.g., Fraction of video viewed)

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Outline

• Need for a unified QoE

• What makes this hard?

• Our proposed approach

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Challenge: Complex Engagement-to-metric Relationships

Enga

gem

ent

Quality Metric

[Dobrian et al. Sigcomm 2011] 19

Challenge: Complex Engagement-to-metric Relationships

Enga

gem

ent

Quality Metric

Non-monotonic

E

ngag

emen

t

Average bitrate

[Dobrian et al. Sigcomm 2011] 20

Challenge: Complex Engagement-to-metric Relationships

Enga

gem

ent

Quality Metric

Non-monotonic

E

ngag

emen

t

Average bitrate

En

gage

men

t

Rate of switching

Threshold

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Challenge: Complex Metric Interdependencies

Join Time Bitrate

Rate of buffering

Rate of switching

Buffering Ratio

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Challenge: Complex Metric Interdependencies

Join Time Bitrate

Rate of buffering

Rate of switching

Buffering Ratio

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Challenge: Complex Metric Interdependencies

Join Time

Rate of buffering

Rate of switching

Buffering Ratio

Bitrate

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Challenge: Complex Metric Interdependencies

Join Time Avg. bitrate

Rate of buffering

Rate of switching

Buffering Ratio

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Need to learn these complex engagement-to-metric relationships and metric-to-metric dependencies

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Casting as a Learning Problem

MACHINE LEARNING

Engagement Quality Metrics

QoE Model

Need to learn these complex engagement-to-metric relationships and metric-to-metric dependencies

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Impact of the ML algorithm• Classify engagement into uniform classes• Accuracy = # of accurate predictions/ # of cases

ML algorithm must be expressive enough to handle the complex relationships and interdependencies

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Challenge: Confounding Factors

Live and VOD sessions experience similar quality

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Challenge: Confounding Factors

However, user viewing behavior is very different

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Challenge: Confounding Factors

Devices User InterestConnectivity

Need systematic approach to identify and handle confounding factors

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Domain-specific Refinement

MACHINE LEARNING

Engagement Quality Metrics

QoE Model

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Domain-specific Refinement

MACHINE LEARNING

Engagement Quality Metrics

QoE Model

Confounding Factors

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Improved prediction accuracy

Refined ML models can handle confounding factors

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Concluding Remarks• Internet Video needs unified quantitative QoE

• What makes this hard?– Complex engagement-to-metric relationships– Complex metric-to-metric interdependencies– Confounding factors (e.g., genre, device)

• Promising start– Machine learning + domain-specific refinements

• Open Challenges– Coverage over confounding factors– System Design