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NBSlim

Created for efficient implementation of logic redstone music by @kemiamu.

A tool for compressing Note Block Studio (.nbs) music files to efficiently store and play polyphonic music in Minecraft.

By discovering and compressing repetitive patterns in music, it significantly reduces the number of note blocks, allowing you to easily reuse existing note block structures in your builds, reduce repetitive work, and improve building efficiency.

Performance Optimisation

Core algorithms such as SIA, SIATEC, COSIATEC, and RecurSIA are re-implemented in Rust, achieving approximately 10x speedup, and provide Python bindings via a native Rust interface + lightweight wrapper. At runtime, it first tries to use the precompiled Rust implementation; if unavailable, it falls back to the Python implementation.

Key optimisation: The SIA algorithm is optimised from storing O(n²) point pairs to online HashMap aggregation, solving memory explosion issues for large NBS files.

Sweepline acceleration: In the SIATEC phase, you can enable sweepline_optimization=True (enabled by default) to use a sweepline‑based exact matching algorithm, providing further speedups for large datasets.

Due to the non‑uniqueness of pattern representation in SIA and non‑determinism of hash iteration, results from Python and Rust may occasionally differ by one TEC. This will be fixed in the future.

Core Algorithms

COSIATEC

COSIATEC (Compression SIATEC) is a greedy lossless compression algorithm. It first uses SIATEC to find all translationally repeatable patterns (translational equivalence classes) in the current set of music points, then selects the one with the highest compression ratio, removes the notes it covers from the dataset, and repeats the process until all notes are encoded. The output is a series of non-overlapping TECs, each represented by a pattern and a set of translation vectors. This algorithm is suitable for fast compression and effectively identifies obvious repeated segments.

RecurSIA

RecurSIA introduces recursion into COSIATEC. It recursively applies the same compression process to the pattern of each TEC, thereby discovering nested sub-pattern repetitions within the pattern. This enables RecurSIA to capture deeper musical structures (e.g., small motifs within phrases), achieving higher compression ratios than COSIATEC. Recursion depth can be controlled via the min_pattern_size parameter to balance compression effectiveness and computational overhead.

Requirements

pynbs>=1.1.0

To build from source, you also need:

• rust 1.95.0+
• maturin>=1.13,<2.0

Quick Start

Install with pip:

uv pip install nbslim

Or download the latest .whl file from the release:

uv pip install path/to/.whl

Read .nbs file

from nbslim.utils import notes_to_points
import pynbs

nbs_file_path = 'your_song.nbs'

song = pynbs.read(nbs_file_path)
points, note_dict = notes_to_points(song.notes)

Here note_dict stores the multiset mapping from (tick, pitch) to notes, used to recover note information unrelated to compression when writing back.

Compression

COSIATEC

from nbslim.sia_family import cosiatec_compress

# sweepline_optimization=True is enabled by default for faster execution
tecs = cosiatec_compress(points, restrict_dpitch_zero=True, sweepline_optimization=True)

RecurSIA

from nbslim.sia_family import recursive_cosiatec_compress

tecs = recursive_cosiatec_compress(points, restrict_dpitch_zero=True, min_pattern_size=2, sweepline_optimization=True)

View compression results

from nbslim.utils import compression_stats

print("Result:")
for i, tec in enumerate(tecs):
    print(f'TEC {i}')
    print(tec.summary(indent=2))
print()

stats = compression_stats(tecs, points)
print(f"Overall compression ratio: {stats['compression_ratio']:.3f} "
      f"(Original: {stats['original_count']}, Encoded units: {stats['encoded_units']})")

Rebuild and save as a new .nbs file

from nbslim.utils import tecs_to_nbs, merge_tecs

# Optional: merge all small TECs with coverage size <= 10 (default behaviour)
merged_tecs = merge_tecs(tecs)
new_file = tecs_to_nbs(merged_tecs, note_dict, song.header.__dict__)
new_file.save('.'.join(nbs_file_path.split('.')[:-1]) + '_rebuild.nbs')

tecs_to_nbs automatically handles layer allocation and song_layers settings without manual intervention.

Build Rust extension from source

git clone git@github.com:madSUNitist/NBSlim.git
cd nbslim
uv sync
uv tool install maturin
uv run maturin develop --release

API Reference

Core functions

Function	Description
find_mtps(dataset, restrict_dpitch_zero)	SIA algorithm, returns all maximal translatable patterns (vector → list of starting points)
build_tecs_from_mtps(dataset, restrict_dpitch_zero)	SIATEC algorithm, builds translational equivalence classes from MTPs
cosiatec_compress(dataset, restrict_dpitch_zero, sweepline_optimization)	COSIATEC greedy compression, returns a list of TECs covering the dataset
recursive_cosiatec_compress(dataset, restrict_dpitch_zero, min_pattern_size, sweepline_optimization)	RecurSIA recursive compression, supports nested patterns

All functions also have pure Python implementations with a _py suffix, used automatically when the Rust extension is unavailable. You can check the _rust_available flag to see if the Rust extension was loaded successfully.

Class

• TranslationalEquivalence: translational equivalence class
  • pattern: list of pattern points (sorted)
  • translators: set of translation vectors
  • sub_tecs: list of sub‑TECs from recursive compression
  • coverage: property, returns all points covered by this TEC
  • compression_ratio: property, compression ratio
  • compactness(points): returns compactness
  • summary(indent=0): returns a formatted recursive summary string

Utility functions

Function	Description
notes_to_points(notes)	Converts .nbs note list to (points, note_dict). points for compression, note_dict for reconstruction
tecs_to_nbs(tecs, note_dict, header)	Rebuilds an .nbs file object from compression results
merge_tecs(tecs, filter)	Merges all small TECs satisfying filter into one miscellaneous TEC (default filter: lambda tec: len(tec.coverage) <= 10)
compression_stats(tecs, original_points)	Computes compression statistics, returns a dict with original_count, encoded_units, and compression_ratio

References

1. Meredith, D., Lemström, K., & Wiggins, G. A. (2002). Algorithms for discovering repeated patterns in multidimensional representations of polyphonic music.
2. Meredith, D. (2013). COSIATEC and SIATECCompress: Pattern discovery by geometric compression.
3. Meredith, D. (2019). RecurSIA-RRT: Recursive translatable point-set pattern discovery with removal of redundant translators. arXiv preprint arXiv:1906.12286v2.