pp_dtw_align — Dynamic time warping spectral alignment¶
Group: Signal transforms · C ABI: n4m_transform_dtw_align_*
Description¶
Dynamic-time-warping alignment to a fixed-length reference.
Parameters¶
Name |
Type |
Default |
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API and bindings¶
C ABI (ABI 2): n4m_transform_dtw_align_create · n4m_transform_dtw_align_destroy · n4m_transform_dtw_align_fit · n4m_transform_dtw_align_is_fitted · n4m_transform_dtw_align_transform. Use the linked public header for the exact signature, configuration, and result handles.
Python (verified public re-export):
from n4m.transform.alignment import DynamicTimeWarpingAlignment
Source signature: DynamicTimeWarpingAlignment(reference = None).
R: no current source-verified entry point was found for this catalog method.
MATLAB / Octave: no current source-verified entry point was found for this catalog method.
Explanations¶
Bibliographic source¶
Sakoe & Chiba (1978), Dynamic programming algorithm optimization for spoken word recognition, IEEE TASSP 26, 43–49, https://doi.org/10.1109/TASSP.1978.1163055.
Mathematical principle¶
A dynamic program finds a minimum-cost monotone path through pairwise sample/reference distances. The path maps local stretches and compressions to the reference grid; multiple matched input points are aggregated to keep a fixed output length.
Appropriate uses¶
Aligning spectra with nonlinear local wavelength shifts that cannot be represented by one global offset.
Limits and validation¶
Unconstrained DTW can align unrelated bands and is quadratic in spectrum length. Amplitude differences affect the path, and the result depends on the reference.
Implementation¶
n4m.transform.alignment.DynamicTimeWarpingAlignment wraps n4m_transform_dtw_align_*; the native path computation is in cpp/src/c_api/c_api_advanced.cpp.
The ABI-2 implementation is the n4m_transform_dtw_align_* lifecycle in libn4m.
Sources and provenance¶
https://doi.org/10.1109/TASSP.1978.1163055; https://github.com/GBeurier/nirs4all-methods/blob/main/cpp/src/c_api/c_api_advanced.cpp
See also: methods index · interactive dashboard