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VCDIFF is a format and an algorithm for delta encoding, described in IETF's RFC 3284. The algorithm is based on Jon Bentley and Douglas McIlroy's paper "Data Compression Using Long Common Strings"[1] written in 1999.[citation needed] VCDIFF is used as one of the delta encoding algorithms in "Delta encoding in HTTP" (RFC 3229) and was employed in Google's Shared Dictionary Compression Over HTTP technology, formerly used in their Chrome browser.

Delta instructions

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VCDIFF has 3 delta instructions. ADD, COPY, and RUN. ADD adds a new sequence, COPY copies from an old sequence, and RUN adds repeated data.

Implementations

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Free software implementations include xdelta (version 3) and open-vcdiff.

See also

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References

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  1. ^ Bentley, Jon; McIlroy, Douglas (1999). Data compression using long common strings. DCC '99: Proceedings of the Conference on Data Compression. IEEE Computer Society. CiteSeerX 10.1.1.11.8470. doi:10.1109/DCC.1999.755678.
  2. ^ "Intent to Unship: SDCH". Retrieved 2017-08-08.
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  • RFC 3284 - The VCDIFF Generic Differencing and Compression Data Format


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Delta encoding

for directed delta encoding is VCDIFF, described in RFC 3284. Free software implementations include Xdelta and open-vcdiff. Generic Diff Format (GDIFF)

Xdelta

following the standardized VCDIFF format, and it realized the compatibility among other delta encoding software which supports the VCDIFF format.[citation needed]

SDCH

"sandwich", is a data compression algorithm created by Google, based on VCDIFF (RFC 3284). SDCH achieves its effectiveness by using pre-negotiated dictionaries

BCJ (algorithm)

allows it to be much better than the "match and copy" type tools such as VCDIFF, giving an output size of only 6% for Google Chrome. However, Google's courgette

Data compression

arXiv:2309.10668 [cs.LG]. Korn, D.; et al. (July 2002). "RFC 3284: The VCDIFF Generic Differencing and Compression Data Format". Internet Engineering

Delta update

Linux package manager pacman used to support a form of delta updating using VCDIFF (xdelta). It was scrapped due to an arbitrary command execution vulnerability

Data differencing

algorithm used in rsync. A standardized generic differencing format is VCDIFF, implemented in such utilities as Xdelta version 3. A high-efficiency (small

List of RFCs

Initiation Protocol June 2002 SIP RFC 3284 The VCDIFF Generic Differencing and Compression Data Format June 2002 VCDIFF RFC 3286 An Introduction to the Stream