VCDIFF

VCDIFF is a data format and algorithm for delta encoding and is described in RFC 3284 . The algorithm is based on the work Data Compression Using Long Common Strings from 1999 by Jon Bentley and Douglas McIlroy. VCDIFF is one of the delta encoding formats in delta encoding in HTTP ( RFC 3229 ) and is used in Google's Shared-Dictionary-Compression-Over-HTTP technology in the Chrome browser .

Delta statements

VCDIFF uses three delta statements: ADD, COPY, and RUN. ADD adds a new sequence, COPY uses a previous sequence and RUN adds repeating data areas.

Implementations

Implementations as free software are Xdelta (version 3) and open-vcdiff.

• Google's proposal for Shared Dictionary Compression Over HTTP has been implemented in the Chrome browser.
• Xdelta : An open source tool that implements the VCDIFF delta compression algorithm.
• open-vcdiff: Another open source implementation of the delta compression algorithm.
• vczip: Part of the vcodex and ast-open packages (also included in UWIN ).
• diffable: Java implementation with additional extensions.
• jvcdiff: Complete encoder / decoder implementation in Java.
• j-vcdiff: Another Java implementation of VCDIFF.
• Miscellaneous Utility Library: C # implementation, decode only.
• CyanDelta: Use of Xdelta3 patches for CyanogenMod ROM updates.

See also

• Delta coding

Individual evidence

1. ↑ CiteSeerX - Data Compression Using Long Common Strings
2. ↑ http://code.google.com/p/open-vcdiff/
3. ↑ http://www2.research.att.com/~astopen/man/man1/vczip.html
4. ↑ http://code.google.com/p/diffable/
5. ↑ Archived copy ( Memento of the original dated May 7, 2014 in the web archive archive.today ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. 
6. ↑ http://code.google.com/p/j-vcdiff/
7. ↑ http://www.yoda.arachsys.com/csharp/miscutil/
8. ↑ Archived copy ( Memento of the original from July 7, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.