Editing Print-through (section)

==Video recording==
Since analog video is recorded by [[frequency-modulation]] of the video signal, the FM [[capture effect]] shields the signal against this noise; however, the linear audio and (depending on format) [[chrominance]] signals of a video cassette may have some print effects.

While print-through is a form of unwanted noise, contact printing was used deliberately for high-speed recording (duplication, high speed ''en masse'' copying) of video tape, instead of having to record thousands of tapes on thousands of VCRs at normal playback speed, or recording the source material repeatedly in real time to large reels (without end caps) of tape (called pancakes) over 48 hours long to be inserted into cassettes.<ref>{{Cite web |last=Brown |first=Jim |date= |year= |orig-date=c.1987 |title=Consumer Video Tape Duplication Techniques: a Tutorial |url=http://audiosystemsgroup.com/AESConsumerVideotapeDup.pdf |series=AES 4th International Conference}}</ref> DuPont<ref>{{Cite magazine |date=11 September 1971 |title=New Duplicating Process |url=https://books.google.com/books?id=yggEAAAAMBAJ&q=dupont+thermal+duplication&pg=PA19 |magazine=Billboard |pages=19 |via=Google Books}}</ref> in conjunction with Otari<ref>{{Cite web|url=https://books.google.com/books?id=8CLAlJR6kuEC&q=dupont+thermal+duplication&pg=PA35|title=New Scientist|first=Reed Business|last=Information|date=April 14, 1988|publisher=Reed Business Information|via=Google Books}}</ref> invented a form of thermal magnetic duplication ("TMD") by which a high-coercivity metal mother master tape was brought into direct contact with a chromium dioxide copy (slave) tape. The coercivity of the mother tape is higher than that of the copy tape, so when the copy tape is heated and brought into contact with the mother tape, the copy tape gets a mirror image of the signal on the mother tape without the mother tape losing its signal. The recording on the mother tape was a mirror image of a valid video signal. Immediately before the copy tape came into contact with the mother tape, a focused laser beam heated it to its Curie point at which its value of coercivity dropped to very low values so that it picked up a near perfect copy of the mother tape as it cooled.<ref>{{Cite web|url=https://patents.google.com/patent/US3825948A/en|title=High speed thermal duplication of magnetic tape}}</ref><ref>{{Cite web|url=https://patents.google.com/patent/EP0240025B1/en|title=High speed thermomagnetic tape duplication}}</ref> The mother tape was made using a special reel to reel video tape recorder called a mirror master recorder<ref>{{Cite web|url=http://www.otari.com/support/vintage/r750/index.html|title=Otari, Inc.: Product Information: Service Information: Discontinued Products: R-750 Mirror Master Recorder|website=www.otari.com}}</ref> and was held inside the machine in an endless loop. This system could achieve speeds of up to 300 times playback speed in NTSC VHS SP mode, 900 times in VHS EP mode and 428 times in PAL/SECAM tapes.<ref>{{Cite web|url=http://www.otari.com/support/vintage/t710/index.html|title=Otari, Inc.: Product Information: Service Information: Discontinued Products: T-710 Video Duplicator|website=www.otari.com}}</ref>

Sony developed a system known as "Sprinter" that used a similar mother master tape forced into close contact with any blank copy tape using compressed air and run across a rotating transfer head in which a weak [[Alternating current|AC]] high frequency [[sine wave]] is used to transfer the information anhysteretically to the copy tape with minimal erasure of the mother tape on each pass. The sprinter does not use a laser to heat the copy tape which saves on power consumption. The transfer head may have a vacuum cleaner to reduce dropout caused by dust. This system was used to quickly duplicate VHS tapes at speeds of up to 240 times faster than playback speed for NTSC and 342 times for PAL/SECAM video signals without having to use expensive chrome dioxide tape; the tape was fed into the sprinter at a speed of 8 meters per second. The mother tape was enclosed in a space (not in a reel, but rather in an endless loop) in the Sprinter; this was made possible by a horizontal vibrating tape feed system where the edge of the endless loop tape sits in a table that diagonally vibrates using vibration generated by piezoelectric elements and amplified using mechanical oscillation, causing the tape in the table to move forward. The copy tape was unwound, recorded using the mother tape, then wound onto large reels (called pancakes) containing enough tape for several VHS cassettes. The mother tape had a coercivity three times that of normal VHS tape and was made by recording onto it using a special reel to reel video tape recorder called a mirror mother VTR using video from a [[D-2 (video)]], [[Type B videotape]] or [[Type C videotape]] master source tape. The video tape recorder had a sapphire blade to clean the surface of the mother tape, reducing dropout caused by dust. Sprinter mother tapes did suffer enough loss that they had to be replaced after a number of passes.<ref>{{Cite web| title=High Speed Video Duplicating System NTSC PAL SECAM Sprinter | url=http://www.digitrakcom.com/TechDocs/SONYsprinter.pdf | archive-url=https://web.archive.org/web/20200708033633/http://www.digitrakcom.com/TechDocs/SONYsprinter.pdf | archive-date=2020-07-08}}</ref> The master had to be replaced every 1000 copies.  This form of high-speed recording was very cost effective when recording in the EP (extra long play) mode because it was three times faster than recording in SP (standard play) mode while real-time recording took the same amount of time whether in EP mode that used less tape or SP mode that used a greater amount of tape. High-speed video recording of EP video produced far more consistent results than real-time recording at the slowest VHS speed. After duplication, the copy tape was loaded into video tape loaders that wound the tape into empty VHS cassette shells that contained only leader tape.<ref>{{Cite web|url=http://www.otari.com/support/vintage/vl322/index.html|title=Otari, Inc.: Product Information: Service Information: Discontinued Products: VL-322 Video Cassette Loader|website=www.otari.com}}</ref>