DEFLATE

File Format
Name	DEFLATE
Ontology	Electronic File Formats Compression DEFLATE
PRONOM	x-cmp/16
Wikidata ID	Q2712
Released	~1991

Deflate (stylized as DEFLATE, Deflate, or deflate) is a widely used lossless compression algorithm based on LZ77 with Huffman coding.

It was originally developed for use in PKZIP 2.x. For many software implementations that support creation or extraction of ZIP archive files, Deflate is the only compression algorithm supported.

There is a popular extension of Deflate known as zlib format, and the term "Deflate" often turns out to mean zlib. Formats that use Deflate without zlib include ZIP and gzip.

The term Inflate is sometimes used in conjunction with decompressing this format.

Format details

DEFLATE is a segmented format, with each segment using one of three compression schemes:

• 0: Non-compressed.
• 1: LZ77+Huffman, with predefined Huffman codebooks. Likely intended as a low-overhead scheme for small files.
• 2: LZ77+Huffman, static Huffman, with codebooks stored at the beginning of the segment.

Only non-compressed segments have a size limit.

See also

• ZIP
• zlib

Software

• zlib
• infgen - Deflate "disassembler"

See also zlib#Software, and ZIP#Software.

References

• RFC 1951: DEFLATE Compressed Data Format Specification version 1.3
• DEFLATE : Wikipedia
• Dissecting the GZIP format