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git-svn-id: svn+ssh://svn.code.sf.net/p/cmusphinx/code/trunk/SphinxTrain@9613 94700074-3cef-4d97-a70e-9c8c206c02f5
49 lines
1.5 KiB
Python
49 lines
1.5 KiB
Python
# Copyright (c) 2006 Carnegie Mellon University
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#
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# You may copy and modify this freely under the same terms as
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# Sphinx-III
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"""Compute Sphinx-II 4-stream features.
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This module provides a compute() function to compute 52-dimensional
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4-stream features consisting of cepstra and their first and second
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time derivatives, and the C0 values. This is the default feature type
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used for PocketSphinx and Sphinx-II semi-continuous acoustic models.
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"""
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__author__ = "David Huggins-Daines <dhuggins@cs.cmu.edu>"
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__version__ = "$Revision$"
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from numpy import zeros, concatenate
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def compute(mfcc):
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"""Compute 52-dimensional 4-stream features consisting of cepstra
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and their first and second time derivatives, and the C0 values."""
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r, c = mfcc.shape
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# Pad the features to compute dcep, ddcep
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pad = concatenate((zeros((5,c)), mfcc, zeros((5,c))))
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# Now create the output array
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feat = (zeros((r, c-1),'d'),
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zeros((r, (c-1)*2),'d'),
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zeros((r, 3),'d'),
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zeros((r, c-1),'d'))
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# cep (without C0)
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feat[0][:] = mfcc[:,1:]
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# dcep = mfc[2] - mfc[-2] : mfc[4] - mfc[-4]
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feat[1][:, 0:12] = (pad[7:-3,1:] - pad[3:-7,1:])
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feat[1][:, 12:] = (pad[9:-1,1:] - pad[1:-9,1:])
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# ddcep = (mfc[3] - mfc[-1]) - (mfc[1] - mfc[-3])
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feat[3][:] = (pad[8:-2,1:] - pad[4:-6,1:]) - (pad[6:-4,1:] - pad[2:-8,1:])
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# pow = C0,D0,DD0
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feat[2][:,0] = mfcc[:,0]
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feat[2][:,1] = (pad[7:-3,0] - pad[3:-7,0])
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feat[2][:,2] = (pad[8:-2,0] - pad[4:-6,0]) - (pad[6:-4,0] - pad[2:-8,0])
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return feat
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