Pitch and MFCC output lengths differ for same input audio

[scottbreyfogle]

For certain input audio lengths, pitch calculation and MFCC calculation will produce different length results. See below for a minimal repro. Here is the output of this script: output.txt

#include "feat/feature-mfcc.h"
#include "feat/pitch-functions.h"
#include "feat/wave-reader.h"

int main() {
  using namespace kaldi;
  PitchExtractionOptions pitch_options;
  ProcessPitchOptions opp;
  WaveData wave;
  MfccOptions mfcc_options;
  Mfcc mfcc(mfcc_options);

  for (int i = 400; i < 4000; i++) {
    Vector<BaseFloat> waveform(i);
    Matrix<BaseFloat> m1, m2;
    ComputeAndProcessKaldiPitch(pitch_options, opp, waveform, &m1);
    mfcc.Compute(waveform, 1.0, &m2);
    if (m1.NumRows() != m2.NumRows()) {
      KALDI_LOG << "I: " << i << " Pitch " << m1.NumRows() << " MFCC " << m2.NumRows();
    }
  }
}

Note that the phenomenon happens when approaching 600, 720, 880. I think the pattern is when
len(input) - frame_size) % frame_shift > 156
i.e. len(input) - 400) % 160 > 156
i.e. in the last 3 samples oof each frame calculation window (?)
Assuming these values are right, I think that the MFCC lengths are as expected, and pitch extraction sometimes returns one more frame than expected

Doesn't seem like a major bug, but caused some headaches for me when using the MFA library (ref)