Propositions for analogue archiving of feature films on 35 mm film

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The future of our history is now !

by Gilles Bissot

filmik

Distribution and presentation of feature films will very soon become completely digital. Final distribution masters will therefore not be made in the form of film, but by virtual and digital means. Because of this (r)evolution we have to start thinking about how films will be archived, as well as the costs of the different archival possible methods. A recent international symposium organized by the Cinemathèque françaiseon the subject :

“The digital revolution : what would happen if the movies lost their memory ?” (http://www.cinematheque.fr/fr/musee-collections/actualite-collections/actualite-patrimoniale/compte-rendu-colloque-numerique.html) conclude about conservation of the movies : “Today the film appears to be the only guarantee for long term conservation at a reasonable cost.” Similarly, during the same event, Laurent Cornier, director of cinematographic heritage at the CNC, gave the assurance that “legal deposition compulsory, according to the law of 1992, would continue to be done on film as well as by digital means.”

We have been thinking about this problem for several months now, with as starting point the idea that a movie consists of images as well as sound; we are of the opinion that we have to find a way to integrate sound and picture in an archive format on celluloid film. We have also attempted to formulate optimal costs of such archive storage on film. In fact, the color separation necessary to store color pictures on black-and-white film would, unfortunately, for reasons of durability, multiply the length of the film by three. If you add sound to that, the length has to be multiplied by four, which then makes it very expensive. With this in mind, we would like to put forward different suggestions for possible formats for the archiving of sound and picture on 35mm film :

I. 1) Film recording of the pictures on a color intermediate negative with a classical sound negative, which offer the possibility of printing 35 mm copies. This can be very interesting in case of distribution on the international market, particularly in countries that are not equipped with digital projection yet.

2) This intermediate color negative may also contain the 6 tracks uncompressed sound in the unused area of the inter-frame zone (see illustration on page 2). Pictures in 2,39:1 scope format have to be recorded “flat”, which means unsqueezed.

II. 1) 2) 3) Color separation masters on black and white intermediate negative, with 4, 3 or 2 perforations per frame, depending on the aspect ratio of the pictures (from 4:3 to 2,39:1). The purpose is to optimize the length of film, and so reduce the cost, by rationalizing the surface of film being used. We also propose to add the uncompressed 6 tracks sound master 24 bits 48 Khz on the same negative, by adding a fourth picture containing the digital sound converted into a 2D barcode in an open format such as QR code.

II. 4) An archival format in B&W separation mode at a very affordable cost, but possible only for 2K : we propose to record a single 4K composited picture made from the 3 RGB 2K channels and the 6 tracks of digital sound in QR code (see illustration on page 4).

I. Archiving & film distribution : Recording on color film stock

=> Life span expectancy of 100 years (*)

1) Recording on color intermediate stock + Dolby optical sound negative :

Possibility of making distribution color prints

  • 2K or 4K recording of the pictures on a 35 mm polyester based color intermediate negative film stock in 4:3, 1,66:1, 1,85:1 or 2,39:1 anamorphic – 4 perfs/frame.
  • Encoding 5.1 sound final mix in Dolby SR and/or SRD.
  • Optical sound negative recording of the Dolby SRD and/or SR sound.
  • Printing of a 35 mm positive checkprint with sound, for verification and color reference.
  • Possibility of making 35 mm distribution prints.

=> Storage of 5 reels of picture negative + 5 reels of sound negative + 5 reels of positive reference print. Total = 15 cans of 610 m (duration between 90 and 100 min.)

2) Recording of pictures and uncompressed sound on color intermediate stock :

Possibility of making distribution color prints (1,85:1 only)

  • 2K or 4K recording of the pictures on a 35 mm polyester based color intermediate negative film stock in 1,85:1 or 2,39:1 “flat” (without squeeze) – 4 perfs/frame.
  • 6 tracks digital uncompressed sound is split frame by frame. Each 1/24th of a second of each track is converted into an open source matrix barcode format such as QR code, which takes place above and below picture (see illustration below).
  • Optional making of a Dolby optical sound negative with Dolby SRD and/or SR sound.
  • Printing of a 35 mm positive checkprint with or without sound for verification.
  • Possibility of making 35 mm distribution prints (if optical sound negative – 1,85:1 only).

=> Storage of 5 reels of color negative which contains 2K or 4K images and the 6 tracks of uncompressed sound. Total = 5 cans of 610 m.

 

archive coul 2K-ok

 

II. Archiving only : Recording on B&W intermediate film stock

=> Life span expectancy of 500 years (*)

1) Recording of picture separation master and 6 tracks uncompressed sound :

All image format => 4 perfs/frame = 4 times the length of the film

  • All image aspect ratio possible, from 4:3 to 2,39:1 anamorphic – 4 perfs/frame.
  • 2K or 4K sequential recording of the RGB separation on B&W intermediate film stock.
  • 6 tracks digital uncompressed sound is split frame by frame. Each 1/24th of a second of each track is converted into a 2D barcode in an open format such as QR code, which is added as a fourth picture.

=> Storage of 20 reels of B&W film stock containing both 2K or 4K picture and 6 tracks of uncompressed sound master. Total = 20 cans of 610 m.

2) 1,85:1 image – Sequential RGB recording 3 perfs + 6 tracks uncompressed sound

  • 1,85:1 aspect ratio only – 3 perfs/frame.
  • 2K or 4K sequential recording of the RGB separation made from the color picture on B&W intermediate film stock.
  • 6 tracks digital uncompressed sound is split frame by frame. Each 1/24th of a second of each track is converted into a 2D barcode in an open format such as QR code, which is added as a fourth picture.

=> Storage of 15 reels of B&W film stock containing both 2K or 4K picture and 6 tracks of uncompressed sound master. Total = 15 cans of 610 m.

3) 2,39:1 image – Sequential RGB recording 2 perfs + 6 tracks uncompressed sound

  • 2,39:1 aspect ratio only – 2 perfs/frame.
  • 2K or 4K sequential recording of the RGB separation made from the color picture on B&W intermediate film stock.
  • 6 tracks digital uncompressed sound is split frame by frame. Each 1/24th of a second of each track is converted into an open source matrix barcode format such as QR code, which is added as a fourth picture.

=> Storage of 10 reels of B&W film stock containing both 2K or 4K picture and 6 tracks of uncompressed sound master. Total = 10 cans of 610 m.

4) 2K image – Recording of a 4K composite 4 perfs + 6 tracks uncompressed sound

  • Image aspect ratio possible from 1,66:1 to 2,39:1 – 4 perfs/frame.
  • Recording of a 4K composite picture made from the 3 RGB channels of the 2K color image, on B&W intermediate film stock.
  • 6 tracks digital uncompressed sound is split frame by frame. Each 1/24th of a second of each track is converted into an open source matrix barcode format such as QR code, which takes place around the composited RGB picture (see illustration on next page).

=> Storage of 5 reels of B&W film stock containing both 2K picture and 6 tracks of uncompressed sound master. Total = 5 cans of 610 m.

(*) Estimations made by FUJIFILM for ETERNA-RDI (color) and ETERNA-RDS (B&W) polyester-based film stocks stored under standardized appropriate conditions at 15°C with 30-40 % RH.

RDS_2K RGB in 4K-2

III. Conclusion

All the solutions explained above are possible. We explain all of them because none of them have all the advantages. Some of it are still under development or being tested. The idea leading our researches is to offer the best solution for everyone, with the best compromise between quality, price and lifespan depending on many production parameters : budget, resolution, image format…

Any observation, question or reaction on the subject is welcome !

Gilles BISSOT FilmiK Film Recording feb. 2012 (DRAFT)

info@filmik.be

www.filmik.be