PaddleSpeech/speechx/examples/feat/feature-mfcc-test.cc

// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
//
// 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
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// feat/feature-mfcc-test.cc

// Copyright 2009-2011  Karel Vesely;  Petr Motlicek

// 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 <iostream>

#include "base/kaldi-math.h"
#include "feat/feature-mfcc.h"
#include "feat/wave-reader.h"
#include "matrix/kaldi-matrix-inl.h"

using namespace kaldi;


static void UnitTestReadWave() {
    std::cout << "=== UnitTestReadWave() ===\n";

    Vector<BaseFloat> v, v2;

    std::cout << "<<<=== Reading waveform\n";

    {
        std::ifstream is("test_data/test.wav", std::ios_base::binary);
        WaveData wave;
        wave.Read(is);
        const Matrix<BaseFloat> data(wave.Data());
        KALDI_ASSERT(data.NumRows() == 1);
        v.Resize(data.NumCols());
        v.CopyFromVec(data.Row(0));
    }

    std::cout
        << "<<<=== Reading Vector<BaseFloat> waveform, prepared by matlab\n";
    std::ifstream input("test_data/test_matlab.ascii");
    KALDI_ASSERT(input.good());
    v2.Read(input, false);
    input.close();

    std::cout
        << "<<<=== Comparing freshly read waveform to 'libsndfile' waveform\n";
    KALDI_ASSERT(v.Dim() == v2.Dim());
    for (int32 i = 0; i < v.Dim(); i++) {
        KALDI_ASSERT(v(i) == v2(i));
    }
    std::cout << "<<<=== Comparing done\n";

    // std::cout << "== The Waveform Samples == \n";
    // std::cout << v;

    std::cout << "Test passed :)\n\n";
}


/**
 */
static void UnitTestSimple() {
    std::cout << "=== UnitTestSimple() ===\n";

    Vector<BaseFloat> v(100000);
    Matrix<BaseFloat> m;

    // init with noise
    for (int32 i = 0; i < v.Dim(); i++) {
        v(i) = (abs(i * 433024253) % 65535) - (65535 / 2);
    }

    std::cout << "<<<=== Just make sure it runs... Nothing is compared\n";
    // the parametrization object
    MfccOptions op;
    // trying to have same opts as baseline.
    op.frame_opts.dither = 0.0;
    op.frame_opts.preemph_coeff = 0.0;
    op.frame_opts.window_type = "rectangular";
    op.frame_opts.remove_dc_offset = false;
    op.frame_opts.round_to_power_of_two = true;
    op.mel_opts.low_freq = 0.0;
    op.mel_opts.htk_mode = true;
    op.htk_compat = true;

    Mfcc mfcc(op);
    // use default parameters

    // compute mfccs.
    mfcc.Compute(v, 1.0, &m);

    // possibly dump
    //   std::cout << "== Output features == \n" << m;
    std::cout << "Test passed :)\n\n";
}


static void UnitTestHTKCompare1() {
    std::cout << "=== UnitTestHTKCompare1() ===\n";

    std::ifstream is("test_data/test.wav", std::ios_base::binary);
    WaveData wave;
    wave.Read(is);
    KALDI_ASSERT(wave.Data().NumRows() == 1);
    SubVector<BaseFloat> waveform(wave.Data(), 0);

    // read the HTK features
    Matrix<BaseFloat> htk_features;
    {
        std::ifstream is("test_data/test.wav.fea_htk.1",
                         std::ios::in | std::ios_base::binary);
        bool ans = ReadHtk(is, &htk_features, 0);
        KALDI_ASSERT(ans);
    }

    // use mfcc with default configuration...
    MfccOptions op;
    op.frame_opts.dither = 0.0;
    op.frame_opts.preemph_coeff = 0.0;
    op.frame_opts.window_type = "hamming";
    op.frame_opts.remove_dc_offset = false;
    op.frame_opts.round_to_power_of_two = true;
    op.mel_opts.low_freq = 0.0;
    op.mel_opts.htk_mode = true;
    op.htk_compat = true;
    op.use_energy = false;  // C0 not energy.

    Mfcc mfcc(op);

    // calculate kaldi features
    Matrix<BaseFloat> kaldi_raw_features;
    mfcc.Compute(waveform, 1.0, &kaldi_raw_features);

    DeltaFeaturesOptions delta_opts;
    Matrix<BaseFloat> kaldi_features;
    ComputeDeltas(delta_opts, kaldi_raw_features, &kaldi_features);

    // compare the results
    bool passed = true;
    int32 i_old = -1;
    KALDI_ASSERT(kaldi_features.NumRows() == htk_features.NumRows());
    KALDI_ASSERT(kaldi_features.NumCols() == htk_features.NumCols());
    // Ignore ends-- we make slightly different choices than
    // HTK about how to treat the deltas at the ends.
    for (int32 i = 10; i + 10 < kaldi_features.NumRows(); i++) {
        for (int32 j = 0; j < kaldi_features.NumCols(); j++) {
            BaseFloat a = kaldi_features(i, j), b = htk_features(i, j);
            if ((std::abs(b - a)) > 1.0) {  //<< TOLERANCE TO DIFFERENCES!!!!!
                // print the non-matching data only once per-line
                if (i_old != i) {
                    std::cout << "\n\n\n[HTK-row: " << i << "] "
                              << htk_features.Row(i) << "\n";
                    std::cout << "[Kaldi-row: " << i << "] "
                              << kaldi_features.Row(i) << "\n\n\n";
                    i_old = i;
                }
                // print indices of non-matching cells
                std::cout << "[" << i << ", " << j << "]";
                passed = false;
            }
        }
    }
    if (!passed) KALDI_ERR << "Test failed";

    // write the htk features for later inspection
    HtkHeader header = {
        kaldi_features.NumRows(),
        100000,  // 10ms
        static_cast<int16>(sizeof(float) * kaldi_features.NumCols()),
        021406  // MFCC_D_A_0
    };
    {
        std::ofstream os("tmp.test.wav.fea_kaldi.1",
                         std::ios::out | std::ios::binary);
        WriteHtk(os, kaldi_features, header);
    }

    std::cout << "Test passed :)\n\n";

    unlink("tmp.test.wav.fea_kaldi.1");
}


static void UnitTestHTKCompare2() {
    std::cout << "=== UnitTestHTKCompare2() ===\n";

    std::ifstream is("test_data/test.wav", std::ios_base::binary);
    WaveData wave;
    wave.Read(is);
    KALDI_ASSERT(wave.Data().NumRows() == 1);
    SubVector<BaseFloat> waveform(wave.Data(), 0);

    // read the HTK features
    Matrix<BaseFloat> htk_features;
    {
        std::ifstream is("test_data/test.wav.fea_htk.2",
                         std::ios::in | std::ios_base::binary);
        bool ans = ReadHtk(is, &htk_features, 0);
        KALDI_ASSERT(ans);
    }

    // use mfcc with default configuration...
    MfccOptions op;
    op.frame_opts.dither = 0.0;
    op.frame_opts.preemph_coeff = 0.0;
    op.frame_opts.window_type = "hamming";
    op.frame_opts.remove_dc_offset = false;
    op.frame_opts.round_to_power_of_two = true;
    op.mel_opts.low_freq = 0.0;
    op.mel_opts.htk_mode = true;
    op.htk_compat = true;
    op.use_energy = true;  // Use energy.

    Mfcc mfcc(op);

    // calculate kaldi features
    Matrix<BaseFloat> kaldi_raw_features;
    mfcc.Compute(waveform, 1.0, &kaldi_raw_features);

    DeltaFeaturesOptions delta_opts;
    Matrix<BaseFloat> kaldi_features;
    ComputeDeltas(delta_opts, kaldi_raw_features, &kaldi_features);

    // compare the results
    bool passed = true;
    int32 i_old = -1;
    KALDI_ASSERT(kaldi_features.NumRows() == htk_features.NumRows());
    KALDI_ASSERT(kaldi_features.NumCols() == htk_features.NumCols());
    // Ignore ends-- we make slightly different choices than
    // HTK about how to treat the deltas at the ends.
    for (int32 i = 10; i + 10 < kaldi_features.NumRows(); i++) {
        for (int32 j = 0; j < kaldi_features.NumCols(); j++) {
            BaseFloat a = kaldi_features(i, j), b = htk_features(i, j);
            if ((std::abs(b - a)) > 1.0) {  //<< TOLERANCE TO DIFFERENCES!!!!!
                // print the non-matching data only once per-line
                if (i_old != i) {
                    std::cout << "\n\n\n[HTK-row: " << i << "] "
                              << htk_features.Row(i) << "\n";
                    std::cout << "[Kaldi-row: " << i << "] "
                              << kaldi_features.Row(i) << "\n\n\n";
                    i_old = i;
                }
                // print indices of non-matching cells
                std::cout << "[" << i << ", " << j << "]";
                passed = false;
            }
        }
    }
    if (!passed) KALDI_ERR << "Test failed";

    // write the htk features for later inspection
    HtkHeader header = {
        kaldi_features.NumRows(),
        100000,  // 10ms
        static_cast<int16>(sizeof(float) * kaldi_features.NumCols()),
        021406  // MFCC_D_A_0
    };
    {
        std::ofstream os("tmp.test.wav.fea_kaldi.2",
                         std::ios::out | std::ios::binary);
        WriteHtk(os, kaldi_features, header);
    }

    std::cout << "Test passed :)\n\n";

    unlink("tmp.test.wav.fea_kaldi.2");
}


static void UnitTestHTKCompare3() {
    std::cout << "=== UnitTestHTKCompare3() ===\n";

    std::ifstream is("test_data/test.wav", std::ios_base::binary);
    WaveData wave;
    wave.Read(is);
    KALDI_ASSERT(wave.Data().NumRows() == 1);
    SubVector<BaseFloat> waveform(wave.Data(), 0);

    // read the HTK features
    Matrix<BaseFloat> htk_features;
    {
        std::ifstream is("test_data/test.wav.fea_htk.3",
                         std::ios::in | std::ios_base::binary);
        bool ans = ReadHtk(is, &htk_features, 0);
        KALDI_ASSERT(ans);
    }

    // use mfcc with default configuration...
    MfccOptions op;
    op.frame_opts.dither = 0.0;
    op.frame_opts.preemph_coeff = 0.0;
    op.frame_opts.window_type = "hamming";
    op.frame_opts.remove_dc_offset = false;
    op.frame_opts.round_to_power_of_two = true;
    op.htk_compat = true;
    op.use_energy = true;  // Use energy.
    op.mel_opts.low_freq = 20.0;
    // op.mel_opts.debug_mel = true;
    op.mel_opts.htk_mode = true;

    Mfcc mfcc(op);

    // calculate kaldi features
    Matrix<BaseFloat> kaldi_raw_features;
    mfcc.Compute(waveform, 1.0, &kaldi_raw_features);

    DeltaFeaturesOptions delta_opts;
    Matrix<BaseFloat> kaldi_features;
    ComputeDeltas(delta_opts, kaldi_raw_features, &kaldi_features);

    // compare the results
    bool passed = true;
    int32 i_old = -1;
    KALDI_ASSERT(kaldi_features.NumRows() == htk_features.NumRows());
    KALDI_ASSERT(kaldi_features.NumCols() == htk_features.NumCols());
    // Ignore ends-- we make slightly different choices than
    // HTK about how to treat the deltas at the ends.
    for (int32 i = 10; i + 10 < kaldi_features.NumRows(); i++) {
        for (int32 j = 0; j < kaldi_features.NumCols(); j++) {
            BaseFloat a = kaldi_features(i, j), b = htk_features(i, j);
            if ((std::abs(b - a)) > 1.0) {  //<< TOLERANCE TO DIFFERENCES!!!!!
                // print the non-matching data only once per-line
                if (static_cast<int32>(i_old) != i) {
                    std::cout << "\n\n\n[HTK-row: " << i << "] "
                              << htk_features.Row(i) << "\n";
                    std::cout << "[Kaldi-row: " << i << "] "
                              << kaldi_features.Row(i) << "\n\n\n";
                    i_old = i;
                }
                // print indices of non-matching cells
                std::cout << "[" << i << ", " << j << "]";
                passed = false;
            }
        }
    }
    if (!passed) KALDI_ERR << "Test failed";

    // write the htk features for later inspection
    HtkHeader header = {
        kaldi_features.NumRows(),
        100000,  // 10ms
        static_cast<int16>(sizeof(float) * kaldi_features.NumCols()),
        021406  // MFCC_D_A_0
    };
    {
        std::ofstream os("tmp.test.wav.fea_kaldi.3",
                         std::ios::out | std::ios::binary);
        WriteHtk(os, kaldi_features, header);
    }

    std::cout << "Test passed :)\n\n";

    unlink("tmp.test.wav.fea_kaldi.3");
}


static void UnitTestHTKCompare4() {
    std::cout << "=== UnitTestHTKCompare4() ===\n";

    std::ifstream is("test_data/test.wav", std::ios_base::binary);
    WaveData wave;
    wave.Read(is);
    KALDI_ASSERT(wave.Data().NumRows() == 1);
    SubVector<BaseFloat> waveform(wave.Data(), 0);

    // read the HTK features
    Matrix<BaseFloat> htk_features;
    {
        std::ifstream is("test_data/test.wav.fea_htk.4",
                         std::ios::in | std::ios_base::binary);
        bool ans = ReadHtk(is, &htk_features, 0);
        KALDI_ASSERT(ans);
    }

    // use mfcc with default configuration...
    MfccOptions op;
    op.frame_opts.dither = 0.0;
    op.frame_opts.window_type = "hamming";
    op.frame_opts.remove_dc_offset = false;
    op.frame_opts.round_to_power_of_two = true;
    op.mel_opts.low_freq = 0.0;
    op.htk_compat = true;
    op.use_energy = true;  // Use energy.
    op.mel_opts.htk_mode = true;

    Mfcc mfcc(op);

    // calculate kaldi features
    Matrix<BaseFloat> kaldi_raw_features;
    mfcc.Compute(waveform, 1.0, &kaldi_raw_features);

    DeltaFeaturesOptions delta_opts;
    Matrix<BaseFloat> kaldi_features;
    ComputeDeltas(delta_opts, kaldi_raw_features, &kaldi_features);

    // compare the results
    bool passed = true;
    int32 i_old = -1;
    KALDI_ASSERT(kaldi_features.NumRows() == htk_features.NumRows());
    KALDI_ASSERT(kaldi_features.NumCols() == htk_features.NumCols());
    // Ignore ends-- we make slightly different choices than
    // HTK about how to treat the deltas at the ends.
    for (int32 i = 10; i + 10 < kaldi_features.NumRows(); i++) {
        for (int32 j = 0; j < kaldi_features.NumCols(); j++) {
            BaseFloat a = kaldi_features(i, j), b = htk_features(i, j);
            if ((std::abs(b - a)) > 1.0) {  //<< TOLERANCE TO DIFFERENCES!!!!!
                // print the non-matching data only once per-line
                if (static_cast<int32>(i_old) != i) {
                    std::cout << "\n\n\n[HTK-row: " << i << "] "
                              << htk_features.Row(i) << "\n";
                    std::cout << "[Kaldi-row: " << i << "] "
                              << kaldi_features.Row(i) << "\n\n\n";
                    i_old = i;
                }
                // print indices of non-matching cells
                std::cout << "[" << i << ", " << j << "]";
                passed = false;
            }
        }
    }
    if (!passed) KALDI_ERR << "Test failed";

    // write the htk features for later inspection
    HtkHeader header = {
        kaldi_features.NumRows(),
        100000,  // 10ms
        static_cast<int16>(sizeof(float) * kaldi_features.NumCols()),
        021406  // MFCC_D_A_0
    };
    {
        std::ofstream os("tmp.test.wav.fea_kaldi.4",
                         std::ios::out | std::ios::binary);
        WriteHtk(os, kaldi_features, header);
    }

    std::cout << "Test passed :)\n\n";

    unlink("tmp.test.wav.fea_kaldi.4");
}


static void UnitTestHTKCompare5() {
    std::cout << "=== UnitTestHTKCompare5() ===\n";

    std::ifstream is("test_data/test.wav", std::ios_base::binary);
    WaveData wave;
    wave.Read(is);
    KALDI_ASSERT(wave.Data().NumRows() == 1);
    SubVector<BaseFloat> waveform(wave.Data(), 0);

    // read the HTK features
    Matrix<BaseFloat> htk_features;
    {
        std::ifstream is("test_data/test.wav.fea_htk.5",
                         std::ios::in | std::ios_base::binary);
        bool ans = ReadHtk(is, &htk_features, 0);
        KALDI_ASSERT(ans);
    }

    // use mfcc with default configuration...
    MfccOptions op;
    op.frame_opts.dither = 0.0;
    op.frame_opts.window_type = "hamming";
    op.frame_opts.remove_dc_offset = false;
    op.frame_opts.round_to_power_of_two = true;
    op.htk_compat = true;
    op.use_energy = true;  // Use energy.
    op.mel_opts.low_freq = 0.0;
    op.mel_opts.vtln_low = 100.0;
    op.mel_opts.vtln_high = 7500.0;
    op.mel_opts.htk_mode = true;

    BaseFloat vtln_warp =
        1.1;  // our approach identical to htk for warp factor >1,
    // differs slightly for higher mel bins if warp_factor <0.9

    Mfcc mfcc(op);

    // calculate kaldi features
    Matrix<BaseFloat> kaldi_raw_features;
    mfcc.Compute(waveform, vtln_warp, &kaldi_raw_features);

    DeltaFeaturesOptions delta_opts;
    Matrix<BaseFloat> kaldi_features;
    ComputeDeltas(delta_opts, kaldi_raw_features, &kaldi_features);

    // compare the results
    bool passed = true;
    int32 i_old = -1;
    KALDI_ASSERT(kaldi_features.NumRows() == htk_features.NumRows());
    KALDI_ASSERT(kaldi_features.NumCols() == htk_features.NumCols());
    // Ignore ends-- we make slightly different choices than
    // HTK about how to treat the deltas at the ends.
    for (int32 i = 10; i + 10 < kaldi_features.NumRows(); i++) {
        for (int32 j = 0; j < kaldi_features.NumCols(); j++) {
            BaseFloat a = kaldi_features(i, j), b = htk_features(i, j);
            if ((std::abs(b - a)) > 1.0) {  //<< TOLERANCE TO DIFFERENCES!!!!!
                // print the non-matching data only once per-line
                if (static_cast<int32>(i_old) != i) {
                    std::cout << "\n\n\n[HTK-row: " << i << "] "
                              << htk_features.Row(i) << "\n";
                    std::cout << "[Kaldi-row: " << i << "] "
                              << kaldi_features.Row(i) << "\n\n\n";
                    i_old = i;
                }
                // print indices of non-matching cells
                std::cout << "[" << i << ", " << j << "]";
                passed = false;
            }
        }
    }
    if (!passed) KALDI_ERR << "Test failed";

    // write the htk features for later inspection
    HtkHeader header = {
        kaldi_features.NumRows(),
        100000,  // 10ms
        static_cast<int16>(sizeof(float) * kaldi_features.NumCols()),
        021406  // MFCC_D_A_0
    };
    {
        std::ofstream os("tmp.test.wav.fea_kaldi.5",
                         std::ios::out | std::ios::binary);
        WriteHtk(os, kaldi_features, header);
    }

    std::cout << "Test passed :)\n\n";

    unlink("tmp.test.wav.fea_kaldi.5");
}

static void UnitTestHTKCompare6() {
    std::cout << "=== UnitTestHTKCompare6() ===\n";


    std::ifstream is("test_data/test.wav", std::ios_base::binary);
    WaveData wave;
    wave.Read(is);
    KALDI_ASSERT(wave.Data().NumRows() == 1);
    SubVector<BaseFloat> waveform(wave.Data(), 0);

    // read the HTK features
    Matrix<BaseFloat> htk_features;
    {
        std::ifstream is("test_data/test.wav.fea_htk.6",
                         std::ios::in | std::ios_base::binary);
        bool ans = ReadHtk(is, &htk_features, 0);
        KALDI_ASSERT(ans);
    }

    // use mfcc with default configuration...
    MfccOptions op;
    op.frame_opts.dither = 0.0;
    op.frame_opts.preemph_coeff = 0.97;
    op.frame_opts.window_type = "hamming";
    op.frame_opts.remove_dc_offset = false;
    op.frame_opts.round_to_power_of_two = true;
    op.mel_opts.num_bins = 24;
    op.mel_opts.low_freq = 125.0;
    op.mel_opts.high_freq = 7800.0;
    op.htk_compat = true;
    op.use_energy = false;  // C0 not energy.

    Mfcc mfcc(op);

    // calculate kaldi features
    Matrix<BaseFloat> kaldi_raw_features;
    mfcc.Compute(waveform, 1.0, &kaldi_raw_features);

    DeltaFeaturesOptions delta_opts;
    Matrix<BaseFloat> kaldi_features;
    ComputeDeltas(delta_opts, kaldi_raw_features, &kaldi_features);

    // compare the results
    bool passed = true;
    int32 i_old = -1;
    KALDI_ASSERT(kaldi_features.NumRows() == htk_features.NumRows());
    KALDI_ASSERT(kaldi_features.NumCols() == htk_features.NumCols());
    // Ignore ends-- we make slightly different choices than
    // HTK about how to treat the deltas at the ends.
    for (int32 i = 10; i + 10 < kaldi_features.NumRows(); i++) {
        for (int32 j = 0; j < kaldi_features.NumCols(); j++) {
            BaseFloat a = kaldi_features(i, j), b = htk_features(i, j);
            if ((std::abs(b - a)) > 1.0) {  //<< TOLERANCE TO DIFFERENCES!!!!!
                // print the non-matching data only once per-line
                if (static_cast<int32>(i_old) != i) {
                    std::cout << "\n\n\n[HTK-row: " << i << "] "
                              << htk_features.Row(i) << "\n";
                    std::cout << "[Kaldi-row: " << i << "] "
                              << kaldi_features.Row(i) << "\n\n\n";
                    i_old = i;
                }
                // print indices of non-matching cells
                std::cout << "[" << i << ", " << j << "]";
                passed = false;
            }
        }
    }
    if (!passed) KALDI_ERR << "Test failed";

    // write the htk features for later inspection
    HtkHeader header = {
        kaldi_features.NumRows(),
        100000,  // 10ms
        static_cast<int16>(sizeof(float) * kaldi_features.NumCols()),
        021406  // MFCC_D_A_0
    };
    {
        std::ofstream os("tmp.test.wav.fea_kaldi.6",
                         std::ios::out | std::ios::binary);
        WriteHtk(os, kaldi_features, header);
    }

    std::cout << "Test passed :)\n\n";

    unlink("tmp.test.wav.fea_kaldi.6");
}

void UnitTestVtln() {
    // Test the function VtlnWarpFreq.
    BaseFloat low_freq = 10, high_freq = 7800, vtln_low_cutoff = 20,
              vtln_high_cutoff = 7400;

    for (size_t i = 0; i < 100; i++) {
        BaseFloat freq = 5000, warp_factor = 0.9 + RandUniform() * 0.2;
        AssertEqual(MelBanks::VtlnWarpFreq(vtln_low_cutoff,
                                           vtln_high_cutoff,
                                           low_freq,
                                           high_freq,
                                           warp_factor,
                                           freq),
                    freq / warp_factor);

        AssertEqual(MelBanks::VtlnWarpFreq(vtln_low_cutoff,
                                           vtln_high_cutoff,
                                           low_freq,
                                           high_freq,
                                           warp_factor,
                                           low_freq),
                    low_freq);
        AssertEqual(MelBanks::VtlnWarpFreq(vtln_low_cutoff,
                                           vtln_high_cutoff,
                                           low_freq,
                                           high_freq,
                                           warp_factor,
                                           high_freq),
                    high_freq);
        BaseFloat freq2 = low_freq + (high_freq - low_freq) * RandUniform(),
                  freq3 = freq2 +
                          (high_freq - freq2) * RandUniform();  // freq3>=freq2
        BaseFloat w2 = MelBanks::VtlnWarpFreq(vtln_low_cutoff,
                                              vtln_high_cutoff,
                                              low_freq,
                                              high_freq,
                                              warp_factor,
                                              freq2);
        BaseFloat w3 = MelBanks::VtlnWarpFreq(vtln_low_cutoff,
                                              vtln_high_cutoff,
                                              low_freq,
                                              high_freq,
                                              warp_factor,
                                              freq3);
        KALDI_ASSERT(w3 >= w2);  // increasing function.
        BaseFloat w3dash = MelBanks::VtlnWarpFreq(
            vtln_low_cutoff, vtln_high_cutoff, low_freq, high_freq, 1.0, freq3);
        AssertEqual(w3dash, freq3);
    }
}

static void UnitTestFeat() {
    UnitTestVtln();
    UnitTestReadWave();
    UnitTestSimple();
    UnitTestHTKCompare1();
    UnitTestHTKCompare2();
    // commenting out this one as it doesn't compare right now I normalized
    // the way the FFT bins are treated (removed offset of 0.5)... this seems
    // to relate to the way frequency zero behaves.
    UnitTestHTKCompare3();
    UnitTestHTKCompare4();
    UnitTestHTKCompare5();
    UnitTestHTKCompare6();
    std::cout << "Tests succeeded.\n";
}


int main() {
    try {
        for (int i = 0; i < 5; i++) UnitTestFeat();
        std::cout << "Tests succeeded.\n";
        return 0;
    } catch (const std::exception &e) {
        std::cerr << e.what();
        return 1;
    }
}