P2P streaming today uses constant bitrate video, primarily because it is easier to cut such video into fixed-throughput substreams and deliver it via multiple peers. This approach suffers from low reliability of end-to-end throughput which can cause playback freezes. It also suffers from extreme variation in throughput across peers. This paper proposes a variable-bitrate method for P2P streaming which solves these problems. The proposed method is designed for scalability as well as spontaneous network organization because of its low demand on resources.
A Method for Extremely Scalable and Low Demand Live P2P Streaming based on Variable Bitrate
1.
2. .
.
P2P Streaming: Models and Problems
M.Zhanikeev -- maratishe@gmail.com --
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3. .
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P2P Streaming Models
1.
◦ many software products
-- all based on default
BitTorrent
…
Share
BitTorrent model 11 ,
aka the pull paradigm
2.
Content
Provider
(origin)
P2P Network
substream model 10 ,
aka the push paradigm
◦ several existing services
07 08 09
◦ not limited to P2P
networks, also work in
clouds 03
03 myself+0 "Multi-Source Stream Aggregation in the Cloud" Wiley Book on Advanced Content Delivery ... Clouds (2013)
08 K.Park+4 "An Analysis of User Dynamics in P2P Live Streaming Services" ICC (2010)
09 C.Wu+2 "Diagnosing Network-wide P2P Live Streaming Inefficiencies" IEEE INFOCOM (2009)
10 Z.Li+4 "Towards Low-Redundancy Push-Pull P2P Live Streaming" QShine (2008)
11 C.Stais+1 "Realistic Media Streaming over BitTorrent" Future Network and Mobile Summit (2012)
M.Zhanikeev -- maratishe@gmail.com --
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4. .
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P2P Substream Method
….
P2P Connection
shake
hands than
use continuously
• basic idea:
….
….
M.Zhanikeev -- maratishe@gmail.com --
….
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5. .
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Problems and Solutions
•
quality management
1.
2.
•
overhead
1.
2.
•
BitTorrent: RTT per piece
substream: switching time at re-election
optimization
1.
2.
•
BitTorrent: nothing
substream: parent/child re-election
BitTorrent: nothing, but some selection algorithms
substream: multihop optimization is possible -- scheduling and flow problems
the biggest problem: data unit has constant size!
M.Zhanikeev -- maratishe@gmail.com --
Extremely Scalable ... Live P2P Streaming based on Variable Bitrate -- http://tinyurl.com/marat131205 ---
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6. .
.
P2P Streaming: Social Features
M.Zhanikeev -- maratishe@gmail.com --
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7. .
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P2P Streaming: Social Features
Scale
Traffic
flow
•
note: P2P delivery network is not really
a tree
• reality shows that your remote peers are
power-law distributed in throughput
◦ gets harder to find good peers with longer
lists
…
…
…
…
M.Zhanikeev -- maratishe@gmail.com --
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8. .
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Bitrate: CBR, VBR, SVC
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9. .
.
CBR, VBR, SVC
• VBR and SVC are both part of
ITU-T H264 12
VBR: really extreme variation in throughput
• SVC: smoother distribution 13 , with some control over smoothness 14
•
why: SVC is based on hierarchy of layers which can be moved around within GOP
Block
GOP
CBR
Time
Block
GOP
Frame size
Frame size
GOP
Frame size
◦
VBR
Time
Block
SVC
Time
12 "Advanced video coding for generic audiovisual services" ITU-T Recommendation H.264 (2012)
13 R.Kusching+2 "An Evaluation of TCP-based Rate-Control ... Streaming of H.264/SVC" ACM SIGMM MMsys) (2010)
14 M.Fidler+3 -M.Zhanikeev -- maratishe@gmail.com "Efficient Smoothing of Robust VBR ... LiveTraffic ... Slice-Based..." CCNC (2007)
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10. .
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Bitrate Models and Distributions
Frame size (kb)
•
real traces from 15
VBR versus single-layer SVC
SVC
12
12
Frame size (kb)
•
8
4
0
0
20
40
60
80
Time sequence
100
VBR
8
4
0
0
20
40
60
80 100
Distribution sequence
15 P.Seeling+2 "Network Performance Evaluation with Frame Size and Quality Traces ..." IEEE Comm. Surveys... (2004)
M.Zhanikeev -- maratishe@gmail.com --
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11. .
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The Proposal: VBR Subtreams
M.Zhanikeev -- maratishe@gmail.com --
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12. .
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Recap: The Objectives
.
The Main Objective is...
.
... to build a method which can
.
adapt to to any peer distribution in realtime
• VBR is fixed, no control parameter
• SVC can be controlled by switching between encoders
ultimately: raw manipulation by shifting SVC blocks around the GOP
• ideal success: distribution of throughput in peers = distribution of
•
framesize in GOP
M.Zhanikeev -- maratishe@gmail.com --
Extremely Scalable ... Live P2P Streaming based on Variable Bitrate -- http://tinyurl.com/marat131205 ---
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13. .
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Proposal: Substream Design
•
simple:
pick a
frame position in GOP and assign it to one peer
◦ positions: 1st, 2nd, ....
•
expected outcome:
since 1st frame is normally the largest in GOP, that peer
should be able to support high throughput
◦ by extension, most other peers carry much lower load
◦ size of GOP = number of peers, by design
GOP
CBR
Time
M.Zhanikeev -- maratishe@gmail.com --
Block
GOP
Frame size
Block
Frame size
Frame size
GOP
VBR
Time
Block
SVC
Time
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Proposal: Dynamics
Parent A
Client
Bigger frames
(GOP pos x)
Failed to
receive
Re -order
parents
Close
connection
Pick a
better
candidate
Parent B
Bigger frames
(GOP pos x)
Smaller frames
(GOP pos y)
M.Zhanikeev -- maratishe@gmail.com --
traditional substream:
find a new peer for a substream
• proposed: swap frame
positions between two peers
Only for changed
frames/parents/GOP pos
Connection
close detected
•
Periodic
check/update
◦ peers are initially selected
close to the expected
distribution, so no new
peers are necessary
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16. .
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Simulation: Models and Parameters
CBR
SVC
VBR
1
Value
0.8
1. pick VBR I-Frame size as
set it to 1
0.6
2. pick I-Frame size of SVC as a
0.4
3. pick frame size of SBR as a
fraction of 1
fraction of 1
0.2
4. use these fractions as
parameters
0
0
10
M.Zhanikeev -- maratishe@gmail.com --
20
30
Distribution sequence
40
50
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17. .
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Simulation: E2E Throughput Model
drops in throughput
longer paths experience more drops (not deeper!, more in number)
a parameter defines the range of drop probabilities for sampling one's peers
• throughput variation is modeled as
•
•
Throughput
Time slot
100%
Simulation
parameters
parameter
M.Zhanikeev -- maratishe@gmail.com --
0%
Time
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18. .
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Ratio of VBR/CBR and SVC/CBR (freeze time)
Results : Freeze Time
SVC to CBR
VBR to CBR
7
6
x=0.05
5
x=0.2
•
x=1
4
3
simple lesson:
framesize
distributions are good, as long
as they are not extreme
• CBR can outperform VBR/SVC
below frame size of
0.2 -- 1/5th of VBR I-Frame)
only
y=1
2
1
0
0
0.3
M.Zhanikeev -- maratishe@gmail.com --
0.6
0.9
CBR level
1.2
1.5
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19. .
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Throughput gain (higher / lower) (kbps)
Results : Gain (social)
1.9
•
1.7
SVC substream design?
Slow peers
1.5
viewpoint: how much can a
user benefit from a VBR/
• test various peer distributions
and find out
1.3
•
1.1
gain: best SVC/VBR
throughput divided by the
number of CBR
0.9
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Normalized lower throughput
M.Zhanikeev -- maratishe@gmail.com --
0.9
1
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Wrapup
•
VBR/SVC substream design create a socially
adequate method
◦ after all, is it your fault that your 3G shapes your throughput?
• VBR/SVC substream design has to be a
clean slate -- frame position
assignment is proposed
• results show that
is smoother
SVC is preferred because its framesize distribution
◦ even more becuase the distribution can, in theory, be controlled
M.Zhanikeev -- maratishe@gmail.com --
Extremely Scalable ... Live P2P Streaming based on Variable Bitrate -- http://tinyurl.com/marat131205 ---
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21. .
.
That’s all, thank you ...
M.Zhanikeev -- maratishe@gmail.com --
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The PUSH vs PULL Argument
• mathematical argument in
[03]
Client
Server
Client
Server
Pull
M.Zhanikeev -- maratishe@gmail.com --
overhead =
RTT for each piece
• overhead can be overcome
only by drastically
increasing the number of
remote peers --
Push
……
•
……
swarming
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Reference: Average Throughput
Ratio of average throughput (-log(1/y) for y < 1)
SVC/CBR
VBR/CBR
3
1
unit I-Frame size is
50kb
known fact: VBR/SVC can
support the same quality
0.5
at 1/2 of CBR's throughput 15
2.5
•
CBR < VBR
2
VBR < CBR
1.5
•
VBR < 0.5 * CBR
0
• 1/2 of CBR's throughput is at
about 20kb
framesize
-0.5
-1
of CBR
-1.5
0
10
20
30
40
50
CBR Frame Size (kb)
60
70
15 P.Seeling+2 "Network Performance Evaluation with Frame Size and Quality Traces ..." IEEE Comm. Surveys... (2004)
M.Zhanikeev -- maratishe@gmail.com --
Extremely Scalable ... Live P2P Streaming based on Variable Bitrate -- http://tinyurl.com/marat131205 ---
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24. .
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Features: Taxonomy
• is your
data unit regular?
Content
BLOCK
GOP
FRAME
Fixed
Regular
M.Zhanikeev -- maratishe@gmail.com --
adaptive in realtime?
GOP
BLOCK
FRE
and can it be
FIR
Fixed
Irregular
FRAME
Adaptive
Irregular
AIR
This
method
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SVC in P2P: Disclaimer
• SVC is considered for P2P in literature
1. BitTorrent with variable-size pieces 04
2. BitTorrent pieces as multiples of GOP 05
3. optimization for SVC layer repacking in small scale streaming tool called SPPM
(Stanford)
◦ assignment by frame size positions is still the unique contributions
◦ socially, the proposed method will scale while SPPM will not
04 N.Capovilla+4 "...Distributing Scalable Content over P2P Networks" MMEDIA (2010)
05 P.Baccichet+3 "Low-delay Peer-to-Peer Streaming using Scalable Video Coding" Packet Video (2007)
M.Zhanikeev -- maratishe@gmail.com --
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[01] R.Buyya+3 (2008)
Content Delivery Networks
Springer LNEE, vol.9
[03] myself+0 (2013)
Multi-Source Stream Aggregation in the Cloud
Wiley Book on Advanced Content Delivery ... Clouds
[04] N.Capovilla+4 (2010)
...Distributing Scalable Content over P2P Networks
MMEDIA
[05] P.Baccichet+3 (2007)
Low-delay Peer-to-Peer Streaming using Scalable Video Coding
Packet Video
[06] C.Gurler+2 (2012)
Variable chunk size ... and ... window for P2P streaming of scalable video
ICIP
M.Zhanikeev -- maratishe@gmail.com --
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[07] B.Li+5 (2008)
Inside the New Coolstreaming: Principles, Measurements and Performance
Implications
IEEE INFOCOM
[08] K.Park+4 (2010)
An Analysis of User Dynamics in P2P Live Streaming Services
ICC
[09] C.Wu+2 (2009)
Diagnosing Network-wide P2P Live Streaming Inefficiencies
IEEE INFOCOM
[10] Z.Li+4 (2008)
Towards Low-Redundancy Push-Pull P2P Live Streaming
QShine
[11] C.Stais+1 (2012)
Realistic Media Streaming over BitTorrent
Future Network and Mobile Summit
M.Zhanikeev -- maratishe@gmail.com --
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.
[12]
(2012)
Advanced video coding for generic audiovisual services
ITU-T Recommendation H.264
[13] R.Kusching+2 (2010)
An Evaluation of TCP-based Rate-Control ... Streaming of H.264/SVC
ACM SIGMM MMsys)
[14] M.Fidler+3 (2007)
Efficient Smoothing of Robust VBR Video Traffic ... Slice-Based...
CCNC
[15] P.Seeling+2 (2004)
Network Performance Evaluation with Frame Size and Quality Traces ...
IEEE Comm. Surveys...
[16] J.Surowiecki (2004)
The Wisdom of Crowds
Doubleday
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