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{{Short description|Alleged data encoding technique}}

The '''Sloot Digital Coding System''' (SDCS) is an alleged technique for [[Data compression|data encoding]] claimed to have been invented in 1995 by '''Romke Jan Bernhard Sloot''' (1944–1999), an [[electronics engineer]] in the [[Netherlands]]. Sloot claimed his system could represent an entire [[feature film]] with only one [[kilobyte]] of data, a level of compression which is mathematically impossible according to [[Shannon's source coding theorem]].{{cn|date=September 2025}}

Sloot demonstrated the technology by recording and playing back video, apparently using a small [[smart card]] which stored a unique identifier by which any possible video could be referenced. He convinced entrepreneurs [[Roel Pieper]], [[Marcel Boekhoorn]], and [[Thomas Perkins (businessman)|Tom Perkins]] to invest in the technology. However, several days before the conclusion of a contract to sell his invention, Sloot died of a sudden [[heart attack]], and his [[source code]] was lost forever. His claims have never been reproduced or verified. Contrary to his claims, the playback device he used was discovered to contain a [[hard disk drive|hard drive]].

Software engineer Adam Gordon Bell speculated that Sloot had come upon a variation of [[shared dictionary compression]], a known technique. He speculates that Sloot believed in his idea because he failed to understand its mathematical limitations, and faked the demonstrations in order to buy time while refining the details.

== Background ==
Sloot was born in [[Groningen (city)|Groningen]] on 27 August 1944,  the youngest of three children. His father, a school headmaster, left his family quite soon after Sloot's birth.<ref name="Smit2006"/>{{rp|18}} Sloot was enrolled at a Dutch technical school, but dropped out early to work at a radio station.<ref name="ericsmit">{{cite book |first=Eric |last=Smit |title=Der SuperCode |year=2006 |trans-title=The SuperCode |language=Dutch |isbn=978-3431036329}}</ref>{{rp|20}} After fulfilling mandatory military service, Sloot settled in [[Utrecht]] with his wife.<ref name="Smit2006"/>{{rp|20}} He worked briefly for [[Philips Electronics]] in [[Eindhoven]]. He left this job in 1978 after a year and a half, starting his next job in [[Groningen]] at an audio and video store. A few years later he moved to [[Nieuwegein]] where he started his own company repairing televisions and stereos.

In 1984, Sloot began focusing on computer technology such as the [[Philips P2000]], [[Commodore 64]], [[IBM PC XT]], and [[IBM Personal Computer/AT|AT]]. Sloot developed the idea of a countrywide repair service network called ''RepaBase'' with a database containing details on all repairs carried out. This concept was the motivation to develop alternative data storage techniques that would require significantly less space than traditional methods.<ref name="Bell2023"/>

== Sloot Encoding System ==
In 1995, Sloot claimed to have developed a data encoding technique that could store an entire feature film in only 1 [[kilobyte]].  For comparison, a very low-quality video file normally requires several [[megabytes]], and a [[1080p]] movie requires about 3 gigabytes (3,221,225,472 bytes) per hour of playing time.<ref>{{cite web |author="Lance-AR" |title=Average 1080p Blu-Ray HB Encoded Movie Size? |url=https://forums.macrumors.com/threads/average-1080p-blu-ray-hb-encoded-movie-size.1474735/ |access-date=2022-04-23 |quote=iTunes lists my collection at 14.5 days of playtime and 1074.11 GB. That's a little over 3GB per hour...}}</ref>{{better source needed |date=April 2022}} {{As of|2022}}, just the plain text alone of the [[Dutch Wikipedia]] page describing the film ''[[Casablanca (film)|Casablanca]]'' occupies 29 kilobytes.

[[Roel Pieper]], former CTO and board member of [[Philips]], is quoted as saying (translated from Dutch):

{{blockquote|It is not about [[data compression|compression]]. Everyone is mistaken about that. The principle can be compared with a concept as [[PostScript|Adobe-postscript]], where sender and receiver know what kind of data recipes can be transferred, without the data itself actually being sent.<ref name="tcsoft"/><ref name="Spronck2004"/>}}

Pieter Spronck rebuts Pieper's [[codebook]] analogy by pointing out that Sloot claimed his invention was capable of encoding ''any'' video, not only those videos composed from a particular finite set of "recipes".<ref name="Spronck2004"/>

{{blockquote|In the [Sloot Digital Coding System], it is claimed that no movies are stored, only basic building blocks of movies, such as colours and sounds. So, when a number is presented to the SDCS, it uses the number to fetch colours and sounds, and constructs a movie out of them. Any movie. No two different movies can have the same number, otherwise they would be the same movie. Every possible movie gets its own unique number. Therefore, I should be able to generate any possible movie by loading some unique number in the SDCS.

Think of it: by placing the right number in the SDCS, I can not only get Orson Welles' ''[[Citizen Kane]]'' — I can get ''Citizen Kane'' in colour! Or ''Citizen Kane'' backwards! Or ''Citizen Kane'' where the credits misspell the name of [[Everett Sloane]][!...] Or ''Citizen Kane'' where Charles Foster Kane is replaced by [[Jar Jar Binks]]!

How many movies are possible that are variations on ''Citizen Kane''? More than fit in a number of one kilobyte, I can tell you.}}

In 1996, Sloot received an investment from colleague Jos van Rossum, a [[cigarette machine]] operator. The same year, Sloot and van Rossum were granted a 6-year Dutch patent for the Sloot Encoding System, naming Sloot as inventor and van Rossum as patent owner.<ref name="Sloot1998"/> The patent does not describe a compression scheme matching the claimed capabilities of the Sloot Encoding System.<ref name="Bell2023"/>

Despite the impossibility of the encoding system, Sloot received further investment. In early 1999, Dutch investor [[Marcel Boekhoorn]] joined the group. In March 1999, the system was demonstrated to Pieper. Pieper resigned from Philips in May 1999 and joined Sloot's company as CEO, which was re-branded as ''The Fifth Force, Inc.''<ref name="Klok2004"/> The story — including an account of a demonstration in which Sloot apparently recorded and replayed a randomly selected 20-minute [[cooking show|cooking program]] on a single [[smartcard]] — is told in modest detail in [[Thomas Perkins (businessman)|Tom Perkins]]' 2007 book ''Valley Boy: The Education of Tom Perkins''.<ref name="Perkins2007"/>

== Death of Sloot ==
On July 11, 1999, Sloot was found dead, in his garden<ref name="Bartels2001"/> at his home in Nieuwegein, of an apparent [[myocardial infarction|heart attack]].<ref name="Klok2004"/> He died one day before the deal was to be signed with Pieper. The family consented to an autopsy, but none was performed.{{citation needed|date=February 2019}}

Perkins, the co-founder of the Silicon Valley venture capital firm [[Kleiner Perkins]], had agreed to invest in the technology when Sloot died.<ref name="Perkins2007"/> Perkins and Pieper would have proceeded after Sloot's death, but a key piece of the technology, a compiler stored on a [[floppy disk]],<ref name="Perkins2007"/> had disappeared and, despite months of searching, was never recovered.<ref>{{Cite web|url=https://usbeketrica.com/article/jan-sloot-ingenieur-mort-informatique|title=Jan Sloot, l'ingénieur mort juste avant d'avoir changé le monde|website=usbeketrica.com|access-date=2019-09-09|language=French|trans-title=Jan Sloot, the engineer who died just before changing the world}}</ref>

After his death, a software engineer Sloot had worked with analysed Sloot's demonstrations. Despite Sloot's claim that his coding system stored all of its data on smart cards, his demonstration device was found to contain a hard disk. Bell says that Sloot seems to have believed that he had created a novel [[encryption]] technology, but posthumous analysis suggests that he had actually created a variation of [[shared dictionary compression]], a known data compression technique with predictable and finite mathematical limitations. Bell speculates that Sloot thought he could overcome these limitations with better coding, and faked the demonstrations to buy time to improve the code, but that the inherent mathematical limitations of the coding system would have inevitably proven impossible to overcome.<ref name="Bell2023"/>
{{blockquote|I think Sloot thought his system could work, that he could find a way to store all possible movies in his RepaBase encoding system and look each up with a key, but he just hadn't cracked it yet. And yet, in the meantime, to get people interested, while he worked out the details, Yeah, he faked some demos. He said it's not compression, this is a key to unlock the movie. But{{nbsp}}... there are more possible movies than can be represented with a one kilobyte key. A one kilobyte key is like less than one bit per frame of a two hour movie. It's like trying to give a unique name to a billion people using just a thousand names. No matter how you rearrange it, you can't avoid some people getting the same name.}}

== See also ==
* [[Lost inventions]]

== References ==
<references>
<ref name="Bartels2001">{{Cite AV media notes |title=De Broncode Deel |year=2001 |author=Vladimir Bartels |type=video documentary |lang=nl}}</ref>

<ref name="Klok2004">{{cite web |author=Peter Klok |date=2004-09-20 |title=Tv-reparateur nam geheim mee in zijn graf |trans-title=TV repairman took secret to his grave |url=http://www.volkskrant.nl/wetenschap/tv-reparateur-nam-geheim-mee-in-zijn-graf~a715369/ |language=nl}}</ref>

<ref name="Perkins2007">{{cite book |title=Valley boy: the education of Tom Perkins |last=Perkins |first=Thomas |author-link=Thomas Perkins (businessman) |publisher=Gotham Books |location=New York |year=2007 |url=https://archive.org/details/valleyboyeducati00perk |url-access=registration |isbn=9781592403134 |oclc=122423908 |pages=209–217}}</ref>

<ref name="Sloot1998">
{{cite patent |country=NL |number=1009908C2 |status=patent |title=Storage system for digital data relating to text or bit-map elements, involves storing possible values in coding memories and chopping incoming data into blocks for comparison with stored codes |pubdate= |gdate=2000-05-01 |fdate=1998-08-20 |pridate=1998-08-20 |inventor=Romke Jan Bernhard Sloot}}</ref>

<ref name="Smit2006">{{cite book |author=Eric Smit |title=Der SuperCode |year=2006 |trans-title=The SuperCode |language=nl |isbn=978-3431036329}}</ref>

<ref name="tcsoft">{{cite web |author="CaptainCosmos" |title=The Sloot Digital Coding System is not about compression |date=2006-09-17 |url=http://jansloot.telcomsoft.nl/Sources-1/More/CaptainCosmos/Not_Compression.htm |language=English}}</ref>

<ref name="Spronck2004">{{cite web |author=Pieter Spronck |title=The Stick of Jan Sloot |url=http://www.spronck.net/sloot.html |date=2004-09-28 |access-date=2022-04-23}}</ref>

<ref name="Bell2023">{{cite web |author=Adam Gordon Bell |title=Sloot Digital Coding System: Lost Compression System or Cautionary Tale? |url=https://corecursive.com/sloot-digital-coding-system/ |date=2023-10-02 |access-date=2024-09-07}}</ref>

</references>

== External links ==
* [https://web.archive.org/web/20120204082016/https://doc.telin.nl/dsweb/Get/Document-21154/Babet_Final_Report.pdf Broadband applications on limited bandwidth networks] ([[Portable Document Format|PDF]]) – see section 3.1.5, "Beyond the limits?"
* "[http://jansloot.telcomsoft.nl/ Jan Sloot - The Source Code]", Dutch-language website devoted to Jan Sloot and Sloot Coding System
* [https://www.youtube.com/watch?v=4V-qrQd87xY "The Source Code Part 1"] [https://www.youtube.com/watch?v=_859WLprRIE "The Source Code Part 2"] Dutch-Language News Segment Regarding Jan Sloot

===Related patents===
* [http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=NL1005930C&F=0&QPN=NL1005930C NL1005930C]: Sloot, Romke Jan Bernhard/J.V.R Services Nieuwegein BV: ''Compression of video data'' (02–11–1998)
* [http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=NL1009908&F=0 NL1009908]: Sloot, Romke Jan Bernhard: ''Storage system for digital data relating to text or bit-map elements, involves storing possible values in coding memories and chopping incoming data into blocks for comparison with stored codes'' (22–02–2000)

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[[Category:Video compression]]
[[Category:Lost inventions]]
[[Category:Dutch inventions]]