Internet Streaming Media Delivery:

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  • In 2000, 9,000 narrowband and 2,400 broadband video streams on a single physical server
  • Internet Streaming Media Delivery:

    1. 1. Internet Streaming Media Delivery: Zhen Xiao Joint work with Lei Guo, Enhua Tan, Songqing Chen, Oliver Spatchcheck, and Xiaodong Zhang Delving into A quality and Resource Utilization Perspective ACM SIGCOMM Internet Measurement Conference (IMC'06), October 2006
    2. 2. Multimedia on the Internet <ul><li>Education and research </li></ul><ul><li>News media </li></ul><ul><li>Entertainment and gaming </li></ul><ul><li>Advertisement </li></ul>
    3. 3. Streaming Media CDN/MDN Streaming server
    4. 4. Pseudo Streaming HTTP http://www.YouTube.com/ http://video.google.com/ meta file Web server
    5. 5. Streaming Media <ul><li>Thousands of concurrent streams </li></ul><ul><li>Flexible response to network congestion </li></ul><ul><li>Efficient bandwidth utilization </li></ul><ul><li>High quality to end users </li></ul><ul><li>Challenges and techniques </li></ul>
    6. 6. Existing Measurements <ul><li>Access pattern and user behaviors </li></ul><ul><ul><li>A bunch of measurement studies </li></ul></ul><ul><ul><li>Server clusters, media proxies </li></ul></ul><ul><li>Streaming mechanism and delivery quality </li></ul><ul><ul><li>Few studies </li></ul></ul><ul><li>Traffic volume … </li></ul><ul><ul><li>Downloading > pseudo streaming > streaming </li></ul></ul><ul><ul><li>(WWW’05, cookie talk 2005) </li></ul></ul><ul><ul><li>P2P >> all other media delivery systems </li></ul></ul>
    7. 7. Our Measurement <ul><li>Investigate modern streaming services </li></ul><ul><ul><li>The delivery quality and resource utilization </li></ul></ul><ul><li>Collect a large streaming media workload </li></ul><ul><ul><li>From thousands of home users and business users </li></ul></ul><ul><ul><li>Hosted by a large ISP </li></ul></ul><ul><ul><li>Packet level instead of server logs </li></ul></ul><ul><li>Analyze commonly used streaming techniques </li></ul><ul><ul><li>Automatic protocol switch </li></ul></ul><ul><ul><li>Fast Streaming </li></ul></ul><ul><ul><li>MBR encoding and rate adaptation </li></ul></ul>
    8. 8. Outline <ul><li>Traffic overview </li></ul><ul><li>Protocol rollover </li></ul><ul><li>Fast Streaming </li></ul><ul><li>Rate adaptation </li></ul><ul><li>Conclusion </li></ul>
    9. 9. Traffic Overview <ul><li>User communities </li></ul><ul><ul><li>Home user </li></ul></ul><ul><ul><li>Business user </li></ul></ul><ul><li>Media hosting services </li></ul><ul><ul><li>Self-hosting </li></ul></ul><ul><ul><li>Third-party hosting </li></ul></ul>
    10. 10. Number of requests Business users access more audio than home users
    11. 11. On-demand media: File length <ul><li>Business users tend to access longer audio/video files </li></ul>Audio Video pop songs music previews
    12. 12. On-demand media: Playback duration <ul><li>Business users tend to play audio/video longer </li></ul>Audio Video pop songs music previews
    13. 13. Live media: Playback duration <ul><li>Business users tend to access live audio/video longer </li></ul>Audio Video
    14. 14. Traffic Overview <ul><li>User communities </li></ul><ul><ul><li>Home user </li></ul></ul><ul><ul><li>Business user </li></ul></ul><ul><ul><li>Working environment affects access pattern </li></ul></ul><ul><li>Media hosting services </li></ul><ul><ul><li>Self-hosting </li></ul></ul><ul><ul><li>Third-party hosting </li></ul></ul>News and entertainment sites
    15. 15. Traffic Overview <ul><li>User communities </li></ul><ul><ul><li>Business users tend to access streaming media longer than home users </li></ul></ul><ul><ul><li>Working environment affects access pattern </li></ul></ul><ul><li>Media hosting services </li></ul><ul><ul><li>Self-hosting </li></ul></ul><ul><ul><li>Third-party hosting </li></ul></ul>
    16. 16. Media hosting services
    17. 17. Outline <ul><li>Traffic overview </li></ul><ul><li>Protocol rollover </li></ul><ul><li>Fast Streaming </li></ul><ul><li>Rate adaptation </li></ul><ul><li>Conclusion </li></ul>
    18. 18. Protocol Rollover Streaming server RTSP/UDP RTSP/TCP HTTP/TCP Embed RTSP commands in HTTP packets Media player Traffic volume: UDP: 23% TCP: 77% HTTP: rare
    19. 19. Protocol rollover time Windows media service RealNetworks media service Protocol rollover increases user startup time significantly Startup latency = protocol rollover time + transport setup time + startup buffering time
    20. 20. Protocol selection and rollover avoidance <ul><li>Most streaming traffic are TCP-based </li></ul><ul><ul><li>The usage of NAT? </li></ul></ul><ul><ul><li>MMS clients report private IP address in clear text </li></ul></ul><ul><ul><ul><li>Home user: 98.3% report 192.168.*.* </li></ul></ul></ul><ul><ul><ul><li>Business user: 89.5% report 192.168.*.* </li></ul></ul></ul><ul><li>Protocol rollover sessions are minor </li></ul><ul><ul><li>Home user: 7.37% </li></ul></ul><ul><ul><li>Business user: 7.95% </li></ul></ul><ul><li>Most streaming sessions use TCP directly </li></ul><ul><ul><li>Why? </li></ul></ul>
    21. 21. Protocol selection and rollover avoidance <ul><li>Windows media service </li></ul><ul><ul><li>Specify the protocol in the media meta file </li></ul></ul><ul><ul><li>Use URL modifiers to avoid protocol rollover </li></ul></ul><ul><ul><li>Ex: rtspt://xxx.xxx.com:/xxx.wmv </li></ul></ul><ul><ul><li>More than 70% </li></ul></ul><ul><li>RealNetworks media service </li></ul><ul><ul><li>NAT transversal techniques </li></ul></ul>
    22. 22. Outline <ul><li>Traffic overview </li></ul><ul><li>Protocol rollover </li></ul><ul><li>Fast Streaming </li></ul><ul><li>Rate adaptation </li></ul><ul><li>Conclusion </li></ul>
    23. 23. Fast Streaming <ul><li>Fast Streaming: deliver media data “faster” than its encoding rate </li></ul><ul><ul><li>Fast start </li></ul></ul><ul><ul><li>Fast cache </li></ul></ul><ul><ul><li>Fast recovery </li></ul></ul><ul><ul><li>Fast reconnect </li></ul></ul><ul><li>Always TCP-based </li></ul>
    24. 24. Media objects delivered with Fast Cache (VoD home user workload) File length Encoding rate Fast Cache is more widely used for media files with longer length and higher encoding rate.
    25. 25. Bandwidth Utilization PLAY RTSP/1.0 Bandwidth: 1.12 Mbps Speed: 20.5 RTSP /1.0 200 OK Speed: 5 Fast Cache Normal TCP
    26. 26. Fast Cache smooth bandwidth fluctuation Rebuffer ratio = rebuffer time / play time Fast Cache Normal TCP
    27. 27. Fast Cache produces extra traffic Most streaming sessions only request the initial part of a media object Over supplied data Fast Cache: 55% Normal TCP: 5%
    28. 28. Server response time Third party media service Self-hosting media service DESCRIBE foo.wmv RTSP/1.0 RTSP /1.0 200 OK SDP RTT SRT sniffer
    29. 29. Server Load Windows media load simulator Windows Server 2003 Win XP Server log … Ethernet 1 X 4 X Some CDNs/MDNs do not support Fast Cache at all
    30. 30. Outline <ul><li>Traffic overview </li></ul><ul><li>Protocol rollover </li></ul><ul><li>Fast Streaming </li></ul><ul><li>Rate adaptation </li></ul><ul><li>Conclusion </li></ul>
    31. 31. Rate Adaptation 96Kbps 128Kbps 320Kbps … 1.128Mbps Multiple-bit-rate encoding Stream switch WM: Intelligent streaming RM: SureStream Stream thinning: deliver key frame only Video cancellation
    32. 32. MBR encoding on-demand audio live audio audio stream in video objects video stream in video objects 42% on-demand video are MBR encoded
    33. 33. Stream switch 30 sec 60% Streaming switch latency Low quality duration 3 sec 40% Play-out buffer Stream switch is often not smooth
    34. 34. Stream thinning 30 sec 70%
    35. 35. Fast Cache and stream switch Do not work with each other: fewer stream switches than MBR encoded objects playing buffering playing buffering buffering playing 5 sec When network congestion occurs … Like pseudo streaming When rebuffer occurs time fill play-out buffer
    36. 36. Streaming quality and playback duration Home user business user Longer duration sessions have higher prob. of quality degradation Business user workload has more quality degradation >100 sec 88%
    37. 37. Streaming quality summary The quality of media streaming on the Internet leaves much to be improved
    38. 38. Coordinating caching and rate adaptation <ul><li>Fast Cache: aggressively buffer data in advance </li></ul><ul><ul><li>Over-utilize CPU and bandwidth resources </li></ul></ul><ul><ul><li>Neither performance effective nor cost-efficient </li></ul></ul><ul><li>Rate adaptation: conservatively switch to lower bit rate stream </li></ul><ul><ul><li>Switch handoff latency </li></ul></ul><ul><li>Coordinated Streaming </li></ul>Upper bound Prevent aggressive buffering Lower bound Prevent switch latency
    39. 39. Coordinated Streaming Rebuffering ratio Over-supplied data Switch latency
    40. 40. Conclusion <ul><li>Quality of Internet streaming </li></ul><ul><ul><li>Often unsatisfactory </li></ul></ul><ul><ul><li>Need to improve </li></ul></ul><ul><li>Modern streaming media services </li></ul><ul><ul><li>Over-utilize CPU and bandwidth resources </li></ul></ul><ul><ul><li>Not a desirable way to improve quality </li></ul></ul><ul><li>Coordinated Streaming </li></ul><ul><ul><li>Combine merits of both caching and rate adaptation </li></ul></ul><ul><ul><li>Simple but effective </li></ul></ul>

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