feature-plp.cc
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// feat/feature-plp.cc
// Copyright 2009-2011 Petr Motlicek; Karel Vesely
// 2016 Johns Hopkins University (author: Daniel Povey)
// See ../../COPYING for clarification regarding multiple authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
// MERCHANTABLITY OR NON-INFRINGEMENT.
// See the Apache 2 License for the specific language governing permissions and
// limitations under the License.
#include "feat/feature-plp.h"
namespace kaldi {
PlpComputer::PlpComputer(const PlpOptions &opts):
opts_(opts), srfft_(NULL),
mel_energies_duplicated_(opts_.mel_opts.num_bins + 2, kUndefined),
autocorr_coeffs_(opts_.lpc_order + 1, kUndefined),
lpc_coeffs_(opts_.lpc_order, kUndefined),
raw_cepstrum_(opts_.lpc_order, kUndefined) {
if (opts.cepstral_lifter != 0.0) {
lifter_coeffs_.Resize(opts.num_ceps);
ComputeLifterCoeffs(opts.cepstral_lifter, &lifter_coeffs_);
}
InitIdftBases(opts_.lpc_order + 1, opts_.mel_opts.num_bins + 2,
&idft_bases_);
if (opts.energy_floor > 0.0)
log_energy_floor_ = Log(opts.energy_floor);
int32 padded_window_size = opts.frame_opts.PaddedWindowSize();
if ((padded_window_size & (padded_window_size-1)) == 0) // Is a power of two...
srfft_ = new SplitRadixRealFft<BaseFloat>(padded_window_size);
// We'll definitely need the filterbanks info for VTLN warping factor 1.0.
// [note: this call caches it.]
GetMelBanks(1.0);
}
PlpComputer::PlpComputer(const PlpComputer &other):
opts_(other.opts_), lifter_coeffs_(other.lifter_coeffs_),
idft_bases_(other.idft_bases_), log_energy_floor_(other.log_energy_floor_),
mel_banks_(other.mel_banks_), equal_loudness_(other.equal_loudness_),
srfft_(NULL),
mel_energies_duplicated_(opts_.mel_opts.num_bins + 2, kUndefined),
autocorr_coeffs_(opts_.lpc_order + 1, kUndefined),
lpc_coeffs_(opts_.lpc_order, kUndefined),
raw_cepstrum_(opts_.lpc_order, kUndefined) {
for (std::map<BaseFloat, MelBanks*>::iterator iter = mel_banks_.begin();
iter != mel_banks_.end(); ++iter)
iter->second = new MelBanks(*(iter->second));
for (std::map<BaseFloat, Vector<BaseFloat>*>::iterator
iter = equal_loudness_.begin();
iter != equal_loudness_.end(); ++iter)
iter->second = new Vector<BaseFloat>(*(iter->second));
if (other.srfft_ != NULL)
srfft_ = new SplitRadixRealFft<BaseFloat>(*(other.srfft_));
}
PlpComputer::~PlpComputer() {
for (std::map<BaseFloat, MelBanks*>::iterator iter = mel_banks_.begin();
iter != mel_banks_.end(); ++iter)
delete iter->second;
for (std::map<BaseFloat, Vector<BaseFloat>* >::iterator
iter = equal_loudness_.begin();
iter != equal_loudness_.end(); ++iter)
delete iter->second;
delete srfft_;
}
const MelBanks *PlpComputer::GetMelBanks(BaseFloat vtln_warp) {
MelBanks *this_mel_banks = NULL;
std::map<BaseFloat, MelBanks*>::iterator iter = mel_banks_.find(vtln_warp);
if (iter == mel_banks_.end()) {
this_mel_banks = new MelBanks(opts_.mel_opts,
opts_.frame_opts,
vtln_warp);
mel_banks_[vtln_warp] = this_mel_banks;
} else {
this_mel_banks = iter->second;
}
return this_mel_banks;
}
const Vector<BaseFloat> *PlpComputer::GetEqualLoudness(BaseFloat vtln_warp) {
const MelBanks *this_mel_banks = GetMelBanks(vtln_warp);
Vector<BaseFloat> *ans = NULL;
std::map<BaseFloat, Vector<BaseFloat>*>::iterator iter
= equal_loudness_.find(vtln_warp);
if (iter == equal_loudness_.end()) {
ans = new Vector<BaseFloat>;
GetEqualLoudnessVector(*this_mel_banks, ans);
equal_loudness_[vtln_warp] = ans;
} else {
ans = iter->second;
}
return ans;
}
void PlpComputer::Compute(BaseFloat signal_raw_log_energy,
BaseFloat vtln_warp,
VectorBase<BaseFloat> *signal_frame,
VectorBase<BaseFloat> *feature) {
KALDI_ASSERT(signal_frame->Dim() == opts_.frame_opts.PaddedWindowSize() &&
feature->Dim() == this->Dim());
const MelBanks &mel_banks = *GetMelBanks(vtln_warp);
const Vector<BaseFloat> &equal_loudness = *GetEqualLoudness(vtln_warp);
KALDI_ASSERT(opts_.num_ceps <= opts_.lpc_order+1); // our num-ceps includes C0.
if (opts_.use_energy && !opts_.raw_energy)
signal_raw_log_energy = Log(std::max<BaseFloat>(VecVec(*signal_frame, *signal_frame),
std::numeric_limits<float>::min()));
if (srfft_ != NULL) // Compute FFT using split-radix algorithm.
srfft_->Compute(signal_frame->Data(), true);
else // An alternative algorithm that works for non-powers-of-two.
RealFft(signal_frame, true);
// Convert the FFT into a power spectrum.
ComputePowerSpectrum(signal_frame); // elements 0 ... signal_frame->Dim()/2
SubVector<BaseFloat> power_spectrum(*signal_frame,
0, signal_frame->Dim() / 2 + 1);
int32 num_mel_bins = opts_.mel_opts.num_bins;
SubVector<BaseFloat> mel_energies(mel_energies_duplicated_, 1, num_mel_bins);
mel_banks.Compute(power_spectrum, &mel_energies);
mel_energies.MulElements(equal_loudness);
mel_energies.ApplyPow(opts_.compress_factor);
// duplicate first and last elements
mel_energies_duplicated_(0) = mel_energies_duplicated_(1);
mel_energies_duplicated_(num_mel_bins + 1) =
mel_energies_duplicated_(num_mel_bins);
autocorr_coeffs_.SetZero(); // In case of NaNs or infs
autocorr_coeffs_.AddMatVec(1.0, idft_bases_, kNoTrans,
mel_energies_duplicated_, 0.0);
BaseFloat residual_log_energy = ComputeLpc(autocorr_coeffs_, &lpc_coeffs_);
residual_log_energy = std::max<BaseFloat>(residual_log_energy,
std::numeric_limits<float>::min());
Lpc2Cepstrum(opts_.lpc_order, lpc_coeffs_.Data(), raw_cepstrum_.Data());
feature->Range(1, opts_.num_ceps - 1).CopyFromVec(
raw_cepstrum_.Range(0, opts_.num_ceps - 1));
(*feature)(0) = residual_log_energy;
if (opts_.cepstral_lifter != 0.0)
feature->MulElements(lifter_coeffs_);
if (opts_.cepstral_scale != 1.0)
feature->Scale(opts_.cepstral_scale);
if (opts_.use_energy) {
if (opts_.energy_floor > 0.0 && signal_raw_log_energy < log_energy_floor_)
signal_raw_log_energy = log_energy_floor_;
(*feature)(0) = signal_raw_log_energy;
}
if (opts_.htk_compat) { // reorder the features.
BaseFloat log_energy = (*feature)(0);
for (int32 i = 0; i < opts_.num_ceps-1; i++)
(*feature)(i) = (*feature)(i+1);
(*feature)(opts_.num_ceps-1) = log_energy;
}
}
} // namespace kaldi