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Preservation-Worthy Digital Video: Hope You Brought Your Checkbook

Preservation-Worthy Digital Video: Hope You Brought Your Checkbook. Jerome McDonough New York University November 8, 2014. Digital Video Basics. A video signal consists of luminance and chrominance information Luminance – brightness, varying from white to black (abbreviated as Y)

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Preservation-Worthy Digital Video: Hope You Brought Your Checkbook

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  1. Preservation-Worthy Digital Video: Hope You Brought Your Checkbook Jerome McDonough New York University November 8, 2014

  2. Digital Video Basics • A video signal consists of luminance and chrominance information • Luminance – brightness, varying from white to black (abbreviated as Y) • Chrominance – color (hue & saturation), conveyed as a pair of color difference signals: • R-Y (hue & saturation for red, without luminance) • B-Y (hue & saturation for blue, without luminance)

  3. Digital Video Basics • Where’s the green? • Spectral response of the human eye peaks in the green frequencies. The perceived brightness of an item can be constructed using weighted values for its red, green and blue components: • Y = 0.299R + 0.587G +0.114B, or

  4. Digital Video Basics 4:2:2 sampling 4:2:0 sampling 4:1:1 sampling 4:2:2 – High End DV (Digital Betacam, DVCPro50) 4:2:0 – MPEG 1 & 2 4:1:1 – DV and DVCAM

  5. Digital Video Basics • Why not 4:4:4 sampling? • 720 x 486 resolution = 349,920 pixels per frame • 349,920 pixels x 10 bits/sample x 3 samples/pixel = 10,497,600 bits per frame • 10,497,600 bits/frame X 29.97 frames/second = 314,613,072 bits per second • 314,613,072 bps x 3600 seconds = ~141.58 GB/hour • For 1920x1080 HDTV, more like 840 GB/hour • 4:2:2 sampling drops that rate by a third with almost no perceptible difference in quality. 4:2:0 and 4:1:1 drop it in half.

  6. Digital Video Basics • MPEG 2 Compression • Further subsampling • down sample to 8 bits/sample • down sample to 4:2:0 sampling regime • Discrete Cosine Transformation + Requantizing of coefficients from DCT • Variable Length Encoding & Run Length Encoding • Interframe compression (motion compensation) • all of which can take a 209 mbps video rate (for 4:2:2 video) and reduce it to around 8 mbps with no apparent visual loss.

  7. Digital Video Basics • Raw digital video is extremely storage and bandwidth intensive. • As a result, almost all digital video processing systems employ a mix of lossless and lossy compression mechanisms.

  8. Preservation-Worthy Digital Video • Desired characteristics for digital video we feel we can preserve include: • Content can be migrated to new formats and new media without introducing artifacts • Stored in non-proprietary, standard format which is openly documented • Easy to produce derivatives for end-user distribution • Minimize costs of production, distribution & migration

  9. Sampling, Migration & Artifacts • As in still image digitization, employing lossy compression can lead to artifacting when you migrate. • Unlike still images, lossy compression is assumed in almost all video processing technology today.

  10. One River Media Codec Test Image Images courtesy of Marco Solorio, One River Media

  11. Black Magic 8-Bit 4:2:2 Uncompressed Codec Images courtesy of Marco Solorio, One River Media

  12. Black Magic 8-Bit: 10th Generation Images courtesy of Marco Solorio, One River Media

  13. One River Codec Test Images courtesy of Marco Solorio, One River Media

  14. Digital Voodoo 10-bit Codec Images courtesy of Marco Solorio, One River Media

  15. Digital Voodoo 10-bit: 10th Gen. Images courtesy of Marco Solorio, One River Media

  16. One River Codec Test Images courtesy of Marco Solorio, One River Media

  17. Apple 4:4:4 “None”: 10th Gen. Images courtesy of Marco Solorio, One River Media

  18. Sampling, Migration & Artifacts • 4:4:4 sampling fulfills the digital promise of perfect copies across generations, but • Most video equipment doesn’t actually support it. Most high-end video editing packages on computers do and will store 4:4:4 to disk. • Lesson: if you want to store 4:4:4 uncompressed video, prepare to buy a lot of disk (or HSM), and abandon videotape.

  19. Storing 4:4:4 Uncompressed Video • QuickTime – Proprietary, but publicly documented and does the task, and software support is available • MJPEG 2000 – Open Standard (ISO/IEC 15444), supports 4:4:4 uncompressed. Software support iffy, but growing. • Material Exchange Format – Open Standard, but software support is weak, and some vendor issues

  20. Storing 4:4:4 Uncompressed Video • Videotape is a non-starter. D1 tape decks for uncompressed video cost $200K, and use 4:2:2. • Disk vs. HSM Tape • Cost vs. Speed • Opportunities to detect bit rot, ability to migrate, time to produce derivatives • Waiting on grid storage….

  21. Mind Games I: Conversion • NYU has approximately 30,000 hours of moving image material, undigitized, in its special collections. Let’s digitize 1/10 of that. • 9 Digitization/Editing workstations: $690,000 • 9 conversion staff full time for 1 year: $350,000 • 425 TB of Disk Storage @ $10k/TB = $4,250,000 • Grand Total: $5,290,000 • FYI, according to ARL, that’s nearly half our entire 2002 materials budget

  22. Mind Games II: On-going costs • Assume migration every 10 years. Assume time to migrate = 2x time of source material. • 6,000 hours x staff salary = ~$120K / 10 = $12k/year • Assume new derivatives every 5 years, and time to migrate = 2x time of source material • 12,000 hours x staff salary = ~$240k / 10 = $24k/year • 3% disk loss/year x 425 TB = 12.75 TB replaced/year. Assuming disk prices are halved every two years, for next 10 years we’d have $38,750 total replacement costs, or $3,875/year. • Grand Total: ~$40K/year maintenance costs

  23. Mind Games III • On-going maintenance costs for 3,000 hours of video on disk aren’t particularly bad. • Initial conversion costs, however, are nightmarish. • If you don’t spend the money, however, your digital video is unlikely to prove any more preservation-worthy than analog.

  24. NYU Costs: Capture Hardware Complete system cost: ~$125,000.00

  25. NYU Costs: Conversion Personnel • Currently conversion takes approximately 8 hours for every hour of tape. • Minimum personnel cost of ~$150/hour (staff time + benefits) for conversion • Hope to lower conversion time with practice (and better equipment), but at best, probably around $100/hour of tape.

  26. NYU Costs: Repository Hardware • Sun Enterprise 15K w/L700 Tape Backup: ~$400K/year • Sun T3 Disk Arrays (10 TB): ~$100K ($10K/TB)

  27. NYU Costs: Repository Personnel • Fractional part of NYU ITS Unix SysAdmin, Network Support Specialist, Tape Backup support, equivalent to about 1 FTE • ~$75K/year

  28. NYU Costs: Summary • About $475K/year to keep our server alive and happy; $10K to add another terabyte • About $125K to add a new video capture/editing workstation • About $100-150 per hour of video to pay staff capture/conversion costs

  29. The Good vs. the Perfect • Good: 1 hour of video dubbed to Digital Betacam (w/duplicate master) and converted to DVD & MPEG4 streaming derivatives • $150 staff time + $70 (2 digibeta tapes) + $3 (DVD-R blank w/case) + $24.75 (disk for MPEG4) = $247.75 • Perfect: 1 hour of video converted to 4:4:4 uncompressed on disk (w/replicated backup) w/DVD & MPEG4 streaming derivatives • $150 staff time + $2,860 (disk for master and backup) + $3 (DVD-R) + $24.75 (disk for MPEG4) = $3,037.75

  30. Affordable Perfection • Disk prices from 1992 to 2000 fell at about 45% per year. • If that holds, by 2010, the 1 TB which costs us $10,000 today will cost $276. • Storing 143 GB (one hour of 4:4:4 uncompressed video w/audio) will cost $39.50 ($4.50 more than a 60 minute Digital Betacam tape today).

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