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Delving into
Internet Streaming Media Delivery:
   A quality and Resource Utilization Perspective

        Written by: Lei...
Multimedia: Downloading
 Web browser
                HTTP



                                  Web Server



             ...
Multimedia: Pseudo Streaming

   Web browser



                      Web Server




Media player
Multimedia: Streaming
Web browser
                  HTTP



                                 Web Server



               ...
Streaming Media
• Merits
    –   Thousands of concurrent streams
    –   Flexible response to network congestion
    –   E...
Motivation
• Modern streaming techniques
  concentrated on the techniques of
  – media access pattern and
  – user behavio...
Objective and approach
• Understand modern streaming techniques
   – The delivery quality and resource utilization

• Coll...
• Trace Collection and processing
  Methodology
• Traffic Overview
• Fast Streaming
• Rate Adaptation
• Protocol Rollover
...
Trace Collection and
       processing methodology
• Collect streaming packet
• Capture all TCP packet within ports 554-55...
• Trace Collection and processing
  Methodology
• Traffic Overview
• Fast Streaming
• Rate Adaptation
• Protocol Rollover
...
Traffic Overview
• User communities
  – Home users in a cable network
  – Business users hosted by a big ISP
  – Have diff...
Traffic Overview
• Access Pattern
  – Business users access more audio than home users
  – Business users tend to access l...
• Trace Collection and processing
  Methodology
• Traffic Overview
• Fast Streaming
• Rate Adaptation
• Protocol Rollover
...
Fast streaming
• A combination of techniques
                 Transmits data as fast as possible until
  – Fast start   th...
Fast streaming
• A combination of techniques
  – Fast start

  – Fast cache

  – Fast recovery
  – Fast reconnect       40...
Smooth bandwidth flucation
• Rebuffering ratio Rebuffer ratio = rebuffer time / play time
• Less rebuffering ratio then no...
Production of extra traffic
• Oversupplies media to the client when client early
  terminate the media service
• Over-supp...
Server Response time
• Longer time to be served
• 43% of request longer than 0.1 s running on Fast Cache
  while only 9% o...
Server load
• 3.6 times higher server load than normal
  TCP streaming

 Server log

        1X    4X            1X       ...
Effectiveness ?
• Throughput (rebuffer ratio) of Fast Streaming similar to
  that of TCP streaming
   – Only feasible when...
• Trace Collection and processing
  Methodology
• Traffic Overview
• Fast Streaming
• Rate Adaptation
• Protocol Rollover
...
Challenges of Streaming
• Bandwidth fluctuation
  – Quality of media streaming may significantly
    degrade
• Connection ...
Challenges of Streaming
• Under the situation of bandwidth
  fluctuation, a technique of Rate Adaptation
  is widely used ...
Rate Adaptation
• In order to adapt to bandwidth fluctuation,
  major media services support three kinds
  of techniques f...
Rate Adaptation
• Stream Switch
  – Multiple bit rates (MBR) must be used
  – According to the statistic of the paper, MBR...
MBR Encoding
          on-demand audio         audio stream in video objects




             live audio            video ...
How it works

          DESCRIBE




               PLAY


Setup     Streaming content
How it works
• When bandwidth drops

          Request to switch to lower rate stream




• WM sends command with a body s...
How it works
• During transmission, if the bandwidth
  decreases, the server automatically
  detects the change and switch...
Problem Occurs
• After extracting and analyzing information
  from RTSP/MMS commands, switch
  latency occurs
• Switch lat...
Problem Occurs
• 30%~40% of stream switches have
  latency greater than 3 seconds
• 10%~20% of stream switches have
  late...
Stream Thinning
• Similar to stream switch
• If the bandwidth can no longer support the
  streaming video, the image quali...
Stream Thinning
• 70% of the thinning duration are shorter
  than 30 seconds
• 70% in the home users and 82% in the
  busi...
Video Cancellation
• When the bandwidth is too low to transmit
  the key frame of video stream, the client
  may send a TE...
• Trace Collection and processing
  Methodology
• Traffic Overview
• Fast Streaming
• Rate Adaptation
• Protocol Rollover
...
Protocol Rollover
• Streaming protocol: UDP, TCP, HTTP

Delivery over UDP X   Delivery over TCP X HTTP

• Due the wide dep...
Protocol Rollover
                SETUP (UDP)
CASE 1:
                 Return UDP



                SETUP (UDP)
CASE 2:
 ...
Protocol Rollover
• In the collected data, if protocol rollover
  occurs, it tried to establish UDP from 1 to
  3 times be...
Protocol Rollover
• In home user workload, only 7.37% of
  streaming session trying UDP first then
  switching to TCP.
• I...
Protocol Selection & Rollover
             Avoidance
• The phenomenon can be explained as following:
• Windows streaming s...
Protocol Selection & Rollover
             Avoidance
• The conjecture is:
  – Content providers are aware of NAT/firewalls...
Proof
• Further investigate the NAT usage with
  MMS
• Different from RTSP, clients report local IP
  address to server
• ...
• Trace Collection and processing
  Methodology
• Traffic Overview
• Fast Streaming
• Rate Adaptation
• Protocol Rollover
...
Coordinating caching and rate adaptation

• Fast Cache: aggressively buffer data in advance
   – Over-utilize CPU and band...
Results
• Rebuffering ratio is close to zero
• Reduces 77% over-supplied traffic
  produced by Fast Cache, though still no...
• Trace Collection and processing
  Methodology
• Traffic Overview
• Fast Streaming
• Rate Adaptation
• Protocol Rollover
...
What We Learn and What We
              Think
• This paper mainly aim at investigating the
  current streaming technique u...
What We Learn and What We
             Think
• More research papers are written by same
  group of people
• More study are...
Thank You!
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Transcript of "Delving into Internet Streaming Media Delivery:"

  1. 1. Delving into Internet Streaming Media Delivery: A quality and Resource Utilization Perspective Written by: Lei Guo, Enhua Tan, Songqing Chen, Zhen Xiao, Oliver Spatscheck, Xiaodong Zhang Presented by: Harris C.C. Sun Dicky Kwok
  2. 2. Multimedia: Downloading Web browser HTTP Web Server Long start-up latency Potential waste of traffic Media player
  3. 3. Multimedia: Pseudo Streaming Web browser Web Server Media player
  4. 4. Multimedia: Streaming Web browser HTTP Web Server RTSP/MMS/HTTP RTP/RTCP Media player Streaming Server
  5. 5. Streaming Media • Merits – Thousands of concurrent streams – Flexible response to network congestion – Efficient bandwidth utilization – High quality to end users • Challenges – Lack of QoS on the Internet – Diverse network connection of users – Prolonged startup latency • Research and techniques – Effective utilization of server and Internet resources – Mechanism of streaming media delivery • Protocol rollover, • Fast Streaming, • MBR and • rate adaptation
  6. 6. Motivation • Modern streaming techniques concentrated on the techniques of – media access pattern and – user behaviors to improve streaming performance. • Few focused on – the improvement of techniques for quality streaming delivery and – the effective utilization of media resource.
  7. 7. Objective and approach • Understand modern streaming techniques – The delivery quality and resource utilization • Collect a large streaming media workload – From thousands of home users and business users Hosted by a large ISP (Gigascope) – RTSP, RTP/RTCP, MMS, RDT packet headers instead of server logs • Analyze commonly used streaming techniques – Fast Streaming – Protocol rollover – MBR encoding and rate adaptation • Propose a coordinated streaming mechanism – Effectively coordinate the merits from caching and rate adaptation
  8. 8. • Trace Collection and processing Methodology • Traffic Overview • Fast Streaming • Rate Adaptation • Protocol Rollover • Coordinated Streaming • Summary
  9. 9. Trace Collection and processing methodology • Collect streaming packet • Capture all TCP packet within ports 554-555, 7070-7071 9070 and 1755 • Keywords matching to collect RTSP and MMS packet • Group TCP packet by IP addresses, port, TCP SYN/FIN/RST flag • Extract streaming command from each request • Identify media data and control packet
  10. 10. • Trace Collection and processing Methodology • Traffic Overview • Fast Streaming • Rate Adaptation • Protocol Rollover • Coordinated Streaming • Summary
  11. 11. Traffic Overview • User communities – Home users in a cable network – Business users hosted by a big ISP – Have different access patterns • Media hosting services – Self-hosting – Third-party hosting
  12. 12. Traffic Overview • Access Pattern – Business users access more audio than home users – Business users tend to access longer audio/video files – Business users tend to play audio/video longer – Business users tend to access live audio/video longer • Media Hosting Service – Self-hosting: yahoo.com, aol.com, wbr.com – Third-party hosting: akamai.com. LimeLight Networks, fplive.net
  13. 13. • Trace Collection and processing Methodology • Traffic Overview • Fast Streaming • Rate Adaptation • Protocol Rollover • Coordinated Streaming • Summary
  14. 14. Fast streaming • A combination of techniques Transmits data as fast as possible until – Fast start the play-out buffer is filled. – Fast cache Streams media data up to 5 times the encoding rate – Fast recovery Rare in workload traffic, not include – Fast reconnect them in study
  15. 15. Fast streaming • A combination of techniques – Fast start – Fast cache – Fast recovery – Fast reconnect 40% 60%
  16. 16. Smooth bandwidth flucation • Rebuffering ratio Rebuffer ratio = rebuffer time / play time • Less rebuffering ratio then normal TCP streaming
  17. 17. Production of extra traffic • Oversupplies media to the client when client early terminate the media service • Over-supplies about 54.8% of media data on average, while TCP streaming over-supplies about 4.8% data only. Normal TCP: < 5% oversupplied Fast Cache: > 55% oversupplied
  18. 18. Server Response time • Longer time to be served • 43% of request longer than 0.1 s running on Fast Cache while only 9% of request longer than 0.1 s in TCP streaming • Fast cache is statistically longer than that on servers not running Fast Cache Third party media service Self-hosting media service > 40% 20 ms
  19. 19. Server load • 3.6 times higher server load than normal TCP streaming Server log 1X 4X 1X 4X CPU
  20. 20. Effectiveness ? • Throughput (rebuffer ratio) of Fast Streaming similar to that of TCP streaming – Only feasible when bandwidth is large enough – Less possibility of congestion in this case Encoding rate: 200 – 320 K bps Bandwidth: > 500 Kbps Fast Cache: not resource-efficient
  21. 21. • Trace Collection and processing Methodology • Traffic Overview • Fast Streaming • Rate Adaptation • Protocol Rollover • Coordinated Streaming • Summary
  22. 22. Challenges of Streaming • Bandwidth fluctuation – Quality of media streaming may significantly degrade • Connection of speed varies – From dial-up to cable • Prolonged startup latency
  23. 23. Challenges of Streaming • Under the situation of bandwidth fluctuation, a technique of Rate Adaptation is widely used by media players • The basic concept is simple. – modify the stream bit rate to adapt the various bandwidth – Resume when bandwidth recovers – Never higher than original bit rate
  24. 24. Rate Adaptation • In order to adapt to bandwidth fluctuation, major media services support three kinds of techniques for rate adaptation. – Stream switch (also known as Intelligent Streaming in WM and SureStream in RealNetwork) – Stream thinning – Video Cancellation
  25. 25. Rate Adaptation • Stream Switch – Multiple bit rates (MBR) must be used – According to the statistic of the paper, MBR encoding technique is widely used in media authoring
  26. 26. MBR Encoding on-demand audio audio stream in video objects live audio video stream in video objects 42% on-demand video are MBR encoded with at least two video stream The maximum numbers of streaming is 20
  27. 27. How it works DESCRIBE PLAY Setup Streaming content
  28. 28. How it works • When bandwidth drops Request to switch to lower rate stream • WM sends command with a body specifying current stream and new stream • REAL sends UNSUBSCRIBE to cancel the current stream, and SUBSCRIBE to switch to new stream
  29. 29. How it works • During transmission, if the bandwidth decreases, the server automatically detects the change and switches to a stream with a lower bit rate. If bandwidth improves, the server switches to a stream with a higher bit rate, but never higher than the original bit rate. (from Microsoft page)
  30. 30. Problem Occurs • After extracting and analyzing information from RTSP/MMS commands, switch latency occurs • Switch latency occurs as the freezing duration between old stream and new stream • User has to wait for re-buffering • Low quality duration appears
  31. 31. Problem Occurs • 30%~40% of stream switches have latency greater than 3 seconds • 10%~20% of stream switches have latency greater than 5 seconds • 60% of sessions have low quality duration less than 30 seconds • 85% are shorter than 40 seconds • Non-trivial for end users
  32. 32. Stream Thinning • Similar to stream switch • If the bandwidth can no longer support the streaming video, the image quality will be degraded in order to avoid buffering • Thinning interval is defined as the interval between two consecutive stream thinning events
  33. 33. Stream Thinning • 70% of the thinning duration are shorter than 30 seconds • 70% in the home users and 82% in the business users, the thinning intervals are longer than 30 seconds
  34. 34. Video Cancellation • When the bandwidth is too low to transmit the key frame of video stream, the client may send a TEARDOWN command to cancel the video streaming • After that, the server maintains the continuous audio steam only • If the bandwidth increases, the client may set up and request the video streaming again
  35. 35. • Trace Collection and processing Methodology • Traffic Overview • Fast Streaming • Rate Adaptation • Protocol Rollover • Coordinated Streaming • Summary
  36. 36. Protocol Rollover • Streaming protocol: UDP, TCP, HTTP Delivery over UDP X Delivery over TCP X HTTP • Due the wide deployment of NAT routers/firewalls in both home and business users, protocol rollover results in great affect of startup latency
  37. 37. Protocol Rollover SETUP (UDP) CASE 1: Return UDP SETUP (UDP) CASE 2: Return TCP SETUP (UDP) CASE 3: Return UDP
  38. 38. Protocol Rollover • In the collected data, if protocol rollover occurs, it tried to establish UDP from 1 to 3 times before switching to TCP • Protocol rollover takes non-trivial time, increase the startup latency • The default protocol in client is usually UDP • However, some interesting results are revealed by the data.
  39. 39. Protocol Rollover • In home user workload, only 7.37% of streaming session trying UDP first then switching to TCP. • In business user workload, only 7.95% in the streaming session. • These imply that TCP is directly used without protocol rollover in most streaming. • What happened?
  40. 40. Protocol Selection & Rollover Avoidance • The phenomenon can be explained as following: • Windows streaming service allows the specification of protocol in URL modifier at client side or server side – Content provider: use URL modifier to specify protocol in the meta file – rtspt://xxx.xxx.com:/xxx.wmv (TCP) >70% – rtspu://xxx.xxx.com:/xxx.wmv (UDP) rarely • After extracting URL modifier, 70% of streaming session is specified as TCP
  41. 41. Protocol Selection & Rollover Avoidance • The conjecture is: – Content providers are aware of NAT/firewalls – Understand UDP is mostly shielded by clients – They actively use TCP to avoid shielding or protocol rollover – Even if UDP is supported, the streaming is delivered over TCP directly
  42. 42. Proof • Further investigate the NAT usage with MMS • Different from RTSP, clients report local IP address to server • Most users report private IPs • Indicate that clients access internet through NAT
  43. 43. • Trace Collection and processing Methodology • Traffic Overview • Fast Streaming • Rate Adaptation • Protocol Rollover • Coordinated Streaming • Summary
  44. 44. Coordinating caching and rate adaptation • Fast Cache: aggressively buffer data in advance – Over-utilize CPU and bandwidth resources – Neither performance effective nor cost-efficient • Rate adaptation: conservatively switch to lower bit rate stream – Switch handoff latency • Coordinated Streaming high rate stream low rate stream Lower bound Upper bound Prevent switch latency Prevent aggressive buffering
  45. 45. Results • Rebuffering ratio is close to zero • Reduces 77% over-supplied traffic produced by Fast Cache, though still not as good as TCP streaming • Switch handoff latency is nearly zero
  46. 46. • Trace Collection and processing Methodology • Traffic Overview • Fast Streaming • Rate Adaptation • Protocol Rollover • Coordinated Streaming • Summary
  47. 47. What We Learn and What We Think • This paper mainly aim at investigating the current streaming technique used by media players • Most people enjoy video streaming but seldom know the theory behind • Modern streaming services over-utilize CPU and bandwidth resource • Coordinated Streaming is suggested • Ideal theory but not sure if it works in reality.
  48. 48. What We Learn and What We Think • More research papers are written by same group of people • More study are needed
  49. 49. Thank You!
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