in Todd-AO) and Patton (which had been filmed in a copycat process known as Dimension 150) were shown in some Cinerama cinemas, which allowed for deeply curved screens. Todd-AO adopted a similar multi-channel magnetic sound system to the one developed for Cinemascope two years earlier, recorded on "stripes" of magnetic oxide deposited on the film. However Todd-AO has six channels instead of the four of Cinemascope and due to the wider stripes and faster film speed provides superior audio quality. Five of these six channels are fed to five speakers spaced behind the screen, and the sixth is fed to surround speakers around the walls of the auditorium. Panavision and the 65/70 mm format Panavision developed their own 65/70 mm system that was technically compatible and virtually identical to Todd-AO. Monikered as Super Panavision 70, it used spherical lenses and the same 2.2:1 aspect ratio at 24 frames per second. Panavision also had another 65 mm system, (Ultra Panavision 70), which sprang from the MGM Camera 65 system they helped develop for MGM that was used to film Raintree County and Ben-Hur. Both Ultra Panavision 70 and MGM Camera 65 employed an anamorphic lens with a 1.25x squeeze on a 65 mm negative (as opposed to 35 mm CinemaScope which used a 2× compression, or 8-perf, horizontally filmed 35 mm Technirama which used a 1.5× compression). When projected on a 70 mm print, a 1.25× anamorphic projection lens was used to decompress the image to an aspect ratio of 2.76:1, one of the widest ever used in commercial cinema. Decline and resurgence Due to the high cost of 70 mm film and the expensive projection system and screen required to use the stock, distribution for films using the stock was limited, although this did not always hurt profits. Most 70 mm films were also released on 35 mm film for a wider distribution after the initial debut of the film. South Pacific (1958), Lawrence of Arabia (1962), My Fair Lady (1964), and The Sound of Music (1965) are well-known films widely shown in 70 mm format with a general release in 35 mm format. 70 mm film received a brief resurgence in the 1980s when it became popular to make "blow-up" prints of 35 mm titles. It had another resurgence in the mid-2010s with the release of The Master (2012), The Hateful Eight (2015) and Dunkirk (2017), with a small