View source for Video Floppy

{{ infobox media
| logo          = 
| image         = Video Floppy Disk - front (gabbe).jpg
| caption       = A Video Floppy disk
| type          = 
| encoding      = [[NTSC]], [[PAL]], [[SECAM]]
| capacity      = 
| read          = 
| write         = 
| standard      = [[EIAJ]] CP-3901<br/>BS EN 61122:1994
| owner         = [[Sony]]
| use           = 
| extended from = 
| extended to   = 
}}

'''Video Floppy''' ({{nihongo||ビデオフロッピー|bideo furoppi-|lead=yes}}), also known as '''VF disc''' and introduced under the "'''Mavipak'''" name, is an [[analog recording]] storage format for [[still video camera]]s. It consists of a 2-inch magnetic [[floppy disk]] used to store still frames of [[composite video|composite]] [[analog video]].

A video floppy could store up to 25 frames either in the [[NTSC]] or [[PAL]] video standards, with each frame containing 2 [[field (video)|field]]s of [[interlaced video]].  The video floppy also could store 50 frames of video, with each frame of video only containing one field of video information, recorded or played back in a "[[skip-field]]" fashion.

== History ==
[[file:SONY 2 inch floppy disk.jpg|alt=|thumb|Prototype MAVIPAK, Production version Mavipak, 2inch Data Disk for PRODUCE]]

Video floppies were first demonstrated by [[Sony]] and introduced under the ''Mavipak'' name in 1981 for their prototype [[Mavica]] (not to be confused with their later line of Mavica digital cameras introduced in the mid-1990s, which stored [[JPEG]] images to standard 3.5-inch floppy disks readable by computers instead).<ref name=MoOM-VF>{{cite web |url=https://obsoletemedia.org/2-inch-floppy-disk-video-floppy/ |title=2-inch floppy disk (Video Floppy) (1986 – 1990s) |date=2 May 2013 |publisher=Museum of Obsolete Media |access-date=15 November 2021}}</ref> The video floppy specification was proposed by the Electronic Still Camera Conference in 1985<ref>{{cite conference |title=Specification of Still Video Floppy Systems |date=1985 |publisher=The Electronic Still Camera Conference}}</ref> and established as Standard CP-3901 (formerly CPZ-250) of the [[Electronic Industries Association of Japan]] (EIAJ) in September 1988.<ref name=Iwabe-93>{{cite journal |doi=10.3169/itej1978.47.863 |title=電子スチルカメラに関する規格 |lang=ja |trans-title=Standards for electronic still cameras |author1=岩部 和記 |date=1993 |volume=47 |number=6 |journal=プ/テレビジョン学会誌 [J-STAGE] |pages=863–865|doi-access=free }}</ref> The video floppy format was later used by [[Minolta]], [[Panasonic]], and [[Canon (company)|Canon]] for their still video cameras introduced in the mid-to-late 1980s, such as the Canon [[Xapshot]] from 1988 (also known as the Canon Ion in Europe and the Canon Q-PIC in Japan).

[[File:Video Floppy Disk - back (gabbe).jpg|thumb|right|Reverse side of still video floppy]]
Besides still video cameras, stand-alone recorders & players were also available for the VF format, that could record from or output a composite video signal, to or from an external source (such as a [[video camera]], [[VCR]], [[video capture card]], or computer graphics output).  Some VF recorders also had the feature of recording a couple of seconds of audio that accompanied each video frame.

== Design ==

The recording media in a video floppy is a flexible magnetic disk {{cvt|47|mm}} in diameter and {{cvt|40|μm}} thick.<ref name=US4609949A/> The disk is housed in a rectangular cartridge with one chamfered corner for orientation, measuring {{cvt|60|×|54|×|3.6|mm}}; the cartridge is equipped with a sliding shutter for dust protection and a hub opening that is {{cvt|15.9|mm}} in diameter.<ref name=US4609949A/> The magnetic disc is divided into 52 coaxial tracks and rotates at either 3600&nbsp;RPM to match the NTSC video field frequency (60 fields/second) or 3000&nbsp;RPM for PAL and SECAM (50 fields/second) instead.<ref name=Iwabe-93/> The first track is encoded with a radius of {{cvt|20|mm}}; each track is {{cvt|60|μm}} wide with a track-to-track pitch of {{cvt|100|μm}}; the second track is recorded inboard of the first at a radius of {{cvt|19.9|mm}}, and so on until the 52nd track is encoded with a radius of {{cvt|14.7|mm}}.<ref>{{cite book |chapter-url=https://books.google.com/books?id=UY6QzgzgieYC&pg=PA7 |title=Image Sensors and Signal Processing for Digital Still Cameras |editor=Nakamura, Junichi |chapter=1: Digital Still Cameras at a Glance |author=Toyoda, Kenji |date=2005 |publisher=CRC Press/Taylor & Francis |location=Boca Raton, Florida |isbn=978-1-4200-2685-6 |pages=6–7}}</ref> Track 51 is reserved as blank (without information), and Track 52 is used for a control signal.<ref name=Iwabe-93/>

The analog signal recorded to each track corresponds to a single field and includes three frequency-modulated waveforms: the luminance information, and red (R-Y) and blue (B-Y) color difference chrominance signals.<ref name=US4609949A/> Luminance is recorded between 6&nbsp;MHz and 7.5&nbsp;MHz (white peak); the R-Y signal has a center band of 1.2&nbsp;MHz with a 0.7&nbsp;MHz bandwidth and the B-Y signal has a center band of 1.3&nbsp;MHz with a 0.5&nbsp;MHz bandwidth. The Hi-Band format developed in 1988 shifts the luminance signal to between 7.7 and 9.7&nbsp;MHz, improving the signal-to-noise ratio and resolution.<ref name=Iwabe-93/>

The patent for the data variant of the Video Floppy was filed by [[Ken Kutaragi]] and assigned to [[Sony Corporation]].<ref name=US4609949A>{{cite patent |number=4609949 |country=US |title=Magnetic disc reproducing apparatus |inventor1-first=Ken|inventor1-last=Kutaragi|inventor1-link=Ken Kutaragi |pridate= 1984-05-21 |fdate=1985-05-13 |pubdate= 1986-09-20 |status=patent |assign=[[Sony Corp]]}}</ref> This patent describes a formatting scheme that allows the disk to record digital data. In this scheme, each track is divided into 4 angular sectors known as blocks, with each block spanning an angle of 90°. Within each block, there is a 4° gap to afford margin against overwriting the succeeding (or preceding) block, followed by a 1° interval reserved for a burst signal that states the recording density and indicates the disk is encoded with digital data. After the burst signal, a 64-bit index signal is used to record the data address (track and block information) along with a checksum signal. The remainder of the block is formatted into 128 distinct frames, each capable of recording 32 bytes, making the formatted capacity of the Video Floppy 800 Kbytes (50 tracks × 4 blocks/track × 128 frames/block × 32 bytes/frame).<ref name=US4609949A/>

== Other applications ==

The video floppy was used in multiple applications during the 1980s and 1990s.  Many medical [[endoscopy]] and [[dentistry]] video systems, as well as industrial video [[borescope]]s & [[fiberscope]]s, used VF disks for storing video images for later playback and study.  Standalone VF recorders & players were also used by [[television station]]s and [[video production studio]]s as a [[still-store]] system for stills & graphics for use in a television production, or for on-air slides used for station identification or during technical difficulties (such as a "Please Stand By" still).<ref name=MoOM-VF/>

The video floppy was available as a data variant, which was sold as the Sony 2inch Data Disk PD-1 for use in its own PJ-100 "PRODUCE 100" word processor.The PRODUCE series began with the 100 and later included several other models, such as the 200, 300, 1000, 575, and 2000.<ref>{{cite web |url=http://crimson-systems.com/media/fd2/index.htm |title=２型フロッピー,スチルビデオフロッピー |trans-title=Type 2 floppy, still video floppy |lang=ja |publisher=Crimson Systems |access-date=15 November 2021}}</ref><ref>{{cite web |url=http://museum.ipsj.or.jp/en/computer/word/0045.html |title=Sony PJ-100 |publisher=IPSJ Computer Museum |access-date=15 November 2021}}</ref> A similarly sized disk was also used by the [[Zenith MinisPort]] laptop computer from 1989, digitally formatted for data storage. The MinisPort could store up to 793&nbsp;KB of information on 2-inch LT format disks called [[Fujifilm LT-1|LT-1]].<ref>{{cite web |url=http://www.computinghistory.org.uk/det/57098/Fuji-Film-LT-1-2-inch-Floppy-Disk/|title=Fuji Film LT-1 2-inch Floppy Disk |publisher=center for computing history |access-date=15 November 2021}}</ref> Video floppy and LT-1 are neither physically nor digitally compatible, so media can not be interchanged between drives using video floppy or LT standards.<ref>{{cite web |url=https://obsoletemedia.org/lt-1/|title=2-inch floppy disk (LT-1) (1989 – early 1990s) |date=22 July 2017 |publisher=Museum of Obsolete Media |access-date=15 November 2021}}</ref>

An enhanced version of the VF format called ''Hi-VF'' was introduced in the late 1980s, providing higher resolution per video still than its predecessor.  It used higher-bandwidth video recording, much like [[S-VHS]] as compared to [[VHS]], or [[Hi8]] compared to [[Video 8]].

== See also ==

* [[Still video camera]]
* [[Floppy disk]]

== References ==

{{refs}}

== External links ==

* {{cite journal |title=The Electronic Still Camera, a New Concept in Photography |author1=Kihara, N. |date=August 1982 |volume=CE-28 |issue=3 |journal=IEEE Transactions on Consumer Electronics |pages=325–335|doi=10.1109/TCE.1982.353928 |s2cid=45483442 }}
* {{cite journal |doi=10.1109/TCE.1986.290053 |title=An Electronic Still Camera System |author1=Tanaka, Tatsuo |author2=Maedo, Satoru |author3=Yonei, Hiroshi |author4=Hirai, Tadashi |author5=Kuroda, Sakuro |date=August 1986 |volume=CE-32 |issue=3 |journal=IEEE Transactions on Consumer Electronics |pages=345–354|s2cid=3005831 }}
* {{cite web |url=http://www.peterjsucy.com/History/1987/SVFSpecSheet.pdf |title=the still video floppy |website=Peter J Sucy}}
* [http://www.digicamhistory.com Digicamhistory.com, which features several VF & HiVF cameras from the late 1980s & early 1990s]
* [http://www.garpenholm.se/vf-50/ Garpenholm: The Video Floppy Disk home page]

[[Category:Video storage]]
[[Category:Composite video formats]]
[[Category:Floppy disk drives]]
[[Category:Japanese inventions]]