.BGCODE

Introduction

Binary G-code is a compact container for G-code, introduced by Prusa Research in 2023 for its printers and written by PrusaSlicer. It holds the same commands as a text G-code file, but compressed and split into blocks, with the print settings and preview images stored in their own blocks so a printer can show them without reading the whole file.

Files are often several times smaller than the text form, which speeds up transfer over a network. Prusa publishes the specification and a library, and the files can be converted back to plain G-code.

Structure

A binary G-code file starts with the four bytes GCDE, a version number and the type of checksum used. Blocks follow, each with a header giving its type, its compression and its sizes, then its parameters, its data and an optional CRC-32 checksum. Metadata blocks come first: printer metadata, thumbnails, print metadata and slicer metadata. The G-code itself follows in a series of blocks, compressed with Deflate or Heatshrink and optionally packed with MeatPack, which stores common G-code characters in fewer bits.

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