CPSC Characteristics of Streaming Media Stored on the Web M. Li, M. Claypool, R. Kinicki, and J. Nichols To appear in ACM Transactions on Internet Technology, 2005.

CPSC Introduction (1/3) r Several factors contribute to the growth of streaming media on the Web m Availability of broadband m Desktop processing capabilities m Compression technology m Commercial interest r E.g., RealNetworks estimated 350,000 hours of streaming media traffic (2001) r E.g., Significant fraction of Internet traffic (CAIDA, 2002)

CPSC Introduction – Related Work (2/3) r Characterize streaming application performance (e.g., see references [10-16]) r “TCP-friendly” streaming protocols (e.g., [4],[5]) r Queuing disciplines (e.g., [6-9]) r Acharya & Smith [19] studied all video URLs available in Alta Vista in 1997 m Internet can not support real-time streaming

CPSC Introduction – Research Questions (3/3) r What are the most popular streaming media applications on the Web? m Real, Windows, QuickTime, MPEG r What is the ratio of streaming audio versus streaming video? m Audio requires lower bitrates? r Are media playback durations of stored media long-tailed? r What are typical streaming media bitrates? m Indications of bandwidth requirements r What fraction of streaming media codec's being used? m Compression efficiency

CPSC Methodology r Develop a specialized Web crawler r Traverse 17 million URLs; m Selected 17 Web pages as starting points m Considered popularity, demography, connectivity r Identified ~ 30,000 media clips m Used protocol information in URLS m E.g., rtsp://, mms:// etc r Individually access media clips using custom built tools m Encoding format, target bitrate, frame size, codec

CPSC Analysis - Outline r Aggregate analysis (Section III-A) r Commercial product analysis (Section III-B) m Video m Audio r Codec Analysis (Section III-C)

CPSC Aggregate Analysis r Each spider collected 1 million URLs m Approximately 11 million distinct URLs m About 55,000 streaming media URLs r In 1997, 23,000 streaming media URLs in 25 million Web pages m A five-fold increase in streaming! r Fig 1: ~ 1% of the servers provide 100 or more media URLs per server r Fig 2: Real Media accounts for almost half of all the streaming media URLs m QuickTime, AVI, MPEG were very popular in 1997, not any more!

CPSC Commercial Product Analysis Media TypeAudioVideoPercentage Real Windows QuickTime Total r About 98% of the streaming media URLs are for pre- recorded media r Most audio/video clips are of short duration m Median for audio ~ 4 minutes (a typical song) m Median for video ~ 2 minutes (a typical trailer) m In 1997, 90% of clips lasted 45 seconds or less m Duration still shorter than typical TV programs

CPSC Video/Audio Clips r Median bitrate ~ 200Kbps r Approximately 70% of video targeted towards broadband connections; only 1% targets T1 m In 1997, 20% videos were targeted at T1 r Scalable streaming – multiple bitrates per stream m About 12% of Windows Media streams use scalable streaming r About 50% of the videos have less than 320x240 resolution – video resolutions are low r About 90% of the streaming audio is targeted for modem users

CPSC Media Codecs r RealPlayer and Windows Media Player (latest version) buffer content at rates significantly higher than the playback rates r Raises “fairness” concern

CPSC Sampling Issues r How are the results influenced if there are fewer crawler starting points? r How are the results influenced if there are fewer than 1 million URLs per starting point? r How does sampling affect distributions? r How does choice of starting points affect distributions?

CPSC Conclusions r Streaming media on the Web increased 600% in the past 5 years r Real Media most popular, followed by Windows Media r Video and Audio are both equally popular r On-demand streaming dominates r Growth potential m Better resolutions m Higher bitrates?