--- name: "bzz" section: "1" platform: "linux" package: "djvulibre" version: "3.5.30.1-1" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/bzz" --- # bzz(1) DjVu general purpose compression utility. ## NAME bzz - DjVu general purpose compression utility. ## SYNOPSIS ## Encoding: **bzz -e***\[blocksize\]* *inputfile* *outputfile* ## Decoding: **bzz -d** *inputfile* *outputfile* ## DESCRIPTION The first form of the command line (option **-e**) compresses the data from file *inputfile* and writes the compressed data into *outputfile*. The second form of the command line (option **-d**) decompressed file *inputfile* and writes the output to *outputfile*. ## OPTIONS - **-d** Decoding mode. - **-e***\[blocksize\]* Encoding mode. The optional argument *blocksize* specifies the size of the input file blocks processed by the Burrows-Wheeler transform expressed in kilobytes. The default block sizes is 2048 KB. The maximal block size is 4096 KB. Specifying a larger block size usually produces higher compression ratios and increases the memory requirements of both the encoder and decoder. It is useless to specify a block size that is larger than the input file. ## ALGORITHMS The Burrows-Wheeler transform is performed using a combination of the Karp-Miller-Rosenberg and the Bentley-Sedgewick algorithms. This is comparable to (Sadakane, DCC 98) with a slightly more flexible ranking scheme. Symbols are then ordered according to a running estimate of their occurrence frequencies. The symbol ranks are then coded using a simple fixed tree and the ZP binary adaptive coder (Bottou, DCC 98). The Burrows-Wheeler transform is also used in the well known compressor **bzip2**. The originality of **bzz** is the use of the ZP adaptive coder. The adaptation noise can cost up to 5 percent in file size, but this penalty is usually offset by the benefits of adaptation. ## PERFORMANCE The following table shows comparative results (in bits per character) on the Canterbury Corpus ( **http://corpus.canterbury.ac.nz** ). The very good **bzz** performance on the spreadsheet file *excl* puts the weighted average ahead of much more sophisticated compressors such as **fsmx**. | | | | | | | | | | | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | Compression performance | | | text | fax | csrc | excl | sprc | tech | poem | html | lisp | man | play | Weighted | Average | | compress | 3.27 | 0.97 | 3.56 | 2.41 | 4.21 | 3.06 | 3.38 | 3.68 | 3.90 | 4.43 | 3.51 | 2.55 | 3.31 | | gzip -9 | 2.85 | 0.82 | 2.24 | 1.63 | 2.67 | 2.71 | 3.23 | 2.59 | 2.65 | 3.31 | 3.12 | 2.08 | 2.53 | | bzip2 -9 | 2.27 | 0.78 | 2.18 | 1.01 | 2.70 | 2.02 | 2.42 | 2.48 | 2.79 | 3.33 | 2.53 | 1.54 | 2.23 | | ppmd | 2.31 | 0.99 | 2.11 | 1.08 | 2.68 | 2.19 | 2.48 | 2.38 | 2.43 | 3.00 | 2.53 | 1.65 | 2.20 | | fsmx | **2.10** | 0.79 | **1.89** | 1.48 | **2.52** | **1.84** | **2.21** | **2.24** | **2.29** | **2.91** | **2.35** | 1.63 | **2.06** | | **bzz** | 2.25 | **0.76** | 2.13 | **0.78** | 2.67 | 2.00 | 2.40 | 2.52 | 2.60 | 3.19 | 2.52 | **1.44** | 2.16 | Note that DjVu contributors have several entries in this table. Program **compress** was written some time ago by Joe Orost. Program **ppmd** is an improvement of the PPM-C method invented by Paul Howard. ## CREDITS Program **bzz** was written by Léon Bottou \ and was then improved by Andrei Erofeev \, Bill Riemers \ and many others. ## SEE ALSO [**djvu**(1)](/djvu/1.md), [**compress**(1)](/compress/1.md), [**gzip**(1)](/gzip/1.md), [**bzip2**(1)](/bzip2/1.md)