1 RealVideo Network Characteristics Outline RTSP Introduction - - PDF document

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1 RealVideo Network Characteristics Outline RTSP Introduction - - PDF document

Sep 19, 2022 261 likes •353 views

The Hungry Wolf - Bandwidth Measurement of the Congestion Requirements for Video Responsiveness of RealPlayer Streaming media growing Streaming Video Over UDP 350,000 hours of online video broadcast 01 Voice is 32-64 Kbps, but

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SLIDE 1

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Measurement of the Congestion Responsiveness of RealPlayer Streaming Video Over UDP

Jae Chung, Mark Claypool, Yali Zhu

(Technical Report WPI-CS-TR-02-17) Proceedings of the Packet Video Workshop Nantes, France April 2003

http://www.cs.wpi.edu/~claypool/papers/h2h/

The Hungry Wolf - Bandwidth Requirements for Video

  • Streaming media growing

– 350,000 hours of online video broadcast ’01

  • Voice is 32-64 Kbps, but video has range of

data rates

– Videoconference 0.1 Mbps (H.261, MPEG-4) – VCR 1.2 Mbps (MPEG-1) – Broadcast quality 2-4 Mbps (MPEG-2) – HDTV quality 25-34 Mbps (MPEG-2) Thus, potential for more than network capacity

The Wolf on the Prowl – Transport Protocols for Video

  • Streaming video doesn’t like TCP

– Wants rate-based not window-based – Can tolerate some loss – AIMD causes rate fluctuations So, use UDP where application controls

  • But UDP has no congestion control

– Unfair, unfriendly, and even collapse!

  • Approaches to have router catch

– Model video as CBR “firehose” (is it?)

The Wolf Pack – Commercial Video

  • Commercial products have major impact
  • Have been studies characterizing

commercial traffic

– Bandwidth use, frame rate, user use…

  • But no work measuring responsiveness, or

lack of it, of commercial video products

0.2 0.4 0.6 0.8 1 10 20 30 Frame Rate (fps) Cummulative Density TCP UDP

Specific Motivation

TCP UDP

Outline

  • Introduction

√

  • Background

←

  • Experiments
  • Results
  • Analysis
  • Conclusions
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SLIDE 2

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RealVideo Network Characteristics

  • SureStream

– Allows bandwidth scaling

  • Buffering

– Remove jitter

Server RTSP Data: TCP or UDP

  • Choice, unclear
  • We’ll force

Outline

  • Introduction

√

  • Background

√

  • Experiments

←

  • Results
  • Analysis
  • Conclusions

Methodology

  • Select Real Video Clips
  • Construct environment for measuring

congestion response

  • Construct environment to measure ability

to scale (SureStream)

  • Iteratively plan clips varying network

RealVideo Clip Playlist

  • If put in controlled environment, may not

be representative of clips “in the wild”

  • Select large number through search

engines (Yahoo, Google …)

  • Randomly choose 100 (79 analyzed)
  • Geography results:

– 76 US, 9 Canada, 8 UK, 6 Italy, 1 Germany – North American dominance likely reflected in typical user locality of reference

  • Length results:

– Median 3 minutes, min 20 seconds, max 30 minutes

Responsiveness Measurement Environment

  • PIII 700 Mhz, 128 MB RAM, Linux 2.4
  • RealPlayer version 8.0.3
  • Sniffing via tcpdump
  • Loss and round-trip time via ping
  • TBF to limit bandwidth
  • 2 Measurements for each clip
  • (Note, RealTracer for MediaScaling)

Internet Client Hub Router

10Mbps DSL 700Kbps

Client Token Bucket Filter

UDP TCP

Server

Outline

  • Introduction

√

  • Background

√

  • Experiments

√

  • Results

←

  • Analysis
  • Conclusions
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SLIDE 3

3

Distribution of Loss

0.2 0.4 0.6 0.8 1 0.05 0.1 0.15 0.2 Cumulative Density Loss (fraction) 075 Kbps 150 Kbps 300 Kbps 600 Kbps

Distribution of Latency

0.2 0.4 0.6 0.8 1 100 200 300 400 500 600 700 800 900 Cumulative Density RTT (milliseconds) 075 Kbps 150 Kbps 300 Kbps 600 Kbps

Distribution of Packet Sizes

0.2 0.4 0.6 0.8 1 200 400 600 800 1000 1200 1400 1600 Cumulative Density Packet Size (Kbytes) TCP UDP

Outline

  • Introduction

√

  • Background

√

  • Experiments

√

  • Results

√

  • Analysis

– Head to Head

←

– Bandwidth – Scaling – Buffering – Smooth

  • Conclusions

RealPlayer = FairPlayer?

50 100 150 200 250 300 350 400 50 100 150 200 250 Throughput (Kbps) Playout + Buffering Time (Seconds) Clip-19 TCP (DSL: BW = 600Kbps, Q = 10Kbytes) Clip-19 UDP (DSL: BW = 600Kbps, Q = 10Kbytes)

RealPlayer = FoulPlayer?

100 200 300 400 500 600 50 100 150 200 250 Throughput (Kbps) Playout + Buffering Time (Seconds) Clip-31 TCP (DSL: BW = 600Kbps, Q = 10Kbytes) Clip-31 UDP (DSL: BW = 600Kbps, Q = 10Kbytes)

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SLIDE 4

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Bandwidth Distribution

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 10 20 30 40 50 60 70 Cumulative Density Average Bandwidth for 75 Kbps (Kbps) Average Bandwidth for TCP Average Bandwidth for UDP 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 20 40 60 80 100 120 140 Cumulative Density Average Bandwidth for 150 Kbps (Kbps) Average Bandwidth for TCP Average Bandwidth for UDP 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 50 100 150 200 250 300 Cumulative Density Average Bandwidth for 300 Kbps (Kbps) Average Bandwidth for TCP Average Bandwidth for UDP 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 100 200 300 400 500 600 Cumulative Density Average Bandwidth for 600 Kbps (Kbps) Average Bandwidth for TCP Average Bandwidth for UDP

600 Kbps 300 Kbps 150 Kbps 75 Kbps

Head-to-Head Bandwidth

50 100 150 200 250 300 350 400 50 100 150 200 250 300 350 400 Average Bandwidth for UDP (Kbps) Average Bandwidth for TCP (Kbps) 75 Kbps 150 Kbps 300 Kbps 600 Kbps

Bandwidth Difference Distribution

0.2 0.4 0.6 0.8 1

  • 1
  • 0.8
  • 0.6
  • 0.4
  • 0.2

0.2 0.4 0.6 0.8 Cumulative Density Normalized Average Bandwidth Difference (TCP-UDP) 75 Kbps 150 Kbps 300 Kbps 600 Kbps

Mostly TCP-Friendy!

  • Remove low bandwidth (36%)
  • Then remove unscalable (14%)

Outline

  • Introduction

√

  • Background

√

  • Experiments

√

  • Results

√

  • Analysis

– Head to Head

√

– Bandwidth

√

– Scaling

←

– Buffering – Smooth

  • Conclusions

Media Scaling Distribution

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 2 3 4 5 6 7 8 9 Cumulative Density Number of Scales (Coded-Bandwidth)

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SLIDE 5

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Media Scales Media Scaling Dynamics (1)

50000 100000 150000 200000 250000 50 100 150 200 250 300 350 Coded-Bandwidth (bps) Playout + Buffereing Time (sec) local bw limit (35 kbps) Scale (Coded-BW) Movement for Clip-65 TCP Scale (Coded-BW) Movement for Clip-65 UDP

Media Scaling Dynamics (2)

50000 100000 150000 200000 250000 300000 20 40 60 80 100 120 140 Coded-Bandwidth (bps) Playout + Buffereing Time (sec) local bw limit (35 kbps) Scale (Coded-BW) Movement for Clip-78 TCP Scale (Coded-BW) Movement for Clip-78 UDP

Media Scaling Distributions

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 2 4 6 8 10 Cumulative Density Number of Scale (Coded-Bandwidth) Changes Number of Scale Changes Seen for TCP Number of Scale Changes Seen for UDP

Media Scaling Adaptation Speed

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 10 20 30 40 50 60 70 80 Cumulative Density Elaps Time in Seconds: 0 to time(Coded-BW < 35kbps) Scale Adaptation Speed for TCP Scale Adaptation Speed for UDP

Outline

  • Introduction

√

  • Background

√

  • Experiments

√

  • Results

√

  • Analysis

– Head to Head

√

– Bandwidth

√

– Scaling

√

– Buffering

←

– Smooth

  • Conclusions
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SLIDE 6

6

Buffering Rate to Playout Rate

1 2 3 4 5 6 7 50 100 150 200 250 300 350 400 Average Buffering Rate / Average Steady Playout Rate Average Steady Playout Rate (Kbps) TCP (All DSL-TBF Runs) UDP (All DSL-TBF Runs)

Buffering Rate to Playout Rate Distribution

0.2 0.4 0.6 0.8 1 1 2 3 4 5 6 7 Cumulative Density Average Buffering Rate / Average Steady Playout Rate TCP (All LAN Runs) UDP (All LAN Runs)

Smoothness

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1/2 1 2 Cumulative Density Throughput Ratio TCP UDP

Smoothness at each Bottleneck

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1/2 1 2 Cumulative Density Throughput Ratio for 75 Kbps TCP UDP 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1/2 1 2 Cumulative Density Throughput Ratio for 150 Kbps TCP UDP 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1/2 1 2 Cumulative Density Throughput Ratio for 600 Kbps TCP UDP 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1/2 1 2 Cumulative Density Throughput Ratio for 300 Kbps TCP UDP

Discussion of Results

  • No concrete incentives to respond to

congestion

– In fact, may be “rewarded” for not

  • However, clearly responds

– often TCP-Friendly

  • Content providers need to provide chance

for scalability

  • But buffering at higher rate is bad for

network

  • TCP can be as smooth as UDP
  • So why not TCP? API is limiting

Conclusions

  • Response to congestion important to

Internet

  • Measured responsiveness of RealVideo
  • RealVideo over UDP is largely responsive

– receives typically same bandwidth as TCP – often TCP friendly

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SLIDE 7

7

Future Work? Future Work

  • Other commercial Players

– Microsoft Media Player

  • Live clips (versus pre-recorded clips)
  • Perceptual quality of video over TCP versus

UDP

  • Characterization of clips on Internet

– So can examine “typical” clips