1. DYNAMIC ADAPTIVE STREAMING OVER
HTTP/2.0
Christopher Mueller, Stefan Lederer, Christian Timmerer and Hermann Hellwagner
Alpen-Adria Universität Klagenfurt (AAU)  Faculty of Technical Sciences (TEWI)
Institute of Information Technology (ITEC)  Multimedia Communication (MMC)
17-07-2013
Christopher Mueller 1Dynamic Adaptive Streaming over HTTP/2.0

2. OUTLINE
 Motivation & Contribution
 Introduction
 Dynamic Adaptive Streaming over HTTP (DASH)
 HTTP/2.0
 Experimental Setup & Evaluation
 Overhead
 Link Utilization
 Behavior under gradual changing bandwidth conditions
 Conclusion
Christopher Mueller 2Dynamic Adaptive Streaming over HTTP/2.0

3. MOTIVATION & CONTRIBUTION
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 Situation in today's networks and new technologies
 Real-time entertainment is currently accounting for more than 50% of
the whole Internet traffic
 HTTP is one of the major protocols used to deploy a variety of services
 HTTP/2.0 standardization has recently started and SPDY has been
chosen as working draft
 DASH has the potential to play a significant role in future networks
Optimizations and problem analysis’s are crucial at that early stage of
standardization and deployment of DASH and HTTP/2.0
 Contribution
 First implementation and integration of MPEG-DASH with HTTP/2.0
 Evaluation of MPEG-DASH with different HTTP protocol versions with
network conditions that are common for fixed and wireless networks

4. DYNAMIC ADAPTIVE STREAMING
OVER HTTP – IN A NUTSHELL
 Dynamic adaptation to the network conditions
 Reuse of existing Internet infrastructure
 Logic is located at the client side
 Flexible and scalable deployment
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Multiple Quality Levels Varying Bandwidth Conditions
Selects the appropriate
segments for each
timepoint

5. HTTP/2.0 - SPDY
 HTTP Problems
 HTTP/1.0 uses one TCP connection per request and no pipelining support
 HTTP/1.1 solves problems of HTTP/1.0, but unfortunately not many
proxies are supporting it due to the Head of Line blocking problem
 Recently the IETF has started the development of HTTP/2.0
 SPDY has been officially chosen as working draft
 The protocol is based on TCP and maintains a single connection for each
session
 Multiple streams can be multiplexed on this connection
 SPDY is fully compatible with HTTP and could be integrated as a session layer
between HTTP and TCP
The network communication is based on frames that are exchanged between
client and server
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6. EVALUATION SETUP
 Evaluation of MPEG-DASH with different HTTP protocol versions
 Conditions that are common for fixed and mobile access networks
 Overhead
 Link Utilization
 Switching behavior under gradual changing bandwidth conditions
 For our evaluation of the different HTTP versions we have
consistently used the same settings
 Server: Apache with mod_spdy, modified to enable non encrypted
communication
 Network: Linux traffic control (tc) and netem
 Client: MPEG-DASH VLC Plugin, spdylay
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Stays the same over all experiments
Same content for all experiments

7. OVERHEAD EVALUATION
 Overhead is equal for all versions and quite small, i.e., 5 to 7
% for 2 second segments and media bitrates higher than 700
kbps
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8. LINK UTILIZATION
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 Link utilization with different quality levels, RTT’s and
available bandwidths
➪ Bad performance of HTTP 1.0 due to TCP slow start

9. GRADUAL CHANGING BANDWIDTH
CONDITIONS
 SPDY and HTTP/1.1 outperform HTTP/1.0 and stay constant
over RTTs ranging from 0 to 150ms
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10. CONCLUSION
 First implementation and evaluation of MPEG-DASH with
HTTP/2.0 (SPDY)
 Evaluation of MPEG-DASH with different HTTP protocol
versions under various conditions
 Overhead is equal for all versions and quite small, i.e., 5 to 7 % for
2 second segments and media bitrates higher than 700 kbps
 HTTP/1.0 achieves link utilization equal or higher than 90 % for
RTTs ranging from 0 to 50ms but in case of RTTs between 100 and
150 ms only 75 to 85 % can be utilized
 HTTP/1.1 and SPDY performs constant over varying RTTs due to
the persistent connection and pipelining features
SPDY performs equally well as HTTP/1.1 but SPDY offers
the HTTP/1.1 functionalities implicitly
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11. THANK YOU FOR YOUR ATTENTION
… questions, comments, etc. are welcome …
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Christopher Mueller | dash.itec.aau.at
Alpen-Adria Universität Klagenfurt (AAU)  Faculty of Technical Sciences (TEWI)
Institute of Information Technology (ITEC)  Multimedia Communication (MMC)

12. BACKUP
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13. THE SPDY PROTOCOL
The protocol is based on TCP and maintains a single
connection for each session
 Multiple streams can be multiplexed on this connection
 SPDY is fully compatible with HTTP and could be integrated
as a session layer between HTTP and TCP
The network communication is based on frames that are
exchanged between client and server
 Only two frame types that can be distinguished on the first bit
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14. LINK UTILIZATION AND SSL
 SSL encryption does not significantly influence link utilization but
it introduces additional complexity on the server and the client
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