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Introduction

Autodesk Maya, the modelling and animation program used widely in film, television and games, saves its scenes in two forms. Maya Binary (.mb) is the default; Maya ASCII (.ma) is the same scene written as text. Both hold the whole dependency graph: every node, from meshes and transforms to deformers, shaders and animation curves, with its attributes and the connections between nodes.

Studios often prefer Maya ASCII because it can be read, searched, compared and repaired in a text editor. Neither form is documented as a file format, and outside Maya scenes are exchanged as FBX, Alembic or USD.

Structure

A Maya ASCII file is a script in MEL, Maya’s command language. It begins with a comment such as //Maya ASCII 2024 scene, then requires lines naming the Maya version and plugins, currentUnit and fileInfo. The scene is rebuilt by running the commands that follow: createNode makes each node, setAttr sets its values and connectAttr joins them.

//Maya ASCII 2024 scene
requires maya "2024";
currentUnit -l centimeter -a degree -t film;
createNode transform -n "pCube1";
createNode mesh -n "pCubeShape1" -p "pCube1";
createNode polyCube -n "polyCube1";
connectAttr "polyCube1.out" "pCubeShape1.i";

A Maya Binary file holds the same information in an IFF-style layout of tagged, nested chunks. It starts with the group tag FOR4, or FOR8 in files written with 64-bit chunk sizes, followed by the form type Maya.

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