k2py
Python bindings for k2
Features
- Efficient Streaming Decoding: OnlineDenseIntersecter for real-time forced alignment
- Memory-Bounded Streaming:
decode_and_flush()keeps memory at O(chunk) for arbitrarily long audio - Mixed Decode Modes: Combine
decode()anddecode_and_flush()for flush-every-N-chunks strategies - WebAssembly Support: Browser-side forced alignment via Emscripten (WASM32 + WASM64)
- Cross-Platform: Supports Linux, macOS, and Windows
- Python 3.10+: Compatible with modern Python versions
- Built with pybind11: Fast C++ bindings with minimal overhead
Installation
From PyPI
pip install k2py
Coexistence with k2
k2py can coexist with the k2 package. Both can be imported in any order:
import k2
import k2py # works fine
Usage
Basic Example
from k2py import OnlineDenseIntersecter, CreateFsaVecFromStr
import numpy as np
# Create FSA from string representation
fsa_str = "0 1 1 1.0\n1 2 2 1.0\n2"
result = CreateFsaVecFromStr(fsa_str, final_state=2)
# Initialize decoder
decoder = OnlineDenseIntersecter(
result["fsa"],
result["aux_labels"],
search_beam=20.0,
output_beam=8.0,
min_active_states=30,
max_active_states=10000
)
# Prepare acoustic scores (num_frames x vocab_size)
scores = np.random.randn(100, 50).astype(np.float32)
# Decode
lattice = decoder.DecodeWithArray(scores, return_lattice=True)
# Get final alignment result
alignment = decoder.Finish()
print(f"Token IDs: {alignment['token_ids']}")
print(f"Timestamps: {alignment['timestamps']}")
print(f"Durations: {alignment['durations']}")
Streaming with Memory-Bounded Flush
# For long audio: decode_and_flush() caps memory at O(chunk)
all_tokens = []
for chunk_scores in chunk_iterator(scores, chunk_size=1000):
tokens, labels = decoder.decode_and_flush(chunk_scores)
all_tokens.extend(tokens)
# Get any remaining tokens
final_tokens, final_labels = decoder.finish()
all_tokens.extend(final_tokens[0])
WebAssembly
k2py also compiles to WebAssembly for browser-side forced alignment. See wasm/README.md for build instructions, API reference, and benchmarks.
1 maintainer
Metadata
1 maintainer
Release files for k2py 0.4.0
For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.
Built distributions (wheels)
| File | Reset | |||
|---|---|---|---|---|
| k2py-0.4.0-cp314-cp314-win_amd64.whl | CPython 3.14 | CPython 3.14 | Windows x86-64 | Details |
| k2py-0.4.0-cp314-cp314-manylinux_2_27_x86_64.manylinux_2_28_x86_64.whl | CPython 3.14 | CPython 3.14 | Linux glibc 2.27+ x86-64, Linux glibc 2.28+ x86-64 | Details |
| k2py-0.4.0-cp314-cp314-macosx_15_0_arm64.whl | CPython 3.14 | CPython 3.14 | macOS 15.0+ ARM64 | Details |
| k2py-0.4.0-cp313-cp313-win_amd64.whl | CPython 3.13 | CPython 3.13 | Windows x86-64 | Details |
| k2py-0.4.0-cp313-cp313-manylinux_2_27_x86_64.manylinux_2_28_x86_64.whl | CPython 3.13 | CPython 3.13 | Linux glibc 2.28+ x86-64, Linux glibc 2.27+ x86-64 | Details |
| k2py-0.4.0-cp313-cp313-macosx_15_0_arm64.whl | CPython 3.13 | CPython 3.13 | macOS 15.0+ ARM64 | Details |
| k2py-0.4.0-cp312-cp312-win_amd64.whl | CPython 3.12 | CPython 3.12 | Windows x86-64 | Details |
| k2py-0.4.0-cp312-cp312-manylinux_2_27_x86_64.manylinux_2_28_x86_64.whl | CPython 3.12 | CPython 3.12 | Linux glibc 2.28+ x86-64, Linux glibc 2.27+ x86-64 | Details |
| k2py-0.4.0-cp312-cp312-macosx_15_0_arm64.whl | CPython 3.12 | CPython 3.12 | macOS 15.0+ ARM64 | Details |
| k2py-0.4.0-cp311-cp311-win_amd64.whl | CPython 3.11 | CPython 3.11 | Windows x86-64 | Details |
| k2py-0.4.0-cp311-cp311-manylinux_2_27_x86_64.manylinux_2_28_x86_64.whl | CPython 3.11 | CPython 3.11 | Linux glibc 2.28+ x86-64, Linux glibc 2.27+ x86-64 | Details |
| k2py-0.4.0-cp311-cp311-macosx_15_0_arm64.whl | CPython 3.11 | CPython 3.11 | macOS 15.0+ ARM64 | Details |
| k2py-0.4.0-cp310-cp310-win_amd64.whl | CPython 3.10 | CPython 3.10 | Windows x86-64 | Details |
| k2py-0.4.0-cp310-cp310-manylinux_2_27_x86_64.manylinux_2_28_x86_64.whl | CPython 3.10 | CPython 3.10 | Linux glibc 2.28+ x86-64, Linux glibc 2.27+ x86-64 | Details |
| k2py-0.4.0-cp310-cp310-macosx_15_0_arm64.whl | CPython 3.10 | CPython 3.10 | macOS 15.0+ ARM64 | Details |
Total release size: 5.6 MB
Release files / k2py-0.4.0-cp314-cp314-win_amd64.whl
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