FR2691005A1 - Recording and reproduction of images, digital sound and analog sound on photochemical film. - Google Patents

Abstract

The technical field of the invention relates to the cinematographical, telecinematographical and audivisual industries. The invention provides for recording and reproducing, on the same compatible photochemical film medium, images (1) recorded on two perforations and running at the rate of 48 to 50 images per second, auxiliary digital tracks (2) and (3), main digital tracks 94) and analog tracks (5). The shoting framing format of approximately 1/2.00 (10) provides for use of the film in a format of 1/1.77 (7) format 1/2.35 (8), including the 1/2.00 format (4).

Description

Recording and reproduction of images. digital sound and sound
analog on photochemical film
The technical field of the invention relates to the cinematographic, tele-cinematographic and audiovisual industries.

INDICATION OF THE CURRENT STATE OF THE ART
The global film industry is dominated by the use of more than 90% positive or negative 35 mm photochemical film.

 It should be noted that 35 mm negative films used for recording images or sound have a lower definition than the positive film used for image and sound reproduction. At projection, the grain of the negative will appear first.

Despite everything, it can be seen that the image recording negatives are sometimes produced in a surface format smaller than the format of the image reproduction positive.

example 16 mm super negative -> 35 mm positive 35 mm negative -> 70 mm positive
Worldwide. it can be seen that more than 90% of the films screened in cinemas use the positive 35 mm film, which makes it the international standard for exploitation.

 Projection in a 70 mm positive film room is marginal because it is too expensive and generally not compatible with other projectors fitted to the same multi-room complex.

 The projection in a 16mm positive film room has been replaced by the better 35mm for a similar operating cost. 16mm is therefore often used for recording super 16mm negative films (intended for television productions). which are reproduced on 35 mm positive if it is necessary to use them in a cinema.

 As we can see, the 35mm standard is firmly rooted, due to the many technical and economic imperatives that justify its supremacy.

 It has recently been designated as the best image recording medium for tomorrow's high-definition TV productions.

THE NEW OPERATING CONCEPT
35mm shows its limits in the new forms of cinema operating.

Indeed, theatrical exhibition being more and more competed by television, cinema professionals are moving towards a new form of spectacular projection based on the "giant" screen, (80 and 230 m2) r and high quality sound to attract audiences
For the reasons we have mentioned above, these new rooms use more than 90% of 35 mm positive film. As a result, if the 35 mm projection on screens up to 80 mZ of surface offers a satisfactory image quality, the new screens beyond 80 mz offer a decreasing image quality often proportional to the increase in their surface.

The sound of the standard 35mm analog does not offer the quality that the public finds at home on compact discs.

 These disappointing results are due to several technical factors * For the image: the subjective quality of the image depends on four main factors 1 - the definition of the film: which corresponds to the surface used per second 2 - the number of images per second (strobe effect factor) 3 - the number of shutters per second: (flicker factor) 4 - the light output of the projection on which the contrast and color quality depend: it depends on the previous parameters and performance of the projector used.

If the subjective quality is almost always satisfactory for screens less than 100 m2, that of so-called "giant" screens of more than 100 mz is often poor for several reasons.
1 - The definition of the film which corresponds to the surface used per second, is used for example for the 1 / 1.85 format only at 60% of the available useful surface. For the 1 / 2.35 format, the surface which is 100% used this time results in a loss of definition due to the anamorphic process it uses,
2 - The number of images per second (24) is not sufficient and the strobe effects become very visible even for slow movements when the screen is around 160 m2. This causes additional eye strain for the viewer.

 3 - The number of shutters per second (48) is not sufficient because the flicker disappears at 60 shutters per second, (for shutter times of approximately 50% of the total time). It also causes eyestrain for the viewer.

 4 - The brightness of the projection is penalized by a loss of about 50% of the light emitted by the light source during the shutter times necessary for moving the film. The most powerful light sources for 35 mm reach 7000 watts and are barely sufficient for surfaces up to 160 m2.

t For sound: 35mm is analog. Its bandwidth in the best of cases does not exceed 12.5 KHz. Noise reducers remain
Dolby A and Dolby SR, (registered trademarks), commonly used, very sensitive to dust and scratches inevitable in the life of a film in exploitation.

Sound performance in theaters is unfortunately very dependent on the film production process and the quality of the projection system's playback system.

Here too, the results are too often disappointing for the public who have become used to digital sound, the reliability of analog optical sound being poor.

Despite the growing public demand for cinematographic spectacle on a giant screen, the shortcomings of the current 35 mm recording standard are intolerable in the face of the arrival of high definition technologies for television and digital sound on compact disc and soon DCC, ( Digital
Compact Cassette).

PROPOSED IMPROVEMENTS FROM THE 50S TO TODAY
A - 70 min. 6 magnetic tracks, 24 and 30 images / second
B - 70 mm Show Scan
C - 70 mm 15 Imax / Omnimax perforations
D - 70 mm 6 Kodak / ORC digital tracks
E - 35 mm digital Kodak / ORC
F - 35 mm SRD Dolby
A 1 - The 70 mm 6 magnetic tracks 5 perforations, 24 images / second and 48 shutters / second.

Created in the 1950s, the 70 mm 6 magnetic tracks provides an improvement for the definition of the film (larger surface per second). The other three image parameters remain unchanged. The quality of the 6-track magnetic sound also justified its survival despite its non-compatibility with most installations.

A 2 - The 70 mm 6 magnetic tracks 5 perforations, 30 images / second and 60 shutters / second.

It improves the definition and the flicker. It was quickly abandoned because it was too expensive and totally incompatible.

B - The 70 mm Showscan, (registered trademark). 6 magnetic tracks 5 perforations, 60 images / second and 60 shutters / second.

Created in the USA in the 80s. For screens up to 220 m2. it has an excellent definition, the strobe effects are not visible and the flicker is no longer perceptible. It would make it possible to produce screens of 400 ion2, but the 60 closures per second not making it possible to improve the light output of the projector, (which is always approximately equal to 50%) this is not possible.

Its main defect is that it is totally incompatible and of an excessively high operating cost, in particular due to analog magnetic tracks, (approximately 20 times the cost of exp] oitation of 35 mm). For these reasons, no feature film has not been done, (despite the very good subjective quality it offers).

C - The 70 mm Imax / Omnimax, (registered trademarks), 15 perforations, 24 images per second and 48 shutters per second. Magnetic sound tracks on separate support.

It improves definition per second. The very large area of film used makes it possible to produce screens of 600 m2. The flickering and strobe effects due to the low number of images and shutters make the projections very tiring.

For these reasons, no feature film has been made. The sound 6 magnetic tracks' on separate tape makes it the most expensive system in operation.

D - The 70 mm 6 digital tracks 5 perforations, 24 images / second and 48 shutters / second.

Presented in 1990 by the Kodak and ORC Companies, i] does not offer any new solution for the image compared to the 70 mm 6 magnetic tracks 24 images / second and 48 shutters / second.

Its digital sound recording system is the subject of patent No. WO 91/05335 of 04/18/91. It is reliable and has characteristics similar to those of compact disc.

E - 35 mm 6 digital tracks 4 perforations, 24 images / second and 48 shutters / second. Produced by Kodak / ORC.

Presented in 1990 by the Kodak and ORC Companies, it does not present any new solution to improve the image of 35mm.

Its digital sound recording system is the subject of patent no WO 91/05335 of 04/18/91. It is reliable and has characteristics similar to those of compact disc.

To register the digital tracks, this method uses the traditional location of the analog optical track. For this reason, it is not compatible with other projectors in the same complex that do not have the necessary equipment.

F - 35 mm 6 digital tracks with 4 perforations, 24 images / second and 48 shutters / second presented in 1991 by the Dolby Company.

It does not offer any new solution to improve the image of 35mm.

This process uses the space left free between the perforations. It is compatible
because it preserves the traditional analog track.

The film having more wear between the perforations, the system
uses the information from the analog track as soon as the information
are no longer sufficient to reconstruct the signal.

For this reason, it is difficult to consider this technique as 100%
digital.

 The exploitation of this process should start in 1992.

CONCLUSION
This list is not exhaustive; we are only dedicated to
most innovative processes. Digital sound systems on supports
are numerous, but offer nothing to improve the image, and
entail servitudes and costs that cannot be envisaged in the large
exploitation.

For sound, in addition to the fact that it must be 100% digital and reliable, the
current systems offer no solution to be able to record
several languages simultaneously, (which would be of great interest because cinema
is an international industry).

Besides, there are and there have been many other ways
to record a film on cinematographic film. but none offers
to solve the problem as a whole. On the contrary,
current 35 mm image recordings, between 1 / 2.35 format and
1 / 1.37 further complicates the problems posed to the film industry.

The study of the current state of the art reveals the many shortcomings of the various standards, both in terms of image and sound.

However, it makes it possible to identify the 3 main categories of exploitation.

large screens from 20 mw to 80 m2. They represent the great
majority of screens and use the standard 35 mm.

2: Giant screens from 80 to 230 m2. They represent the trend of
new cinema concept. They mainly use 35 mm standart,
sometimes 70 mm 24 frames / second, and for a few rare operations
the Show Scan in short film.

3: Super giant screens, generally from 400 to 1000 m2. They use
only the Imax / Omnimax process reserved exclusively for the short
footage.

 Of the three categories, the first has satisfactory image quality.

 For category 2, the current 35mm offers an unsatisfactory solution.

the 70 mm 24 fps processes are subject to stroboscopic effects and
flicker.

The Show Scan process (which is also excellent for 230 m2 screens) is
far too high for the exploitation of feature films.

For category 3 of super giants, the] max / Omnimax process despite
higher operating costs, does not offer image quality
satisfactory, which confines it to the exploitation of short films.

STATEMENT OF THE INVENTION
The present invention allows the recording and reproduction on the same photochemical film medium of digital sound tracks, analog sound tracks and cinematographic images; by keeping compatibility with existing equipment, while improving overall image and sound reproduction performance.

 The current state of the art has shown us the various gaps in image and sound reproduction for screens up to 230 m 'from 35 mm film support.

 The invention makes it possible to globally remedy the various problems posed in cinematographic exploitation of 35 mm film.

- according to a first characteristic, it is compatible (image and sound)
- recording and reproduction of digital sound tracks
provides multiple languages. In addition, positioning
of these tracks in a place which undergoes few alterations in
operating allows high operating reliability.

- recording and reproduction at a rate of 48 to 50
images / second, (2 perforations per image in 35 mm), (96 to 100
fillings / second) allows
- to increase the surface used to
recording and reproduction, (in relation to the format
4 holes 1 / 1.85)
- reduce the strobe effects by a factor of 2
- cancel flicker effects
- to increase the possible light output, and by
consequently improve the quality of contrast and colors
of the projected image.

- according to a second characteristic, its cheese (1 / 2.00) will allow
operation on screens between the formats' f / 1.77 and 1 / 2.35.

The invention also enables television professionals
- have a 1 / 1.77 image high enough to
televisions 4/3.

- to have an image in format 1 / 1.77 equal to the format of the screens
HDTV 16/9.

- have 48 to 50 images / second which will allow better
image quality, for reproduction of works in High Television
Definition.

Figure 1/1 shows a 35mm film seen flat. With reference to this
drawing, we distinguish
- the location of the images recorded on 2 holes (1)
- the location of the auxiliary digital tracks (2) and (3)
- the location of the main digital tracks (4)
- the location of the analog tracks (5)
- the location of the surface corresponding to the recorded image (6). of a
format of approximately 1 / 2.00.

- the location of the surface usable for processing the image in format
1 / 1.77 (7)
- the location of the surface usable for processing the image in format
1 / 2.35 (8)
- the location of the surface usable for processing the image in format
1/2, .00 (9)
- the location of the framing surface in the viewfinder of the camera
of view (10), of a format of approximately 1 / 2.00.

DETAILED PRESENTATION
The new format works at 48 or 50 images / second for 2 perforations per image in 35 mm (See Fig. 1/1).

- It is compatible for image and sound, which is essential in the film industry, and especially the exploitation in multi-room complex.

- Indeed, a traditional projector 24 images / second and 4
perforations by image will project an image (1) on two, will be able to use
analog tracks (5), and can also play the sound track
digital (4) if equipped with digital player and decoder.

The subjective image quality will be satisfactory for screens ranging
up to 80 m2 in 1 / 2.00 format.

The only equipment necessary for the projection of this new format for
current projectors 24 frames / second, is the installation of a lens
and an additional projection window.

- If necessary, we can make operating copies
traditional 24 frames / second in 1 / 1.85 format for rooms that
are not equipped with the lens and the projection window
additional.

- The shooting of the new format will be done in 48 or 50 images / second on 35 mm film, at the rate of 2 perforations per image (1).

A modified 35 mm camera will be necessary for recording images on 2 holes.

A modified cinema projector will be necessary for the projection of the new format at 48 or 50 images / second. Its main features will be
- playback of auxiliary digital tracks (2) and (3)
- sound playback digital track (5) and analog track (4)
- 48 or 50 images per second on 2 perforations in 35 mm
- 96 to 100 shutters per second
- 1 lens is necessary
Thanks to this new format, the subjective image quality will be higher than the old 35 mm standard (with equivalent screen area); this for the following reasons - the speed is double: the strobe effects become negligible for screens from 80 to 230 m2.

- the 96 to 100 Hz flicker becomes invisible to the human eye - the light output is improved because the shutter speed is such that the illumination times can be increased by a factor of 1.5 consequently.

Contrast and colors, important factors in the subjective appreciation of the image are improved.

- the definition is improved by more than 30% compared to the 1 / 1.85 format at 24 frames / second. (1 / 1.85: 2 perforations 48 images / second = 84.6 cm2)
(1 / 2.00: 4 holes 24 images / second = 62.8 cm2)
The subjective quality of screen images up to 230 mZ is then satisfactory, the four factors on which it depends being improved.

 The new format has a recording ratio of around 2.00 (6). It is therefore located halfway between the requirements of HDTV recordings (ratio 1 / 1.77) (7), and the largest cinema screens (ratio 1 / 2.35) (8).

In addition to this practical aspect, (no more cruel dilemma between choosing an image recording intended for TV or cinema), it finally allows the room to choose a fixed screen ratio between 1 / 1.77 and 1 / 2.35 according to its architecture. (Ultimately, no more problems related to the use of mechanisms to vary the position of the screen covers in the rooms, and of mechanisms for changing the projector objectives).

For larger screens, the choice of 1 / 2.00 (9) format is recommended to obtain the best performance.
- When shooting, the operator must take into account the framing format (10), a ratio of about 1 / 2.00 so that the projection of the film is satisfactory for screen formats between 1/1 , 77 and 1 / 2.35.

The recording process on the main digital track (4) by
optical channel It allows recording: 5 main sound channels; 20 to 20,000 Hz
I bass channel; 20 to 200 Hz
6 channels dialogue + text; 20 to 10,000 Hz, (up to 6
different languages)
4 different signal channels
The method uses known techniques of synchronization, detection and error correction, as well as compression of analog signals among others:
- horizontal and vertical synchronization words
- CRC (error detection)
- Hamming code (Error correction) - Interpolation
- Interlacing
- MODEM
This list is not exhaustive.

Definition of tracks
Once the error correction has been carried out, the information is divided into words of 16
bits that are distributed chronologically according to the number of channels 20 KHz
of bandwidth desired to form the SON blocks. Likewise for channels
dialogue at 10 KHz bandwidth. we make word blocks of 16
bits to define them.

These blocks are then grouped into two SON blocks followed by a DIALOGUE block. Indeed,
10 KHz blocks are half as many as 20 KHz blocks.

To define the assignment of dialogues on the screen, 6 bits are added for the
set 3 bits defining the position of the left voice (8 combinations),
and 3 bits for the position of the right voice. These 6 bits are added to the block
DIALOGUE then comprising a combination of the different multilingual dialogues and their position.

Every 100 SOUND blocks, we put a BASS block comprising a 16-bit word, its bandwidth is then 200 Hz.

Also, there are TEXT tracks in which we can put subtitles or any other information intended to be displayed in front of the screen by another projection process such as the Laser or an electroluminescent display.

This information can also be used by advertisers. The text is an ASCII code with macro commands allowing to define attributes such as blinking, double size, etc. There are as many TEXT tracks as desired languages.

Finally, we include a SMPTE code track, a MIDI track, an INFO information track containing information about the film, and an undefined use track whose use is free.

The sampling frequency for the SON tracks is 44 KHz, or 16.44 Kbits per second, the compression rate being 4, a bit rate of 176 Kbits per second is required for each SON channel.

The TEXT, SMPTE, MIDI and INFO tracks have an identical total bandwidth of 176 Kbits per second, and form a track called TLV (Type Length Value); the
Type on 2 bits indicates If the TLV contains TEXT, an SMPTE code, a MIDI code or an INFO code; the length in words on 14 bits indicates the size of the value and the value is contained in the following words.

The final structure forming the WEFT of this process is therefore - 50 times
- 2 times
- a 16-bit SOUND block (5 words)
- a 16-bit TLV block (1 word)
- a 16-bit VOICE block (6 words) - a 16-bit BASS block (1 word)
Calculation of the total useful flow 6 t 176 Kbits / s + 6 t 6 + 6 * î76Kbits / s / 2 + 1 t 116 î76Kbits / s / 100
= 1586 Kbits / s
Taking into account the error detection and correction information which doubles the bit rate, the actual bit rate reaches around 3172 Kbits per second.

The surface available on 35 mm film is 455.04 mm (per second) t 2.527 mm (width of the digital track), or an area of 1150 mm square. This gives a compression utilization rate of approximately 361 microns square per bit, i.e. a square of 19 microns per side.

The possible bit rate of the digital optical track is 133 bits in the width of the film x 23,950 bits per second = 3185.35 Kbits / second.

AUXILIARY digital tracks (2) and (3) will be used to record and reproduce
digital information; for example, dialog channels
additional. The wear being more important at this point of the film, the
information will be significantly larger, and redundancy will be
such that we can always read the tracks reliably in operation.

 There are many industrial applications.

- Production costs will be close to current costs. We can consider that
the projectors in all the halls of the major operations will be gradually replaced by the new modified projectors (with no doubt a period of co-agreement).

- high definition or traditional telecine systems will be able to use this medium, and broadcast multilingual digital sound in several countries of different languages, as well as several multilingual texts.

- we can say that 'the whole cinematographic and audiovisual industries will be able to take advantage of this invention in multiple applications known and unknown to date.

Claims (4)

1) Cinematographic film characterized in that it comprises images (1) recorded on two perforations, main digital tracks (4) located to the left of the recorded images (1), analog tracks (5) located to the right of the recorded images (1), auxiliary digital tracks (2) and (3) located on the left and right edges of the rope. 2) Cinematographic film according to claim 1 characterized in that the images (1) are framed in the format of approximately 1 / 2.00 (10), and recorded in the format 1 / 2.00 (6), which allows a format operating between 1 / 1.77 (7) and 1 / 2.35 (8), passing by 1 / 2.00 (9). 3) Cinematographic film according to any one of the preceding claims, characterized in that the images (1) will be projected one by one at the rate of 48 to 50 images per second. 4) Cinematographic film according to any one of the preceding claims, characterized in that the images (1) can be projected one in two at the rate of 24 to 25 images per second.