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DASH in Twitch:Adaptive BitrateStreaming in Live GameStreaming PlatformsKarine Pires, Gwendal SimonTelecom Bretagne, FranceNov 2014
Live Streaming : A New ContextCloud Delivery Process
more and morenon-professionalbroadcasters
2 / 19 K. Pires, G. Simon DASH in Twitch
Live Streaming : A New ContextCloud Delivery Process
CDNmore and moreheterogeneousend-viewers
2 / 19 K. Pires, G. Simon DASH in Twitch
Live Streaming : A New ContextCloud Delivery Process
CDN
Data-Center
2 / 19 K. Pires, G. Simon DASH in Twitch
Live Streaming : A New ContextCloud Delivery Process
CDN
Data-Center
Adaptive Streaming1 video stream = k representations
2 / 19 K. Pires, G. Simon DASH in Twitch
Live Streaming : A New ContextCloud Delivery Process
CDN
Data-Center
+55 millions unique visitors
4th in US internet traffic
2 / 19 K. Pires, G. Simon DASH in Twitch
Two options for the delivery process
Traditional Process
RawVideo
IngestServers
DeliveryServers
3 / 19 K. Pires, G. Simon DASH in Twitch
Two options for the delivery process
Traditional Process
RawVideo
IngestServers
DeliveryServers
Transcoding Process
RawVideo
IngestServers
TranscodeServers
DeliveryServers
3 / 19 K. Pires, G. Simon DASH in Twitch
Which live streams to transcode
TraditionalProcess↓ CPU
↓ QoE
↑ BW
TranscodingProcess↑ CPU
↑ QoE
↓ BW
Trade-off
Live stream ?
4 / 19 K. Pires, G. Simon DASH in Twitch
Our contributions
Adaptive Bit-Rate streaming in Twitch :Real traces from TwitchDecision of which channels should be delivered with ABRComparison of different decision strategies
5 / 19 K. Pires, G. Simon DASH in Twitch
What is a broadcaster
A broadcaster streaming two gaming sessions
online online
nb. of viewers
timet1 t ′
1 t2 t ′2
session 1 session 2
7 / 19 K. Pires, G. Simon DASH in Twitch
Data retrieval
For 3 months → from 6 Jan. to 6 Apr.
time
allchannelsof one
snapshot
9 :00 9 :05 9 :10 9 :15 9 :20every five minutes → one snapshot
Dataset available : http ://dash.ipv6.enstb.fr/dataset/twitch/8 / 19 K. Pires, G. Simon DASH in Twitch
How many online broadcasters
0 10 20 30 40 50 60 70 80 900
2K
4K
6K
8K
10K
Days
Nb.
ofon
line
chan
nels
min max
9 / 19 K. Pires, G. Simon DASH in Twitch
How much bandwidth is needed
0 10 20 30 40 50 60 70 80 900
1
2
Days
Ban
dwid
th(T
bps)
min max
10 / 19 K. Pires, G. Simon DASH in Twitch
Raw videos properties
240p 360p 480p 720p 1080p0
0.2
0.4
0.6
Representation
Sess
ions
ratio
11 / 19 K. Pires, G. Simon DASH in Twitch
Raw videos properties
240p 360p 480p 720p 1080p0
0.2
0.4
0.6
Representation
Sess
ions
ratio
0.1 1 2 100
0.2
0.4
0.6
0.8
1
Video bit-rate (Mbps)CD
Fof
the
sess
ions
480p
11 / 19 K. Pires, G. Simon DASH in Twitch
Raw videos properties
240p 360p 480p 720p 1080p0
0.2
0.4
0.6
Representation
Sess
ions
ratio
0.1 1 2 100
0.2
0.4
0.6
0.8
1
Video bit-rate (Mbps)CD
Fof
the
sess
ions
480p 720p 1080p
11 / 19 K. Pires, G. Simon DASH in Twitch
When to decide a stream should be transcoded
At-startupStrategy
transcoding decision
timet1 t ′
1
On-the-flyStrategy
timet1 t ′
1
transcoding decision
transcoding traditional
13 / 19 K. Pires, G. Simon DASH in Twitch
Strategies
None : no ABRAll : all streams are streamed with ABR
Top-50 (at-startup) : streams that were popularThreshold-1000 (on-the-fly) immediate popularity
14 / 19 K. Pires, G. Simon DASH in Twitch
Strategies
None : no ABRAll : all streams are streamed with ABRTop-50 (at-startup) : streams that were popular
Threshold-1000 (on-the-fly) immediate popularity
14 / 19 K. Pires, G. Simon DASH in Twitch
Strategies
None : no ABRAll : all streams are streamed with ABRTop-50 (at-startup) : streams that were popularThreshold-1000 (on-the-fly) immediate popularity
14 / 19 K. Pires, G. Simon DASH in Twitch
Evaluation settings
Sessions → Twitch datasetViewers → DASH datasetABR → proportional to raw video
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Results : degraded viewers served
0 10 20
0
0.5
1
None
All
Days
Vie
wer
sra
tioTop Threshold
16 / 19 K. Pires, G. Simon DASH in Twitch
Results : costs evaluation
None All ThresholdTop0
50
100
150
-40%-39%
+5%
Strategies
Tota
lPric
e($
M)Delivery Transcode
17 / 19 K. Pires, G. Simon DASH in Twitch
Discussions
preliminary work=global picture→details neglectedmore formal and accurate formulationmore precise QoE estimationbetter transcoding needs modelmanagement of different hardware resources
more efficient strategies can be designedsophisticated strategiesstatistical approaches for popularity forecasting
19 / 19 K. Pires, G. Simon DASH in Twitch
Discussions
preliminary work=global picture→details neglectedmore formal and accurate formulationmore precise QoE estimationbetter transcoding needs modelmanagement of different hardware resources
more efficient strategies can be designedsophisticated strategiesstatistical approaches for popularity forecasting
19 / 19 K. Pires, G. Simon DASH in Twitch