Introduction of sound
- Related Topics:
- film
- technology
The popularity of the motion picture inspired many inventors to seek a method of reproducing accompanying sound. Two processes were involved: recording and reproducing. Further, the sound reproduction had to be presented in an auditorium and had to be quite good. This could not be achieved without a good amplifier of electrical signals. In 1907 Lee De Forest invented the Audion, a three-element vacuum tube, which provided the basis in the early 1920s for a feasible amplifier that produced an undistorted sound of sufficient loudness.
Next came the problem of synchronization of the sound with the picture. A major difficulty turned out to be the securing of constant speed in both the recorder and reproducer. Many ingenious ideas were tried. In 1918 in Germany, the use of a modulated glow lamp in photographically recording sound and a photocell for reproduction were studied. In Denmark in 1923, an oscillograph light modulator and selenium-cell reproducer were developed. De Forest tried a gas-filled glow discharge operated by a telephone transmitter to record a synchronized sound track on the film. For loudspeakers he experimented with a variety of devices but finally chose the speaker with horn. The operating signal was obtained from a light shining through the film sound track and detected by a light-sensitive device (photocell). These were used in a system called Phonofilm, which was tried experimentally in a number of theaters. In 1927 the Fox Film Corporation utilized some of these principles in the showing of Fox Movietone News.
Meanwhile, the Western Electric Company laboratories in the United States had been making extensive studies on the nature of speech and other sounds and on techniques for recording and reproducing such sounds. They experimented with recording on a phonograph disc and developed a 16-inch (40.6-centimeter) disc rotated at 33 1/3 revolutions per minute; they improved loudspeakers, introduced the moving-coil type of speaker, and generally improved the entire electronic amplification system. The Warner Bros. movie studio became interested in all these developments and formed the Vitaphone Corporation to market the complete system.
Warner Bros. premiered Vitaphone in 1926 with a program featuring short musical performances and a full-length picture, Don Juan, which had synchronized music and effects but no speech. In 1927 it brought out The Jazz Singer, which was essentially a silent picture with Vitaphone score and sporadic episodes of synchronized singing and speech. Warners presented the first “100-percent talkie,” The Lights of New York, in 1928.
Although the Vitaphone system offered fidelity superior to sound-on-film systems at this stage, it became clear that recording on film would be much more convenient. Among other disadvantages, it was extremely difficult with the wax discs to shoot outdoors or to edit sound. By 1931 Warner Bros. ceased production of sound-on-disc and adopted the sound-on-film option preferred by the other studios.
Sound-on-film, a system that in various guises had enjoyed several periods of popularity, underwent constant improvements in the 1910s and 1920s. Although a sound track on the picture negative was used for Movietone News, Fox’s dramatic productions used a separate sound film on fine-grain print stock that could be edited apart from the picture yet in synchronism with it. One serious problem of sound-on-film systems had been the distortion of the signal introduced by the glow lamp when recording the sound track on film. The Western Electric Company devised a “double-string” light valve. A wire was looped around a post and parallel to itself. When speech current was applied to the wire in a magnetic field, the wire vibrated toward and away from itself according to the applied electrical waveform. A steady beam of white light shining through the loop was modulated in intensity by the varying gap between the wires; the modulated beam was photographed while masked by a slit perpendicular to the edge of the film. The resulting sound track appeared as darker or fainter parallel lines on the edge of the film. Known as the variable density system, this method of optically recording sound was originally used by all but one of the major Hollywood studios.
The Radio-Keith-Orpheum Corporation (RKO) was created in 1928 to showcase the Radio Corporation of America (RCA) Photophone system of variable area recording. With this system, the sound recording was modulated by a rotating mirror and the slit was parallel to the edge of the film; reproduction employed the perpendicular slit of the variable density sound track. Minor problems of incompatibility between recording and reproduction were solved in late 1928 when the track was narrowed down to stay safely within the area scanned by the beam. Identical side-by-side tracks were employed to compensate for lateral misalignment. Initially inferior in quality, the variable area system gradually drew even with the quality of the density system and supplanted it altogether in the 1950s.
Whereas there was wide variation in the speed at which silent films were photographed and projected, sound necessitated standardization of the frame rate. In 1927 the speed was standardized at 24 frames per second, or 90 feet per minute for 35-mm film.
The development of sound technology in the first years of talking pictures focused on two areas. One involved the development of blimped cameras, directional microphones, microphone booms, and quieter lights, so that sound could be recorded more cleanly at the time of shooting. The other technologies involved the ability to add, edit, and mix sound separately from the time the picture was recorded.
Pierre Mertz Elisabeth Weis Stephen G. HandzoIntroduction of color
From their earliest days, silent films could be colored using nonphotographic methods. One means was to hand-color frames individually. Another method made it possible to use monochrome sections for mood (e.g., blue for night scenes or red for passionate sequences). Monochrome stock was created by “tinting” the film base or “toning” the emulsion (by bathing the film in chemical salts).
The photography of color was theorized decades before it was developed for motion pictures. In 1855 the British physicist James Clerk Maxwell argued that a full-color photographic record of a scene could be made by filming three separate black-and-white negatives through filters colored, respectively, red, green, and blue, the three primary colors. When converted to positives, the transparent exposed areas of the three films could pass light through the appropriate filter to produce three images, one red, one green, and one blue. Superimposing the three images would “rebuild” the image in its original colors.
In 1868 Louis Ducos du Hauron identified the additive and subtractive systems of color. Both systems originate as red, green, and blue negative records. The difference occurs in the positive image, which may be composited from either the additive or subtractive primaries. The subtractive primaries—cyan, magenta, and yellow—are the complements of the additive primaries and can be obtained by subtracting, respectively, red, green, and blue from white. (Subtracting all three additive primaries yields black; adding all three yields white.)
In motion-picture prints, overlapping dye layers in the three subtractive primaries are simultaneously present on a clear, transparent base, and the image is projected with an exposure of white light. The dark areas of the cyan layer subtract all red color, permitting only cyan (the mixture of blue and green) to pass through; the transparent areas pass all the white light. The magenta and yellow layers act similarly, and the original color image is reproduced. The fineness of resolution is limited only by the structure of photographic grain or dye globules.
The first film color systems were additive, but they were confronted by insurmountable limitations. In an additive system, the three color records remain discrete and meet only as light rays on the screen. The best picture results when a separate film is made for each color; however, each color can occupy alternating frames or small, alternating portions of each frame of a single film. (A contemporary example of additive color can be seen in projection television, in which red, green, and blue lenses converge to produce an image so enlarged that the separate color areas, or dots, become discernible.)
The best known of the early additive processes was Kinemacolor (1906), which, for manageability, reduced the three color records to two: red-orange and blue-green. A single black-and-white film was photographed and projected at 32 frames per second (twice the normal silent speed) through a rotating color filter. The two color records occupied alternate frames and were integrated by the retention characteristic of the human eye. As there were no separate red-orange and blue-green records for each image, displacement from frame to frame was visible during rapid movement, so that a horse might appear to have two tails. Inventors tried to increase the film speed, reduce the frame size, or combine two films with mirrored prisms, but additive systems continued to be plagued by excessive film consumption, poor resolution, loss of light, and registration problems.
The first subtractive process employing a single film strip in an ordinary projector without filters was Prizma Color in 1919. (Prizma Color had been introduced as an additive process but was soon revised.) The basis was an ingenious “duplitized” film with emulsion on both sides. One side was toned red-orange and the other blue-green. The stock long outlasted the Prizma company and was in use as late as the early 1950s in such low-cost systems as Cinecolor.
Similar enough to provoke litigation was an early (1922) process by Technicolor in which separate red and green films were cemented back-to-back, resulting in a thick and stiff print that scratched easily. Although only four two-color Technicolor features were produced by the end of the silent era, Technicolor sequences were a highlight of several big-budget pictures in the mid-to-late 1920s, including The Phantom of the Opera (1923–25) and Ben Hur (1925). Technicolor devised the first of its dye-transfer, or imbibition, processes in 1928. Red and green dye images were printed onto the same side of clear film containing a black silver sound track.
When Technicolor’s appeal seemed on the wane, it devised a greatly improved three-register process (1932). The perfected Technicolor system used a prism/mirror beam-splitter behind a single lens to record the red, green, and blue components of each image on three strips of black-and-white film. Approximately one-third of the light was transmitted to the film behind a green filter in direct path of the lens; the film was sensitized to green light by special dyes. A partially silvered mirror (initially flecked with gold) directed the remainder of the light through a magenta (red plus blue) filter to a bi-pack of orthochromatic and panchromatic films with their emulsion surfaces in contact. The orthochromatic film became the blue record. As it was insensitive to red light, the orthochromatic film passed the red rays to the panchromatic film. A 1938 improvement added red-orange dye to the orthochromatic film so that only red light reached the panchromatic layer. In 1941 Monopack Technicolor was introduced. This was a three-layer film from which separation negatives were made for the Technicolor dye-transfer printing process.
Using the dye-transfer method, it was necessary to make gelatin positives that contained the image in relief. Dye filled the recesses while the higher areas remained dry. Each gelatin matrix thus imprinted its complement onto the film base. As in the two-color process, a black silver sound track was printed first on clear film. When magnetic sound became popular, the oxide strips were embossed after printing. Technicolor gave excellent results but was very expensive.
In 1936 Germany produced Agfacolor, a single-strip, three-layer negative film and accompanying print stock. After World War II Agfacolor appeared as Sovcolor in the Eastern bloc and as Anscocolor in the United States, where it was initially used for amateur filmmaking. The first serious rival to Technicolor was the single-strip Eastmancolor negative, which was introduced in 1952 by the Eastman Kodak Company but was often credited under a studio trademark (e.g., Warnercolor). Eastmancolor did not require special camera or processing equipment and was cheaper than Technicolor. Producers naturally preferred the less expensive Eastmancolor, especially since they had, in response to the perceived threat of television, increased production of color films. (After the 1960s black-and-white films were so rare that they cost more to print than color films.) The 1950s vogue for CinemaScope and three-dimensional productions, both incompatible with the Technicolor camera, also hastened the demise of Technicolor photography.
Dye-transfer printing remained cost-effective somewhat longer, but Technicolor was forced to abandon the process in the 1970s. This has created a significant problem for film preservationists because only Technicolor film permanently retains its original colors. Other color prints fade to magenta within seven years, yet the hard gelatin dyes of a Technicolor print remain undimmed even after the film’s nitrate base has begun to decompose.
In the 1980s computerized versions of the hand-stenciled color films of the silent era were developed to rejuvenate old black-and-white films for video.
Elisabeth Weis Stephen G. Handzo