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Python library that can help you read, modify and create many types of files used in Nintendo DS games.

Project description


ndspy ("en-dee-ESS-pie") is a Python library and suite of command-line tools that can help you read, modify and create many types of files used in Nintendo DS games.

ndspy follows a few key design principles:

  • Accuracy: ndspy should be able to open and resave any supported file with byte-for-byte accuracy if it's in its canonical format.
  • Flexibility: ndspy should be able to read any valid file in a format it supports. In cases where there's a high chance it will be unable to fully interpret some especially complex part of a file, it should still be useful for editing the other parts.
  • Semantic: ndspy's APIs should closely match the semantics of file structures while hiding their binary-level details.

ndspy provides both a Python API and a set of simple command-line tools that make use of it. The command-line tools let you convert files to and from binary formats without having to write any Python code yourself. The API is suitable for use in applications written in Python, and in scripts to do more complex tasks than the command-line tools are capable of.

As ndspy is written in pure Python, it is cross-platform and should run on all platforms Python supports.

Interested? Read on to see some examples, or check the API Reference to see the documentation for a specific module. When you're ready to install, head over to the Installation section!

A few examples of ndspy in action

Create a BMG file containing message strings:

>>> import ndspy.bmg
>>> message1 = ndspy.bmg.Message(0, ['Open your eyes...'])
>>> message2 = ndspy.bmg.Message(0, ['Wake up, Link...'])
>>> bmg = ndspy.bmg.BMG.fromMessages([message1, message2])
b'MESGbmg1\xa0\x00\x00\x00\x02\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00INF1 \x00\x00\x00\x02\x00\x08\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00&\x00\x00\x00\x00\x00\x00\x00DAT1`\x00\x00\x00\x00\x00O\x00p\x00e\x00n\x00 \x00y\x00o\x00u\x00r\x00 \x00e\x00y\x00e\x00s\x00.\x00.\x00.\x00\x00\x00W\x00a\x00k\x00e\x00 \x00u\x00p\x00,\x00 \x00L\x00i\x00n\x00k\x00.\x00.\x00.\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'

Change all notes in a SSEQ sequenced music file to middle C, similar to this song:

>>> import ndspy.soundSequence
>>> song = ndspy.soundSequence.SSEQ.fromFile('never-gonna-give-you-up.sseq')
>>> song.parse()
>>> for event in
...     if isinstance(event, ndspy.soundSequence.NoteSequenceEvent):
...         event.pitch = 60
>>> song.saveToFile('never-gonna-give-you-up-but-all-the-notes-are-c.sseq')

Compress and decompress data using the LZ10 compression format:

>>> import ndspy.lz10
>>> compressed = ndspy.lz10.compress(b'This is some data to compress')
>>> compressed
b'\x10\x1d\x00\x00\x04This \x00\x02so\x00me data \x00to compr\x00ess\x00\x00\x00\x00\x00'
>>> ndspy.lz10.decompress(compressed)
b'This is some data to compress'

Search for all files starting with a particular byte sequence in a ROM:

>>> import ndspy.rom
>>> game = ndspy.rom.NintendoDSRom.fromFile('game.nds')
>>> for i, file in enumerate(game.files):
...     if file.startswith(b'BMD0'):
...         print(game.filenames[i] + ' is a NSBMD model')
demo/end_kp.nsbmd is a NSBMD model
demo/staffroll.nsbmd is a NSBMD model
demo/staffroll_back.nsbmd is a NSBMD model
enemy/A_jiku.nsbmd is a NSBMD model
enemy/all_goal_flag.nsbmd is a NSBMD model
map/world7.nsbmd is a NSBMD model
map/world8.nsbmd is a NSBMD model


ndspy requires Python 3.6 or newer to run. Python 2 is not supported at all.

The easiest way to get the latest stable release of ndspy is through PyPI using pip.

pip is a command-line application, so you'll need to use the Windows command prompt or bash to do this. The exact command you need to enter depends on your operating system and the settings you chose when you installed Python. One of the following possibilities will probably work for you, though:

pip install ndspy

python3 -m pip install ndspy

py -3 -m pip install ndspy

If you want the very latest version of ndspy including features and bugfixes not yet in any official release, you can also download the code from the GitHub repository and install it manually. Note that crcmod is a required dependency.


ndspy's documentation is hosted on Read the Docs, and the documentation source code can be found in the docs/ folder in this repository. In addition to the API reference, there are also examples and tutorials to help you out!


I spent a long time writing the documentation for ndspy, so first please double-check that your question isn't already answered in the API reference or Tutorials sections in the documentation.

If that doesn't help, you can ask me (RoadrunnerWMC) your questions via the ndspy Discord server. I'll try to get back to you as quickly as I can!

If you think you've found a bug in ndspy, please file an issue on GitHub. Thanks!


ndspy follows semantic versioning to the best of my ability. If a tool claims to work with ndspy 1.0.2, it should also work with ndspy 1.2.0, but not necessarily 2.0.0. (Please note that not all of those version numbers actually exist!)

Undocumented modules are considered exempt from semantic versioning, and are subject to drastic changes at any time. This is also mentioned in the Undocumented APIs section of the documentation.

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