The film FOCUS is a black and white movie with a magnetic sound track recorded at 16 frames per second. A screening of this film, lasting 10 minutes, comprises the first part of the paper.
The prints from the original are processed to give black lines on a white (clear) background purely as a matter of taste. Whilst scratches made by badly adjusted projectors are more noticeable, commercial scratch treatment is very effective on this type of print. This is because the processes restore the base material and emulsion as regards their transmission of light but cannot, of course, selectively redeposit silver. In connection with scratching, it has been found useful to remove a small almost superfluous guide-plate on our BD 644 Bell and Howell projector. This enables the sound drum to be bypassed. The high inertia of this makes it continue running after the film has stopped. Although the drum appears smooth it does cause scratching with start-stop running.
The object of making FOCUS was to illustrate the software available and to gain first-hand knowledge of the snags as well as the possibilities afforded by the film industry. A suitable area offering experience of both proved to be that of sound-effects.
After a reasonable print of the film had been obtained, I then began to consider the details involved in the addition of a sound-track to the film. Since 16 frames per second is equivalent to almost 5 inches per second and because computing requirements are high for animated movies, I had decided to record sound at the so-called silent speed. I did not envisage producing many very high audio frequencies in the sound-effects. As far as the film industry was concerned, however, I had already committed the sin of going to a non-standard or rather, unheard-of, sound speed. After a brief consultation with the men in the film laboratory's sound department, I was instructed to supply them with an ordinary (!) tape recording, perfectly sound balanced for volume and exactly matching the film in timing. They would then be able to transfer this to a perforated 16 mm magnetic tape running at 24 frames per second - their only speed. Although unable to monitor it they would end up with a master recording ready for either transferring to a magnetic stripe added to a print, or for producing a photographic or optical sound track also for transferring to a print. As the 16 mm magnetic tape is perforated the same as the film, the sound-track once correctly recorded on this then presents no synchronisation problems in transferring to a print.
I now understand the mechanics of actually obtaining a sound-track on the film, but all the difficulties of generating sounds and achieving synchronisation lay ahead. Fortunately, help was to hand: a professional film maker, Peter Hadingham of Swift Film Productions who once made a documentary film about our Laboratory was easily persuaded to become involved in a computer animated movie. He protested somewhat at recording sound at 16 frames per second but said that he could do it. The aim was still to generate a perforated 16 mm magnetic tape as a master for subsequent transfer to a striped print(s).
The first task before going to the studio was to produce a script for the dialogue and notes as to the sound-effects for the other sequences. Even though it was not possible to decide on all the sounds until the very last moment, the majority were noted down at an early stage. In the case of the dialogue, the object was to express the basic principles concisely about what was being shown, with regard for accuracy and with little or no ambiguity. A Bell and Howell projector with helper proved invaluable in the final stages of rewording the script to fit more exactly with the pictures. Sequences were lengthened in order to get all the relevant details in, as well as producing a more smoothly flowing visual presentation.
The actual production and recording of the sound effects and dialogue were virtually completed in one very full working day by Peter Hadingham and myself. I arrived imagining that the sounds I had requested would be gradually produced one by one from a library of records. It was soon pointed out to me that unfortunately even if just the right sounds could be found, copyright fees payable would add considerably to the cost.
The method of recording was to employ a modified Bell and Howell model 640 projector. It has been adapted to run double-headed i.e. to transport a 16 mm perforated magnetic tape as well as the film being projected. Basically, two extra spools had been mounted so that both film and magnetic tape could be taken up. If desired, the projector could be restored to its original state with no marks showing. The projector's magnetic head could also be manually moved in and out of play/record positions. This eliminated noise in going from play-back to record whilst projecting and thus permitted a high degree of synchronisation.
The sound effects were initially recorded on the tape recorder which had a mechanism on the tape-deck preventing switching-on noises being picked up by the recorder. These effects were then transferred to the projector with both film and perforated magnetic tape running through. For merging sounds it was necessary to employ two tape recorders. A third portable recorder proved useful for recording sounds that had to be generated outside the studio itself, such as the sound of running water used in one sequence.
Another factor that I had not appreciated was the high degree of synchronisation necessary between the start or finish of a sound with the projected image. To achieve this it was necessary for one of us to operate the projector, whilst the other started the tape recorder used for storing the sound effects as we went along.
Thanks to the immense talent of my colleague both musical and for improvisation, sound production forged ahead at an incredible rate. Bongo music, either South American or Afro, zither music, xylophone, guitar, flute or bass fiddle sounds could be produced to order. I was even persuaded to contribute a grunt at one point! Some sounds, such as a cine-projector running when recorded from an actual machine, did rot sound anything like it: a hand-turned sewing machine made a much more realistic projector noise. A breeze turning into a gale can be nicely simulated by blowing into a microphone held close to the mouth. A large diameter film spool on a high speed rewind substitutes well enough for a jet plane, and may be recorded in more comfort than to attempt to capture a real one. Other sounds may be made more intriguing using faster playback before adding to the sound track. By taking the back from a cuckoo-clock the bird may be persuaded to call on demand at a rate to suit you.
After the 16 mm magnetic film had been satisfactorily recorded at 16 frames per second, a sprocketed tape recorder running at 24 frames per second and driven in synchronisation with the film projector was used to transfer the sound onto the film stripe. As the print had been made on single perforated stock it was possible to have a full-track magnetic stripe as opposed to a ¼-track one. This provides for more sound volume with less background noise if being shown to a large audience. The transfer is done each time a new copy of the film is produced requiring a sound track. It would be possible to convert the magnetic sound track into an optical one, but loss of quality would undoubtedly result at this projection speed.
Apart from the fact that a film recorded at 16 frames per second cannot be replayed on T.V. which in Britain runs at 25 frames per second, few drawbacks exist. Most projectors will play-back at 16 frames per second and with full-track striping results are more than reasonable.