There's quite a lot of retro modern LZ activity too! LZ turns out to be amazing on old machines, often only a couple times slower than a block copy. Optimal compressors and control over the algorithm have led to some very tight demos.

https://www.brutaldeluxe.fr/products/crossdevtools/lz4/index... LZ4 Data Compression - a rather long and in-depth article looking at LZ4 on the 65816 for the Apple IIgs with a decompressor that exploits that processor's block copy.

https://github.com/emmanuel-marty/lzsa - LZSA - a LZ4-like modern LZ that's more efficient both in speed and compression to LZ4 (at least on the 8 bitters it targets) - includes a neat chart of speed/compression trade-offs on a ZX Spectrum with a variety of algorithms

Discussed at the time:

Modern LZ Compression - https://news.ycombinator.com/item?id=19064791 - Feb 2019 (4 comments)

"Managing Gigabytes" by Witten et al is _the_ book that got me into the field of compression back in the day. Granted, it’s a bit dated now as there’s been a lot of progress in the field, but I’d still heartily recommend it to newcomers.

Only partly related, since it deals with a specific type of data (English language Wikipedia), some of you might enjoy reading about the Hutter Prize: https://en.wikipedia.org/wiki/Hutter_Prize

Does anyone have recommendations for learning the xz format? Particularly as used by the ZIM archival format: https://en.wikipedia.org/wiki/ZIM_(file_format)

> First, we just shorten any symbols that are longer than our maximum code length — 11 — to that value. This means that our tree will no longer be a Huffman tree, so we need to do a fixup pass to redistribute the error we've introduced.

This can in fact be solved directly and optimally: https://en.wikipedia.org/wiki/Package-merge_algorithm ; https://en.wikipedia.org/wiki/Huffman_coding#Length-limited_...

I just made a huffman encoder on the c64, for fun. I need understand how you go from the variable length codes of huffman, to suddenly fixed lenght codes, because you don't want the codes to be above a certain length. hmm...

I wonder if LZ would still be standard, if not for the inertia of gzip/zip? There are surely better and comparably fast algorithms (paq, ppm, etc.)

I had to implement recently an oldstyle lz77 en/decoder to handle an old fileformat, and it was surprisingly simple. Even the encoder

"Modern", but uses Huffman coding? No LZ implementation aiming for high compression in the last decade has used Huffman.