Let’s emulate the sound of colours!

Collaboration

Very little of the available technology and tools have been designed and manufactured especially for audio-visual archiving purposes. On the contrary, most of the technology and tools, that we are using in our daily archival work, have actually been designed and developed for today’s production and post-production needs. We as archivists, conservators and restorers are continuously adapting this technology and tools to fulfil our specific preservation and access needs. Therefore we only rarely have for example a carbon arc projection of a toned and stencilled nitrate print, but usually we will enjoy a modern digital projection, that emulates as best as possible that specific historic look through a file.

Emulation can, of course, also be seen in a pedagogic sense: a master teaching to his disciples. And this is indeed important!

I entered this field in late October 1986. During these 30 years I have had the pleasure to meet many individuals who have been fundamental in developing my own career.

before

I like to thank warmly all who have been most crucial for my own professional development.

The work of the teams I have had the privilege to lead has always been a collaborative work. And this is true also for my own work! Collaboration on different levels: between institutions, between individuals, between companies; between institutions and/or individuals and/or companies.

Analogue and digital

In the late 1980s and the early 1990s, when I started considering digital methods for both film restoration and audio-visual conservation, I was mainly considered as a fool – or at best a candid dreamer. Many years after, before the end of 2013, when I closed down our photo-chemical laboratory, I was often considered as a person who missed the boat in the switch to the new digital world, because sometimes I still preferred to apply the «good old» analogue, photo-chemical methods. So goes the world… In fact I always tried to use the potentiality offered by both worlds and to mix them together, in order to achieve the best possible result, to have the most historically accurate presentation of a masterpiece or a document in the modern screening context. The penultimate job my photo-chemical lab did was the preservation of amateur films shot on Kodachrome film stock. Normally we used for this work Fujifilm daylight 64 ASA camera negative as an intermediate film stock because of its quality in analogue colour reproduction I felt was the best possible. Sadly by then it was no longer manufactured and we used the very last reels stored in our refrigerator.

The Joint Technical Symposium’s audience is a very special one, because, as its name says, this is a symposium of technically interested individuals that crosses over specialisations.

The people from the sound area moved first and quicker from analogue to digital, also because the relatively small size of data files made it a possibility much earlier. Yet sound people were in general less carrier fetishists than film people. I have the impression that the move from analogue mechanical recording to analogue magnetic recording, to digital magnetic recording, to file-based recording was more natural and less polemic in the sound fields.

The broadcast community shifted to digital just after the sound people, in order to take advantage of the digital possibilities for production and post-production, sometimes forgetting or ignoring the new challenges for the preservation, and almost always forgetting that restoration and enhancement are two completely distinct activities. I am not saying that one is superior than the other, I am simply saying that they are fundamentally different.

The film people are still in the middle of paranoiac contradictions. It seems to me that they use the most of their energy, time and money by continuing to restore again and again a few dozen of films they call canon. Some of the film people think that even digital-born films should be preserved onto film stock. Yet in today’s worst/best scenario we can record onto film only 1/64 of the image quality there actually is in the file. That’s less than 2% or, said in another way, more than 98% of the data is just good for… the rubbish bin. This situation comes from the fact that the camera sensors are constantly improving, but not the re-recorders onto film, as the market for this specific type of equipment is gone.

If analogue storage is the answer to all audio-visual preservation needs, why do we have to struggle that much with analogue conservation and restoration issues?

Standardisation

To follow standards makes an effective collaboration possible. I wish to illustrate this with three examples regarding file formats, that may be relevant to our field.

ProRes, often hated by archivists, because it’s a proprietary format of Apple. Yet this is a de facto standard in post-production. SMPTE (Society of Motion Picture & Television Engineers) wishes to standardise it. I don’t know for sure if this is «only» Apple ProRes 422 HQ is meant to be standardised, or also other flavours like 4444 XQ. I hope this time they will do a good job, avoiding the mistakes they made with the standardisation of the CineForm or VC-5 codec. Essential information is still keep secret by GoPro, and not all metadata described in the standard does actually match the metadata generated by… GoPro’s own products. An unfortunate situation indeed!

A group of scholars from the University of Basel in Switzerland has the goal to define a TIFF flavour coming with all the technical metadata that is relevant for preservation. Adobe having refused the name TIFF/A, as analogous to PDF/A, the group has chosen to name the new file format TI/A (Tagged Image for Archival). ISO (International Organisation for Standardisation) is the body where this new recommendation should be submitted, possibly amended, accepted and finally published.

The IETF (Internet Engineering Task Force) has established a workgroup called Cellar (Codec Encoding for Lossless Archiving and Real-time Transmission). Cellar is currently standardising the lossless video codec FFV1, the lossless audio codec FLAC and the extensible media container Matroska, which is based on EBML (Extensible Binary Meta Language), a binary XML format. Once adopted, these standards could also be submitted through ISO and SMPTE for additional validation.

Open Source Software

Today there exists plenty of open source software options which do not need one to be an engineer to use them. These form a complete eco-system for archival purposes. Here are my favourites:

FFmpeg is a complete, cross-platform solution to record, convert and stream audio and video. In my opinion, every audio-visual archivist should be literate in FFmpeg.

QCTools offers an extremely wide range of strong quality control tools for video preservation, developed by the Bay Area Video Coalition and Dave Rice.

I imagine you all are familiar with MediaInfo. MediaArea is currently developing the new tool MediaConch. This consists of an implementation checker, policy checker, reporter and fixer that targets preservation-level audio-visual files (specifically Matroska, LPCM (Linear Pulse-Code Modulation) and FFV1) for use in memory institutions.

The DCP has replaced prints in commercial film distribution for theatrical projection. DCP is a strange object, designed by the film industry to make film archivists’ lives more difficult. However, the archive can also consider DCP in its own agenda. Never before has an audio-visual archivist had a greater control over the manner in which the audience sees a historic film. The archivist can encode the right colours, the correct aspect ratio, an adequate projection speed… and the DCP will be screened that way in all cinema theatres worldwide. OpenDCP and DCP-o-matic are two of the tools allowing this.

Open Source Hardware?

In the analogue world things may appear simple. This is the minimal equipment needed to create the illusion of movement:

before

The minimal equipment needed to see the images of a silent 9.5 mm film in movement.
(This format is also called
Pathé Baby.)

In the digital world equipment with that simplicity is not available, so far.

When we built our first scanner, twelve years ago, we only modified one camera part of an optical step printer and retained all the other components – including the projector part, the lenses, the pre-wet device we developed and the mechanical movement – unchanged. The optical camera number 128 from Richard Craß in Berlin was the first one we have converted from analogue to digital. Many others made similar conversions.

You can also build in your kitchen a relatively simple machine for cleaning magnetic tapes of all kinds.

For archiving large amounts of audio-visual data often LTO is chosen. The magnetic tape based solution LTO (Linear Tape-Open) with LTST (Linear Tape File System) is indeed a good solution for data archiving in the real world. I do not think the archival world needs an open source LTO player now.

Conservation

In short, analogue conservation focuses on the chemistry of the base and the emulsion or the magnetic coating, and concludes that one should store materials in a cool and dry environment.

In a very short form, digital conservation concludes that one should keep every single bit unchanged, and focuses on the container, codes and the so called «raw» data.

I will spend a few words on migration. From January to June 2014 we have migrated the digital archive of our company from LTO-4 to LTO-6. I decided to also change some file formats and to convert them en passant into others, more robust for the future. We started with roughly 1000 tapes and ended up with less than 300 tapes. Yes, we reduced the storage volume in the security cabinet by more than two thirds, and have now even more consistent data. We have migrated 5.7 PB of data and encountered one single error, which we could fix by using the second back-up copy we had.

This kind of work must be done in an automated way, otherwise the so called «human error» factor became too important. Yet archivists need to be skilled in technical issues too, in order to be able to read critically the technical information provided by the industry and choose the solution that best fits the purpose.

Restoration

I have spoken many times about the ethics of conservation and restoration in my life (in 2010 I organised a full conference on this very topic). As I am becoming older, I more and more agree with the definition: «Restoration consists of replicating the errors of the past.» We as a professional community should be able to do more in our restoration work than just replicate the errors of the past.

The first software for digital image restoration essentially selected the region where a problem occurs, called ROI (region of interest), and they defocussed it a little, so the problem became less visible. In order to mask the fact that it’s less sharp, they increased the contrast a little, and the spectator has the illusion that the problem is solved.

More modern software does the work on the pixel level. They try to fix the actual problem that a pixel has, or that a small group of pixels have, and not longer to mask it. The newer programmes are more complex and need more powerful computers for efficiency. As restorers we can also use plenty of tools developed mainly by the game industry for special effects. If we use them cum grano salis, then we can actually perform true restoration work and not just simplify camouflage the existence of a problem. Of course, all these interventions have to be carefully documented, which is a difficult yet necessary task.

Recent developments

Very important advances have been made in the audio-visual and game industry.

The high dynamic range allows the archive to have a more accurate colour reproduction (for example of Dufaycolor, Kodachrome or Technicolor), and can be used to improve audio-visual archiving.

The high frame rate allows the archive to better encode the frame rates of the silent area and by multiplying frames and adding black frames, in order to emulate the projector shutter blades, gives a more accurate and also a more pleasant viewing experience. Theatrical access is improved dramatically.

Forensic science developed new tools, allowing us to read all the information out of a magnetic tape, and to interpret it by software.

The algorithms developed for DNA sequencing can be used to process the optical sound track from an archival scan, which should be done frame by frame and edge to edge, with a little vertical over-scan. This opens the most doors for further restoration work and post-production for diffusion and access. This way both conservation and restoration are improved.

 

Summa summarum: Let’s emulate the sound of colours from the past the best way the available techniques allows us to do today, by strictly keeping open all the possibilities for our successors. They must be free able to debate, modify and improve our own work.

Reto Kromer


I wish to acknowledge the help provided by Adrian Wood.


2016-07-11