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.
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Dynamic Adaptive Streaming over HTTP/2.0
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
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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 …
Christopher Mueller Dynamic Adaptive Streaming over HTTP/2.0 11
Christopher Mueller | dash.itec.aau.at
Alpen-Adria Universität Klagenfurt (AAU) Faculty of Technical Sciences (TEWI)
Institute of Information Technology (ITEC) Multimedia Communication (MMC)
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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