created_at2022-04-30 04:36:11.768106
updated_at2023-05-20 09:37:03.972943
descriptionA library for reading and writing MSD files.
Anders Evensen (Anders429)




GitHub Workflow Status MSRV License

A library for reading and writing MSD files.


Reading and writing of MSD files is done using serde, a library for generic serialization and deserialization. It will work with any types that implement the Serialize and Deserialize traits.


use std::collections::HashMap;

fn main() {
    let mut map: HashMap<String, usize> = HashMap::new();
    map.insert("foo".to_owned(), 1);
    map.insert("bar".to_owned(), 2);

    // Serialize the map into a byte buffer.
    let serialized = msd::to_bytes(&map).unwrap();

    // Deserialize back into a map again.
    let deserialized = msd::from_bytes(&serialized).unwrap();

    assert_eq!(map, deserialized); 

Unrepresentable Types

Not all serde types can be represented in MSD format. Some compound types cannot be encoded due to the ambiguity that would arise when decoding them. Specifically, these unrepresentable serde types are:

  • tuple or tuple_struct containing option.
  • tuple or tuple_struct containing seq.
  • tuple or tuple_struct containing map.
  • tuple or tuple_struct containing struct.
  • struct containing another struct as a field value.
  • seq containing option.
  • seq containing another seq as an element.

Additionally, this library cannot deserialize types that are intended to be deserialized as self-describing, and both struct fields and enum variants must be deserialized as identifiers. See serde's Deserializer documentation for more details.

About MSD Files

MSD is a configuration file format that has been in use since the late 90s. It has mainly seen usage in rhythm dance games such as Stepmania and Dancing With Intensity, but it is suitable to be used in many other contexts. MSD files benefit from being human-readable and easily modifiable.


While the MSD file format has never been formally specified, the format has been informally defined as any number of tags paired with an optional number of parameters in the following format: #TAG:PARAM0:PARAM1:PARAM2;. Tags and parameters can be any sequence of bytes, with the requirement that :, ;, #, and \ bytes are escaped.

Comments may be made with a leading //. Any pair of // that are not intended to create a comment should be escaped. Note that while this library can parse MSD files with comments, it cannot write comments.

Some informal usages of MSD have allowed multiple parameter lists for a single tag, most notably Dancing With Intensity's .dwi files (which is written with MSD format) with its #BACKGROUND tag. This library is equipped to read and write these types of tags as well, interpreting them as the serde map data type.


The first known use of the MSD format is from the rhythm dance game DDR'99 (DDR here standing for "Delight Delight Reduplication"). The earliest known specification of the .msd files used is version 2.0β1. Note that .msd files are not necessarily the same as what is commonly referred to as an "MSD File"; .msd files often contain specific tags, whereas an "MSD file" is any file that follows the general MSD tag-parameter structure (See also Stepmania's definition of an MSD file).

As for what MSD originally stood for, no one seems to know for sure. The best guess is likely "Musical Score Data", but there isn't a concrete source to back this up. Modern usages of the format simply refer to it as "MSD".

Minimum Supported Rust Version

This crate is guaranteed to compile on stable rustc 1.58.0 and up.


This project is licensed under either of

at your option.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Commit count: 188

cargo fmt