Practical Session:                     Digitisation TechnologyBasics of Audio Gramophone records 1/4” tapeBasics of Vi...
Audio            Gramophone records                 −   Lacquer = transcription masters                 −   Shellac = 78s...
Grams: What the British Library Sound Archive usesTechnics turntable, made in JapanAnd modified in USA by Kabusa  4-5 Sept...
Digitising grams (records)            Batch processing            Inspection            Cleaning            Correct pl...
Batch processing            The key to efficiency            Organise item into groups of the same type        and condi...
Cleaning            Shellac: only pure de-ionized water and a        wetting agent (eg Kodak PhotoFlo)                 − ...
Ultrasonic bath          This is a       standard bath,       not made       specifically for       audio work          ...
Playback Speed    Only a problem for older shellac records,    pre-1925    Speed of playback can be changed after    dig...
Strobe DiscFree online  from  vinyl-  engine  4-5 September 2012   Vietnam Film Institute Workshops   9 http://www.vinylen...
Correct Needle and Weight            British Library Sound Archive uses one stylus for vinyl =        micro groove = Shur...
Correct Equalisation            Need a special pre-amplifier with adjustable        equalisation for recordings made befo...
Standards for Audio            Digitise at minimum of 16-bit, 44.1 kHz =        CD quality (BBC uses this)            “2...
Digitisation            Needs an external sound card or        equivalent – do NOT use the digitisation        built into...
Audio Tape            1/4” open reel, 1950s to about 2000; 1/8”        cassette, late 1970s to now            Others: 8-...
Open-Reel Tape Deck4-5 September 2012   Vietnam Film Institute Workshops   15
Speed    Cassettes usually only one speed= 1 7/8    Open reel: 15/16, 1 7/8, 3 3/4, 7 ½, 15, 30    3 ¾ and 7 ½ common f...
Track layout    Usually 2 or 4 tracks, but many    arrangements (depending upon head type,    and mono vs stereo)    Com...
Two-track:Mono and either dual-mono or stereoFour track: typical stereo and either stereo or dual- mono  4-5 September 201...
Varieties of Tape Heads   The 2 channel    heads are very    common; they can    be used for stereo    or mono.   The 4 ch...
Sticky-shed    Oxide comes off the backing    Caused by absorption of moisture    Fixed by baking: 24 hrs at 45 degrees...
Extreme Tape Shedding4-5 September 2012         Vietnam Film Institute Workshops   21
Azimuth    If the playback head is not at the same    angle as the record head, the high    frequencies are reduced    S...
Heads    Worn – inspect and repair or replace    Dirty – clean after every ½ day of use !!!        −   Use cotton buds a...
4-5 September 2012   Vietnam Film Institute Workshops   24
Video            Much harder than audio – except for        domestic formats            Presto has online training video...
Film            Threats: Vinegar Syndrome, shrinkage,        damage, dust            Issues: A/B rolls, splices        ...
Digitisation of Film    Telecine vs Datacine    Resolution    Bit Depth    Digital Formats
Telecine vs Datacine    Telecine: real-time (to videotape recorder)        −   Video output (interlaced fields)        − ...
Resolution    SD 704 x 576 (480 USA)    HD 1440 x 1080 = 4x3 (1920x1080 ??)    2k 2048 x 1556 = 4x3 (almost)    4k 409...
Resolution: Dutch Archive            High-level cinema (Lawrence of Arabia)        fully captured at 6000 horizontal pixe...
Bit Depth    Dutch archive uses 10-bit log scale (which is what    most equipment produces)    Presto recommended at lea...
Bit Depth Examples    1, 2, 4 and 8 bit illustrations:http://en.wikipedia.org/wiki/List_of_monochrome_and_RGB_   palettes
4-bit Linear vs 3-bit Log         4 bit linear = 16 steps                                                    3 bit linear,...
Digital Formats for Film    DPX uncompressed, very flexible    DCI DCDM = Digital Cinema Distribution    Master: 2048x10...
Discussion    Who is doing digitisation?    What formats?    What equipment?    What results?    What problems?
Tea Time    Next: Digital Preservation Strategy    Format Roadmap    Digital Storage Technology    Estimating Costs  ...
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Workshop 3 audiovisual digitisation technology

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How to digitise audio, video and film

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  • General Information IASA TC-04 http://www.iasa-web.org/tc04/audio-preservation CLIR: http://www.clir.org/pubs/reports/pub137/reports/pub137/contents.html Television Technical Theory: Unplugged http://www.danalee.ca/ttt/index.htm
  • http://en.wikipedia.org/wiki/ Gramophone_record#Early_speeds Free strobe disc patterns online: http://www.vinylengine.com/strobe-discs.shtml
  • Apogee: http://apogeedigital.com/products/ symphony-io-configurations.php Sadie: http://www.sadie.com/ Cedar restoraton tools: http://www.cedar-audio.com/ Review of cheaper systems: http://www.pcworld.com/ article/220784/digitize_your_music.html Presonus's $200 Audiobox USB, Avid's $330 Pro Tools Mbox Mini, or Focusrite's $200 Saffire 6. http://www.presonus.com/products/AudioBox-USB http://www.avid.com/US/products/Mbox-Mini http://uk.focusrite.com/ usb-audio-interfaces/saffire-6-usb
  • http://en.wikipedia.org/wiki/ Reel-to-reel_audio_tape_recording
  • Tracks: http://virtual.yosemite.cc.ca.us/ jchappell/images/5revised.jpg Heads: http://www.danalee.ca/ttt/appendices.htm
  • http://www.thegreatbear.net/transfer-audio-tape/ Tape-baking-sticky-shed-syndrome/
  • discussion: http://www.tapeheads.net/showthread.php?t=3700 Photo: http://www.angelfire.com/electronic2/vintagetx/Recording.html
  • BFI Tour http://vimeo.com/44836302
  • http://en.wikipedia.org/wiki/Standard-definition_television http://en.wikipedia.org/wiki/4K_resolution
  • White Paper: Film scanning considerations p 12 filmscanning_v1.04.pdf For example the MTF method has been used for a demo calculation of the resolution needed to capture all detail in the movie Lawrence of Arabia. The conclusion was that a horizontal resolution of 6.000 pixels would be sufficient given that one has to take into account that this movie was shot in highly professional conditions on 65mm negative with very good lenses and film stock. If the outcome of this example would be translated to the predominant film stock stock in the Sound and Vision archive, i.e. 16 mm reversal material, the resolution needed would be 1.470 pixels horizontally. Even lower resolutions would be a safe assumption when taking into account that it concerns positive reversal and is shot for broadcast news, current affairs and documentaries in far from ideal conditions.
  • http://motion.kodak.com/motion/about /the_storyboard/17788/index.htm
  • Table 3.1. Relation of negative densities and 10 bit log code values. Label Density Above Base Log Code Value (10 Bit) D-Min[1] 0.00 95 0.01 102 0.02 107 0.05 122 0.11 151 2% Gray [2] 0.17 180 0.23 212 0.30 244 0.36 277 0.43 309 0.49 341 0.56 373 0.62 406 0.69 438 18% Gray [3] 0.75 470 0.81 501 0.87 531 0.93 562 1.00 593 1.06 624 1.12 654 90% White [4] 1.18 685 1.24 716 1.30 746 1.36 777 1.43 808 1.49 839 1.55 869 D-Max [5] 1.61 900 1.67 931 1.73 961 1.79 992 1.86 1023 http://www.acvl.org/digital_intermediates/dicompanion/ch03.html
  • Workshop 3 audiovisual digitisation technology

    1. 1. Practical Session: Digitisation TechnologyBasics of Audio Gramophone records 1/4” tapeBasics of Video Set-up for a transfer Special problems: stability, colour, audioBasic of Film Telecine vs Datacine Resolution, bit depth Grading (colour correction), workflow4-5 September 2012 Vietnam Film Institute Workshops 1
    2. 2. Audio  Gramophone records − Lacquer = transcription masters − Shellac = 78s − Vinyl = 45s, LPs  1/4” tape = 6mm tape  Many other formats, including digital: CD, DAT, minidisc (MD), audio on videotape4-5 September 2012 Vietnam Film Institute Workshops 2
    3. 3. Grams: What the British Library Sound Archive usesTechnics turntable, made in JapanAnd modified in USA by Kabusa 4-5 September 2012 Vietnam Film Institute Workshops 3
    4. 4. Digitising grams (records)  Batch processing  Inspection  Cleaning  Correct playback speed  Choosing the correct needle and weight  Correct equalisation contour4-5 September 2012 Vietnam Film Institute Workshops 4
    5. 5. Batch processing  The key to efficiency  Organise item into groups of the same type and condition  Ideally: everything controlled through the workflow with bar codes4-5 September 2012 Vietnam Film Institute Workshops 5
    6. 6. Cleaning  Shellac: only pure de-ionized water and a wetting agent (eg Kodak PhotoFlo) − 1 part agent to 200 parts water  Vinyl: water and alcohol (industrial-grade metholated spirits); mix 50-50  Can be done manually, or can buy machines (Keith Monks, Nitty Gritty)4-5 September 2012 Vietnam Film Institute Workshops 6
    7. 7. Ultrasonic bath  This is a standard bath, not made specifically for audio work  Used for very dirty objects, before final cleaning4-5 September 2012 Vietnam Film Institute Workshops 7
    8. 8. Playback Speed Only a problem for older shellac records, pre-1925 Speed of playback can be changed after digitisation, so just need to get close Document what you do! Also should check to ensure turntable is operating at correct speed: strobe, tachonometer (strobe built into Technics)
    9. 9. Strobe DiscFree online from vinyl- engine 4-5 September 2012 Vietnam Film Institute Workshops 9 http://www.vinylengine.com
    10. 10. Correct Needle and Weight  British Library Sound Archive uses one stylus for vinyl = micro groove = Shure N44-7 = “0.7 mil”  Uses three sizes for shellac: 0.0028, 0.0035 and 0.0040 inches (= “4 thou” or “4 mil” or “4.0 CT”)  In metric: 1 thou = 1 mil = 25.4 micron (= μm = micro meter) = 0.0254 mm  2.8, 3.5, 4.0 thou = 70, 90, 100μm = 0.07, 0.09, 0.1mm  The stylus will come with a recommended weight − 1.5 to 3 grams for modern equipment4-5 September 2012 Vietnam Film Institute Workshops 10
    11. 11. Correct Equalisation  Need a special pre-amplifier with adjustable equalisation for recordings made before approx 1954  BUT – frequency response can be re-shaped after digitisation if necessary  Need RIAA equalisation after 1954  So – document what you do !4-5 September 2012 Vietnam Film Institute Workshops 11
    12. 12. Standards for Audio  Digitise at minimum of 16-bit, 44.1 kHz = CD quality (BBC uses this)  “24-bit” at 96 kHz is IASA recommendation − IASA TC-04 is the standard reference for preservation-quality audio digitisation “Guidelines on the Production and Preservation of Digital Audio Objects” - IASA Technical Committee Save as BWF=Broadcast Wave File= .wav + metadata4-5 September 2012 Vietnam Film Institute Workshops 12
    13. 13. Digitisation  Needs an external sound card or equivalent – do NOT use the digitisation built into a PC (high noise => 8 bits)  British Library recommends Rosetta from Apogee http://www.apogeedigital.com  BBC recommends Sadie  MANY cheaper solutions possible (notes)4-5 September 2012 Vietnam Film Institute Workshops 13
    14. 14. Audio Tape  1/4” open reel, 1950s to about 2000; 1/8” cassette, late 1970s to now  Others: 8-track cartridge, multi-track pro  Problems: speed, track layout, tape type  More: sticky-shed, azimuth, head condition  More: Dolby noise reduction systems4-5 September 2012 Vietnam Film Institute Workshops 14
    15. 15. Open-Reel Tape Deck4-5 September 2012 Vietnam Film Institute Workshops 15
    16. 16. Speed Cassettes usually only one speed= 1 7/8 Open reel: 15/16, 1 7/8, 3 3/4, 7 ½, 15, 30 3 ¾ and 7 ½ common for domestic use 7 ½ and 15 common for professional use
    17. 17. Track layout Usually 2 or 4 tracks, but many arrangements (depending upon head type, and mono vs stereo) Common: − Mono 2-track − Stereo 2-track − Stereo 4-track
    18. 18. Two-track:Mono and either dual-mono or stereoFour track: typical stereo and either stereo or dual- mono 4-5 September 2012 Vietnam Film Institute Workshops 18Non-standard:
    19. 19. Varieties of Tape Heads The 2 channel heads are very common; they can be used for stereo or mono. The 4 channel can play back most anything.4-5 September 2012 Vietnam Film Institute Workshops 19
    20. 20. Sticky-shed Oxide comes off the backing Caused by absorption of moisture Fixed by baking: 24 hrs at 45 degrees C, with 2 to 3 hours to heat up, and 2 to 3 hours to cool down BBC: “we dont bake” (so use tape cleaning equipment instead)
    21. 21. Extreme Tape Shedding4-5 September 2012 Vietnam Film Institute Workshops 21
    22. 22. Azimuth If the playback head is not at the same angle as the record head, the high frequencies are reduced Solutions: 1) every tape recorder perfect; 2) adjust azimuth on playback – and listen to high frequencies (could use meter) Usually takes a screw driver or an Allen key to make the adjustment
    23. 23. Heads Worn – inspect and repair or replace Dirty – clean after every ½ day of use !!! − Use cotton buds and isopropyl alcohol Magnetised – demagnetise every month
    24. 24. 4-5 September 2012 Vietnam Film Institute Workshops 24
    25. 25. Video  Much harder than audio – except for domestic formats  Presto has online training video for 2”, 1” and U-Matic http://digitalpreservation.ssl.co.uk/training/2460/2542.html  Many many possible faults in playback  Use a time-base corrector, possibly a filter, and the best colour decoder available4-5 September 2012 Vietnam Film Institute Workshops 25
    26. 26. Film  Threats: Vinegar Syndrome, shrinkage, damage, dust  Issues: A/B rolls, splices  Wide variety of film types: reversal, B&W vs colour, positive vs negative  Master neg, interneg, print4-5 September 2012 Vietnam Film Institute Workshops 26
    27. 27. Digitisation of Film Telecine vs Datacine Resolution Bit Depth Digital Formats
    28. 28. Telecine vs Datacine Telecine: real-time (to videotape recorder) − Video output (interlaced fields) − Video resolution: SD, HD − Video bit depth: 8 or 10 bit max − Video aspect ratios: 12:9, 16:9 Datacine: produces a file, solves ALL the above problems Telecine excellent for access copies, but poor for preservation
    29. 29. Resolution SD 704 x 576 (480 USA) HD 1440 x 1080 = 4x3 (1920x1080 ??) 2k 2048 x 1556 = 4x3 (almost) 4k 4096 x 3112 (maybe)From wikipedia:Standard Resolution Aspect R PixelsDigital cinema 4K 4096 × 1714 2.39:1 7,020,544Digital cinema 4K 3996 × 2160 1.85:1 8,631,360Academy 4K 3656 × 2664 1.37:1 9,739,584Full Aperture 4K 4096 × 3112 1.32:1 12,746,752
    30. 30. Resolution: Dutch Archive  High-level cinema (Lawrence of Arabia) fully captured at 6000 horizontal pixels (for a 65mm film)  Translates to 1470 for 16mm film − Could be less for reversal stock − And even less for telerecordings4-5 September 2012 Vietnam Film Institute Workshops 30
    31. 31. Bit Depth Dutch archive uses 10-bit log scale (which is what most equipment produces) Presto recommended at least 12 bits and preferably 14 bits, to capture the full range of film (number of “stops”) DFT scanner will capture 14 bits Kodak: “With the advent of KODAK VISION3 Color Negative Films, our motion picture films can capture up to 13 stops of scene content.” For colour, it is common to ADD the number of bits in each channel, and say “24-bit colour” – but the dynamic range is 8 bits, NOT 24 !!!
    32. 32. Bit Depth Examples 1, 2, 4 and 8 bit illustrations:http://en.wikipedia.org/wiki/List_of_monochrome_and_RGB_ palettes
    33. 33. 4-bit Linear vs 3-bit Log 4 bit linear = 16 steps 3 bit linear, same size steps 3 bit linear, each step twice as big 3 bit log scale, steps start small and get bigger4-5 September 2012 Vietnam Film Institute Workshops 33
    34. 34. Digital Formats for Film DPX uncompressed, very flexible DCI DCDM = Digital Cinema Distribution Master: 2048x1080 (or 4096x2160) only DCP = Digital Cinema Packaging = lossy compressed JPEG200; (not for master) JPEG2000 (lossless); 2:1 data reduction Various lossy compression formats (avoid!) And … various wrappers: MXF, AVI ...
    35. 35. Discussion Who is doing digitisation? What formats? What equipment? What results? What problems?
    36. 36. Tea Time Next: Digital Preservation Strategy Format Roadmap Digital Storage Technology Estimating Costs Building a Business Case Digital Format Roadmap

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