Jean-Claude Risset/Lillian Schwartz Mutations (1969)

French composer Jean-Claude Risset helped to pioneer computer music at Bell Labs in the early 1960s. Made in collaboration with computer pioneer Lillian Schwartz, this film sets animations by Ken Knowlton and others to Risset’s titular composition for solo tape, which features a seemingly infinite glissando among its effects.

Lillian F. Schwartz (born 1927) is an American artist who is known for being a creator of 20th century computer-developed art. One notable work she created is Mona Leo, where she morphed the image of a Leonardo da Vinci self-portrait with the Mona Lisa.
She made one of the first digitally created films to be shown as a work of art, Pixillation, which shows diagonal red squares and other shapes such as cones and pyramids on black on white backgrounds.
She worked in the early stages of her career with Bell Laboratories, developing mixtures of sound, video, and art. Afterwards, during the 1980s, Schwartz experimented with manipulating artwork images using computer technology and creating artwork of her own.

Jean-Claude Risset (18 March 1938 in Le Puy, France) is a French composer, best known for his pioneering contributions to computer music. He is a former student of André Jolivet and former coworker of Max Mathews at Bell Labs.
Arriving at Bell Labs, New Jersey in 1964, he used Mathew’s MUSIC IV software to digitally recreate the sounds of brass instruments. He made digital recordings of trumpets and then studied their timbral composition using „pitch-synchronous“ spectrum analysis tools, revealing that the harmonics of these instruments would differ greatly depending on pitch, duration and loudness. He is also credited with performing the first experiments on a range of synthesis techniques including FM Synthesis and waveshaping.
After the discrete Shepard scale Risset created a version of the scale where the steps between each tone are continuous, and it is appropriately called the continuous Risset scale or Shepard-Risset glissando.
A Shepard-Risset glissando
He has also created a similar effect with rhythm in which tempo seems to increase or decrease endlessly.