Editing 35 mm movie film (section)

===Innovations in sound===
[[File:35mm film audio macro.jpg|thumb|upright=0.9|A photo of a 35&nbsp;mm film print featuring all four audio formats (or "quad track") — from left to right: [[Sony Dynamic Digital Sound|SDDS]], a soundtrack as an image of a digital signal (blue area to the left of the sprocket holes); [[Dolby Digital]] sound (grey area between the sprocket holes labelled with the Dolby "Double-D" logo in the middle); [[Dolby Stereo|analog optical sound]], optically recorded as waveforms containing the audio signals for the left and right audio channels (the two white lines to the right of the sprocket holes); and the [[Digital Theater System|DTS]] [[time code]] (the dashed line to the far right).]]
When film editing was done by physically cutting the film, editing the picture could only have been done on the frame line. However, the sound was stored for the whole frame between each of the four sprocket holes, and so the sound editors could cut on any arbitrary set of holes, and thus get {{frac||1|4}}-frame edit resolution. With this technique, an audio edit could be accurate to within 10.41&nbsp;[[Millisecond|ms]]."<ref name=Rose>{{cite book |hdl=1853/50482 |chapter=Reality (sound)bites: Audio tricks from the film and TV studio |title=International Conference on Auditory Display |last=Rose |first=Jay |date=July 2003}}</ref><sup>1–2</sup> A limitation of [[Analog recording|analog optical recording]] was the audio frequency would cut off, in a well-maintained theater, at around 12[[Hertz|kHz]].<ref name=Rose/><sup>4</sup> Studios would often record audio on the transparent film strips, but with [[magnetic tape]] on one edge; recording audio on full 35&nbsp;mm magnetic tape was more expensive.<ref name=Rose/><sup>5</sup>

Three different digital soundtrack systems for 35&nbsp;mm cinema release prints were introduced during the 1990s. They are: [[Dolby Digital]], which is stored between the perforations on the sound side; [[Sony Dynamic Digital Sound|SDDS]], stored in two [[redundancy (engineering)|redundant]] strips along the outside edges (beyond the perforations); and [[Digital Theatre System|DTS]], in which sound data is stored on separate [[compact disc]]s synchronized by a [[timecode]] track on the film just to the right of the analog soundtrack and left of the frame.<ref>{{cite web |url=http://www.dts.com/Corporate/About_Us/Milestones.aspx |website=DTS |title=Corporate Milestones |url-status=dead |archive-url=https://web.archive.org/web/20100609183206/http://www.dts.com/Corporate/About_Us/Milestones.aspx |archive-date=2010-06-09 }}</ref> Because these soundtrack systems appear on different parts of the film, one movie can contain all of them, allowing broad distribution without regard for the sound system installed at individual theatres.

The analogue optical track technology has also changed: in the early years of the 21st century, distributors changed to using [[cyan]] dye optical soundtracks instead of applicated tracks, which use environmentally unfriendly chemicals to retain a silver (black-and-white) soundtrack. Because traditional [[Incandescent light bulb|incandescent]] [[Optical sound#Film and radio|exciter lamps]] produce copious amounts of [[infrared light]], and cyan tracks do not absorb infrared light, this change has required theaters to replace the incandescent exciter lamp with a complementary colored red [[LED]] or [[Laser light|laser]]. These LED or laser exciters are backwards-compatible with older tracks.<ref name="cyan">{{cite web |last=Hull |first=Joe |url=http://www.dyetracks.org/FJI_Sept04.pdf |title=Committed to Cyan |website=dyetracks.org |access-date=August 11, 2006 |url-status=dead |archive-url=https://web.archive.org/web/20060921125129/http://www.dyetracks.org/FJI_Sept04.pdf |archive-date=September 21, 2006 }}</ref> The film ''[[Anything Else]]'' (2003) was the first to be released with only cyan tracks.<ref name="cyan" />

To facilitate this changeover, intermediate prints known as "high magenta" prints were distributed. These prints used a silver plus dye soundtrack that were printed into the magenta dye layer. The advantage gained was an optical soundtrack, with low levels of sibilant (cross-modulation) distortion, on both types of sound heads.<ref name="kodak-cyan">{{cite web |website=Kodak |url=http://motion.kodak.com/US/en/motion/Support/Technical_Information/Lab_Tools_And_Techniques/Cyan_Dye_Tracks/guide.htm |title=Cyan Dye Tracks Laboratory Guide |url-status=dead |archive-url=https://web.archive.org/web/20091126055003/http://motion.kodak.com/US/en/motion/Support/Technical_Information/Lab_Tools_And_Techniques/Cyan_Dye_Tracks/guide.htm |archive-date=2009-11-26 }}</ref>