@wdormann I still don't think though that algorithm modernity and "entropy" are connected: a compressor could become highly effective if it recognized large repeating chunks and assigned short codewords to them. I think what results in "noise-like" output is that compression is applied recursively, so the first-pass code tables are also compressed (see BLASTPASS :)). Maybe you could even do that with plain LZ until some point? I may be wrong, those uni lectures were a long time ago...