MPEG Dynamic Adaptive Streaming over HTTP (DASH) is a new streaming standard that has been recently ratified as an international standard (IS). In comparison to other streaming systems, e.g., HTTP progressive download, DASH is able to handle varying bandwidth conditions providing smooth streaming. Furthermore, it enables NAT and Firewall traversal, flexible and scalable deployment as well as reduced infrastructure costs due to the reuse of existing Internet infrastructure components, e.g., proxies, caches, and Content Distribution Networks (CDN). Recently, the Hypertext Transfer Protocol Bis (httpbis) working group of the IETF has officially started the development of HTTP 2.0. Initially three major proposals have been submitted to the IETF i.e., Googles' SPDY, Microsofts' HTTP Speed+Mobility and Network-Friendly HTTP Upgrade, but SPDY has been chosen as working draft for HTTP 2.0. In this paper we implemented MPEG-DASH over HTTP 2.0 (i.e., SPDY), demonstrating its potential benefits and drawbacks. Moreover, several experimental evaluations have been performed that compare HTTP 2.0 with HTTP 1.1 and HTTP 1.0 in the context of DASH. In particular, the protocol overhead, the performance for different round trip times, and DASH with HTTP 2.0 in a lab test scenario has been evaluated in detail.

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
Christopher Mueller Dynamic Adaptive Streaming over HTTP/2.0 3
 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
Christopher Mueller Dynamic Adaptive Streaming over HTTP/2.0 4
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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