Concepts
Codecs
Entropy coders used per plane — Huffman, rANS, Identity, Zstd, Order-1 ScaleAC.
PTWM ships several plane codecs. The compressor trial-encodes each plane with every codec in the configured menu and keeps the smallest result — selection is per-plane, and no codec is the default.
Available Codecs
PTWM includes multiple entropy coders, dictionary coders, and specialized predictors. A detailed overview of each available codec, its optimal use-cases, and its theory of operation can be found in the Codecs section.
Dispatch
Each plane gets its own codec dispatch record in the .ptwmcontainer. The decoder reads the dispatch
record, allocates the per-codec state, and runs the inverse codec.