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An Experiment To Characterize Videos On The Web. Soam Acharya Brian Smith Cornell University MMCN 1998. www. www. www. www. Overview. Designed and implemented an experiment to search and analyze videos on the web 22500 HTML documents 57000 movies 100 Gbytes of data. Why?.

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An experiment to characterize videos on the web l.jpg

An Experiment To Characterize Videos On The Web

Soam Acharya

Brian Smith

Cornell University

MMCN 1998


Overview l.jpg

www

www

www

www

Overview

  • Designed and implemented an experiment to search and analyze videos on the web

  • 22500 HTML documents

  • 57000 movies

  • 100 Gbytes of data


Slide3 l.jpg
Why?

  • Codec Designers

  • Network Engineers

  • Other Multimedia Researchers

    • MM file systems

  • Webmasters


  • Questions we asked l.jpg
    Questions We Asked

    Not all that many. We found 57,000.

    • How many movies are out there?

    • What are their basic properties?

    • What compression formats are popular?

    • How well do the formats compare?

    • Are standard modem rates enough?

    90% last 45 seconds or less. 1.1 Mbytes is their median size

    QuickTimeis about 53%, followed by MPEG (30%) and AVI

    MPEG compresses best. QuickTime and AVI are similar.

    28.8 - 128 Kilobits/sec (Kbps) are useless for real-time download and display of movies.


    Roadmap l.jpg
    Roadmap

    • Data Collection Methodology

    • Analysis

    • Results

    • Conclusion

    • Future Work

    • Open Questions


    Data collection methodology l.jpg
    Data Collection Methodology

    • Hunting Phase

      • get links to movies

    • Gathering Phase

      • download movies and gather raw statistics

    • Sifting Phase

      • eliminate outliers


    Early april 1997 hunting phase l.jpg
    Early April 1997 -Hunting Phase

    • Milked AltaVista for documents dated

      • January 1995 - March 1997

    • looked for MPEG, QuickTime, AVI

      • no streaming video format


    Gathering phase l.jpg

    www.eg.com

    2. movie.html

    LDG

    1. http://www.eg.com/movie.html

    4. summary statistics

    3. my.mov

    Http://www.eg.com/movie.html

    http://www.cnn.com/pepe.html

    …..

    www.vid.com

    Gathering Phase

    mid April 1997 - May 1997

    LP0

    LP1

    LP2

    LDG: movie link distributor/gatherer

    LP: link processor


    Sifting phase l.jpg
    Sifting Phase

    • Processed 100 Gbytes of data and 57,000 titles

      • used mpegstat and modified xanim

    • 4 <frames/sec< 40 {5000 titles}

    • duration> 0.5 seconds {1000 titles}

    • 0.6 <aspect ratio< 1.667 {1000 titles}

    • bitrate < 10 Mbps {1000 titles}

      • bitrate = (movie size)/(movie duration)

    • duplicate URL detection {1500 titles}


    Analysis l.jpg
    Analysis

    • 47500 titles remained

      • 53% QuickTime, 30% MPEG, 17% AVI

    • Can be divided into two categories

      • Distributions:

        • by date

        • fps

        • size

        • duration

        • aspect ratio

        • bitrate

      • Comparing movie formats against each other


    Slide11 l.jpg

    Roadmap

    • Data Collection Methodology

    • Analysis

    • Results

    • Conclusion

    • Future Work

    • Open Questions


    Movie size in bytes l.jpg
    Movie Size (In bytes)

    • 70% of movies are 2Mbytes or less

    • Median movie size is about 1.1 MBytes



    Aspect ratio l.jpg
    Aspect Ratio

    • 74% of all files had an aspect ratio of 1.333

      • 320 x 240

      • 160 x 120

    • 89% had aspect ratios of 1.2 - 1.5



    So far l.jpg
    So Far ...

    • Distributions:

      • by date

      • fps

      • size

      • duration

      • aspect ratio

      • bitrate

    • Comparing movie formats


    Avi quicktime comparison l.jpg

    AVIQuickTime

    Audio Codec PCM PCM

    MS-ADPCM TWOS

    AVI/QuickTime Comparison

    • 25% of AVI, 33% of QuickTime: video only

    Video CodecsAVIQuickTime

    Radius Cinepak43% 60%

    Intel Indeo R3.225% 2%

    Microsoft Video I26% 0%

    Apple Video-RPZA 0% 22%


    How compare compression l.jpg
    How Compare Compression?

    • Bits/pixel= (video size in bits)__

      (width * height * # of frames)

    Mean Median (bits/pixel)

    AVI 2.51 2.14

    QT 2.16 1.82

    MPEG 0.72 0.51


    Mpeg bits pixel distribution l.jpg
    MPEG Bits/pixel Distribution

    Frame Type Mean bits/pixel Median bits/pixel

    I 1.25 1.10

    P 0.76 0.54

    B 0.31 0.19

    • Size of I:P:B frames ~ 1: 2 : 5

    • 90% of MPEG files were video only


    Mpeg frame patterns l.jpg
    MPEG Frame Patterns

    Frame Pattern % Distribution Mean

    bits/pixel

    I 27.1 1.17

    IBBPBB 15.7 0.7

    IBBPBBPBBPBBPBB 10.4 0.31

    IBBPBBPBBPBB 8.1 0.5

    IBBBPBBBPBBB 4.4 0.66

    IPBBIBB 4.2 0.39

    IIP 3.5 0.7

    80% of MPEG: some recurring pattern


    Recap l.jpg
    Recap

    • Number of movies coming online - exponential, then flat

    • MPEG higher fps, QuickTime/AVI lower

    • Median size of movies: 1.1 Mbytes

    • 90% of movies last 45 seconds or less

    • 1.333 is the most common aspect ratio

    • 28.8 - 128 Kbps modem rates useless for real-time downloads

    • Radius Cinepak is widely used by QuickTime and AVI

    • MPEG compresses better than QuickTime and AVI

    • 80% of MPEGs have some sort of recurring pattern


    Conclusion l.jpg
    Conclusion

    • Existing compression technologies not enough for transmission over standard modems

      • explains rise of streaming video technologies

      • users cope by making file sizes, duration smaller

      • but not by throttling the bitrate

      • perceptual threshold?


    Future work l.jpg
    Future Work

    • How do videos age?

    • Another study to confirm findings

      • Brewster Kahle,

      • www.archive.org

    • Develop tools to automate the process


    Open questions l.jpg
    Open Questions

    • What are video access patterns on the Web?

    • How to analyze streaming video files?


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