ndspy

Discord GitHub PyPI License: GNU GPL 3.0

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 [1].
  • 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 [2]. 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. Note that Python doesn’t support the Nintendo DS itself; ndspy is intended to be used on your PC.

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!

Note

If you plan to use ndspy to work with sound data and you aren’t yet familiar with SDAT files, consider reading the appendix explaining how they’re structured first.

[1]That is, if it’s arranged in the way that files in that format usually are. Although it’s often possible to arrange a file in many different ways and still have it be valid, ndspy only aims for byte-for-byte output accuracy with files that are arranged in the most common way.
[2]Unfortunately, the command-line tools are sorely lacking in both substance and documentation at the moment. I hope to improve these in the not-too-distant future!

A few examples of ndspy in action

Create a BMG file containing message strings:

>>> import ndspy.bmg
>>> message1 = ndspy.bmg.Message(b'', ['Open your eyes...'])
>>> message2 = ndspy.bmg.Message(b'', ['Wake up, Link...'])
>>> bmg = ndspy.bmg.BMG.fromMessages([message1, message2])
>>> bmg.save()
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\x04\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 song.events:
...     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
>>> rom = ndspy.rom.NintendoDSRom.fromFile('nsmb.nds')
>>> for i, file in enumerate(rom.files):
...     if file.startswith(b'BMD0'):
...         print(rom.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
>>>

Misconceptions

Still a little confused about what exactly ndspy is or what it’s capable of? This section will try to answer some questions you may have.

  • ndspy is a library, not a program. To use ndspy, you have to write your own Python code; ndspy is essentially a tool your code can use. This may sound daunting – especially if you’re not very familiar with Python – but the Tutorials walk you through this process step-by-step for some common tasks. In the future, I plan to add some command-line and maybe even GUI tools powered by ndspy, but until then, this is how you use it.

  • ndspy runs on your PC, not on the Nintendo DS itself. You use it to create and modify game files, which can then be run on the console. DS games have to be written in a compiled language such as C or C++ to have any hope of being efficient; Python will never be a serious option there, unfortunately.

  • ndspy doesn’t support every type of file used in every DS game. In fact, for any given game, it’s likely that the majority of the game’s files won’t be supported by ndspy. There’s a huge amount of variety in video game file formats, and it would be impossible to support them all. ndspy focuses on file formats used in many games, especially first-party ones. Support for formats that are specific to a particular game would best belong in a separate Python library instead.

    That said, certain parts of ndspy (such as its support for ROM files and raw texture data) have to do with the console’s hardware rather than its software, and thus should be relevant to most or all games.

Installation

ndspy requires Python 3.6 or newer to run. CPython (the reference implementation of Python) and PyPy are both supported. Python 2, though, 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.

Support

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.

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!

Versioning

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.

Contents

Credits

ndspy was written by RoadrunnerWMC, using information from many, many sources. In alphabetical order:

Thank you to everyone who wrote these sources!

Indices and tables

Todo

It’d be great to add an example or two to the top of every module.

Functions for loading/saving BMG to/from wbmgt format?

The tools need a lot of work, and documentation.

Automated testing.

Write tutorials.

Try running the SSEQ/SSAR parser on all ROMs to identify issues.

ROM secure area en/decryption, ported from ndstool

https://en.wikipedia.org/wiki/Sample-based_synthesis#Multisampling
Maybe rename regional instruments to that? And definitely link to that.

Unit testing:

To test a class that parses a file (aka the most common case), just make these tests:

  • one file that contains everything the file would normally contain (e.g. not including unreferenced SBNK inst’s)
  • one empty file
  • as many interesting edge cases as you can think of (e.g. unreferenced SBNK inst’s)

Use ndspy to build these test case files.

Additionally, save the code used to build the files, and use that as a second set of tests: does running this code produce the expected output files again?