DOLBY Sound - Overview

As of the end of 1991, over 3,300 Dolby Stereo films had been made in 31 languages. Of these 155 are available with Dolby Stereo SR optical soundtracks and 168 with 70mm Dolby Stereo magnetic soundtracks. There are now Dolby equipped studios in 27 countries set up to mix in the Dolby system, although not all of them are equipped to do SR and/or 70mm Dolby mixes. There are over 17,000 Dolby cinemas throughout the world, in more than 40 countries. Of these, about 2,700 are set up for Dolby SR. (These figures are very much of date now, of course).

In a nut shell, Dolby Stereo is 3 different systems of high-quality, multi-channel sound for the cinema. They are: the original DOLBY STEREO, the later improved DOLBY STEREO SR (Spectral Recording), and now DOLBY STEREO SRD (Spectral Recording Digital) with an added 6-channel digital sound track. A nice thing about the system is its universal compatibility. Any print of any of these Dolby systems can be played in any cinema, whether they are equipped with any one or none of the Dolby sound systems. So if a Dolby print goes to a cinema without a Dolby sound system, they can still screen it, only the sound wont be as exciting or dynamic. It will sound more like a regular optical stereo or mono track with a slightly compressed dynamic range. For example, Dolby Stereo SR prints still sound very good when reproduced in a conventional (A-Type) Dolby Stereo Cinema, and provide very acceptable results in a mono cinema (without any Dolby equipment). Of course, the full potential of a Dolby SR print will only be realized in a cinema with a SR processor, and Dolby SRD prints with a Dolby digital soundtrack adaptor, together, of course, with a good cinema sound and speaker system.

Dolby has managed to get the best of both worlds ... greatly improved sound quality together with all the practical and cost advantages of good old-fashioned optical soundtrack reproduction. What's more, it has become a world-wide industry standard recognized and accepted in most countries. The basis of the system is noise reduction, a system of audio compression and later decompression of the audio's dynamic range, like in familiar domestic sound equipment from walkmans to component stereos. This helps reduce the levels of unwanted background noise inherent in all magnetic and especially, photo/optical, recording systems. This is especially true with all the repeated copying that goes on in the post production of a film. In other words, less hiss and other glitches and blops. Dolby also manages to maintain a wide frequency response, partly by checking that certain standards are met during the mixing and sound neg. stages of post production. This means the production must hire a Dolby consultant, a requirement by Dolby Laboratories (more about this later). Dolby takes the process further with Dolby Spectral Recording (SR). It uses a newer signal processing system that gives even better quality, louder undistorted climaxes, and overall quieter backgrounds and cleaner sounds. Dolby Stereo SRD adds digital soundtracks for the highest quality sound with even better stereo and surround effects. But as I say, remarkably, any of these prints can be played in any cinema.

Another feature of the Dolby system is the so called, Centre Channel. It helps to localize sounds which should come from the central area of the screen, for those in the audience who are sitting away from the centre. As well, the surround speakers, not only produce special effects behind and to the sides of the audience, but also add depth to the sound which helps increase the audience involvement in the movie.

Quality control is part of the Dolby process. Dolby `forces' you (for your own good, of course) to maintain certain technical standards through out every stage of the film's post production. They assign a Dolby Sound Consultant to each film under a consultancy agreement. This guy/gal can discuss with the location sound recordist the proper recording techniques for Dolby Stereo. The consultant checks the studio's facilities are up to scratch. The consultant is usually present for all or part of the mix, according to the experience of the particular studio and if you need them there or not. The consultant's role is meant to be purely technical, and is not meant to influence creative or stylistic aspects of the mix. The consultant can also assist with the mixing of the music for the film, to ensure, for example, that it is monitored via a Dolby Stereo encoder and decoder, so the music is heard as it will be heard later in the cinema. The Dolby Sound Consultant will also carry out print checks where necessary to see that the sound neg. and final lab work was done correctly, or check out a cinema's installation for special preview screening, designed as a final technical check on everything including the sound.

A licensing agreement must be entered into before the mix starts (or preferably much earlier). There are two agreements to be signed by the production company/producers in connection with the use of Dolby Stereo. One licenses the use of the Dolby trademark, and lucky us, this costs nothing. It is called The Trademark and Standardization Agreement (Motion Picture Soundtracks). The other agreement covers the `compulsory' consultancy service and the use of special equipment. It is called The Motion Picture Service Agreement (MPSA) and a sample copy is enclosed (designed for Europe). The MPSA, together with a fee, covers both the use of special encoding equipment at the approved studio, and the services of the consultant at key stages of the production. Separate fees are payable for foreign language versions where M & E mixes are necessary. Any additional charges are detailed in the MPSA, and apart from that, there should be no further charges to be paid (unless extra consultancy time is specifically requested).

So what about these charges? To give you an idea of the bottom line ... feature films (with a running time of over 45 minutes) have a basic cost of Ł2,900 (approx 8,700 marks, or less if the pound is down). This gives you the services of a Sound Consultant for 16 hours during normal working hours. Fortunately, there is a Dolby Sound Consultant in Berlin and don't need to pay travel, meals and accommodation costs like we do in Holland. Additional time for a Consultant will cost Ł30 per hour (or Ł45 per over-time hour) with a 3 hour minimum per call. The cost of shorter films up to 45 minutes is Ł1,450. Even shorter films are calculated at Ł75 per minute up to 20 minutes in length. Payment of the fixed services and equipment Fee is supposed to be paid before the start of the mix. The other costs as they arise.

The company, quite wisely, advises you to start thinking and planning around Dolby Stereo before the start of the production, or as early as possible, particularly for the more exacting Dolby SR system. Just prior to mixing is the last possible time to negotiate a Dolby Stereo agreement. Badly recorded sound can not be later upgraded by any Dolby system, so the emphasis, as always, is to strive for the best possible sound quality throughout the production/post production cycle. One of the main function of the Dolby system is to help preserve this quality. Sub-standard recordings will not only sound bad, but will tend to stand out later on. This happens when they are mixed with other high-quality sounds in post production, which makes the inferior recordings (including older-type library material) to sound even worse than it is already.

It is best to start using Dolby Noise Reduction from the outset. The location recordist should use Dolby SR, or at least, Dolby Type-A, noise reduction for analogue tracks to improve overall background noise and distortion levels. Dolby Noise Reduction (NR) exists in two professional forms: A-Type, the original industry standard for sound and film recording; and Dolby Spectral Recording (SR), which provides even more powerful noise reduction processing, and also reduces distortion. Dolby SR provides greater noise reduction than A-Type and makes a dramatic reduction in modulation noise. Signal handling is improved at very low and very high frequencies and there is a reduction in distortion across the whole frequency range. The overall result is a much purer sound quality. With optical soundtracks, SR deals remarkably well with medium and low-level noise introduced by dirt and wear on film prints. In the cinema, the latest Dolby cinema processors are equipped for both SR and A-Type signal processing. Existing Dolby Stereo A-Type cinema processors can be fitted with an adaptor for SR encoded prints, allowing easy switching between the two systems. The original Dolby A-Type NR has been used world-wide in music recording studios. Now Dolby SR is installed in many of these studios, as well as film, radio and T.V. studios. The basic idea of NR is to protect the various sound tracks over the many generations required in a film's lengthy post production. Without NR, soundtracks soon become seriously degraded as they are repeatedly copied. The sooner NR is introduced (e.g. on location sound recording), the better the final result.

Here is a rough schedule for using Dolby Stereo. Start preliminary arrangements with Dolby during pre-production. On the set, all analogue recordings should be made using one or other NR system, preferably Dolby SR noise reduction. Dialogue tracks should be recorded in mono, and not stereo as one might expect. `Panning' can be used in the mix to position dialogue where ever it is appropriate. Atmosphere tracks, on the other hand, are better recorded in stereo, if possible. However, enough mono atmosphere should be recorded specifically for use as fill in the later editing of the mono dialogue tracks. If not used earlier, you should now start using Dolby NR when transferring location sound to 35mm or 17.5mm magnetic film (perfo) or multitrack recorder. Calibration tones and pink noise should be recorded at the beginning of all tracks. The tone enables levels to be checked that ensure the correct operation of the noise reduction system, and the pink noise enables azimuth and frequency response checks to be made. During track laying, older-type library sounds and effects, should be avoided if they are not comparable in quality to the rest of the sound track. It is best if library sounds effects and atmospheres are in stereo. Preferably use C.D.s as the source of library sound material. Last chance to enter a license agreement with Dolby Laboratories before mixing starts. During the mix, the use of the special Dolby Stereo 4-channel analogue matrix encoder/decoder (DS4E DOLBY STEREO ENCODER/DECODER), under the supervision of the Sound Consultant, is essential for listening to the four-channel mix, in order to simulate the final cinema sound. The final stereo magnetic master of the mix must be Dolby encoded ready for transfer to optical. The Dolby consultant will check the test signals and compare the first optical print with the Dolby Stereo magnetic master. Cinemas elected for special previews can be checked and realigned if necessary.

In terms of Dolby equipped studios in Europe. There is one in Holland, namely, Meta Sound. The nearest Dolby Consultant must come from England, however. Berlin is much better. It has a Dolby Consultant and 6 recognized studios if you include Babelsberg Studios in Potsdam. Elsewhere in Germany: 5 studios in Munich, 3 in Hamburg, and one in Dortmund (15 in total!). The U.K. has 11 studios, Belgium has 2, France 9, Italy 10, Spain 9, Switzerland 1, Sweden 4, Denmark 1, Norway 1, and Finland 1. Mosfilm in Moscow has a Dolby equipped studio, and probably unbeatable prices. Also, there is another studio in Prague.

In terms of optical transfer facilities to make the Dolby sound negative, there is fewer of these. There is 1 in Prague, 4 in France, 4 in Germany (2 in Berlin and one in each of Munich and Hamburg), 3 in Spain, 2 in Sweden, 4 in the U.K.,and 1 in Switzerland. Holland probably sends theirs to be done in England seeing they hate all their immediate neighbours.

If you want more details, write to Dolby at their European headquarters at the following address: MAGGIE LONGMORE (Film Projects Co-ordinator), DOLBY LABORATORIES INC., WOOTTON BASSETT, WILTSHIRE SN4 8QJ, UNITED KINGDOM. Telephone: (44) 793-84 21 00 or Fax: (44) 793-84 21 01 or Telex: 44849. Maggie might want to know where you expect to do the mix ... just tell her Geyer in Berlin. Anyway, they'll send you all the stuff. Don't forget to ask for the "Producing a Dolby Stereo Soundtrack" booklet, but it should be included. You could also contact one of the Dolby Equipped studios in Berlin like ARRI CONTRAST (Tele: 300-09 10), BERLINER SYNCHRON GmbH (Tele: 77-50 41), BERLINER UNION FILM GmbH (Tele: 759-42 80), GEYER SYNCHRON GmbH (Tele: 680-13 11 or 680-13 12), or MICHAEL EILER FILMTECHNIK (Tele: 300-09 20 or 304-59 66).

Peter Gray
(near Los Angeles)
P.O. Box 5132
Pine Mountain Club, CA 93222
United States of America
telephone: +1(661) 242-1234

dp@petergray.org