Begin to add compute-kaldi-pitch-feats

kaldifeat/csrc/pitch-functions.h

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+// kaldifeat/csrc/pitch-functions.h
+//
+// Copyright (c)  2021  Xiaomi Corporation (authors: Fangjun Kuang)
+
+// This file is copied/modified from kaldi/src/feat/pitch-functions.h
+
+#ifndef KALDIFEAT_CSRC_FEATURE_PITCH_FUNCTIONS_H_
+#define KALDIFEAT_CSRC_FEATURE_PITCH_FUNCTIONS_H_
+
+#include "torch/torch.h"
+
+namespace kaldifeat {
+
+struct PitchExtractionOptions {
+  // sample frequency in hertz
+  // must match the waveform file
+  float samp_freq = 16000;
+  float frame_shift_ms = 10.0;   // in milliseconds.
+  float frame_length_ms = 25.0;  // in milliseconds.
+
+  // Preemphasis coefficient. [use is deprecated.]
+  float preemph_coeff = 0.0;
+
+  float min_f0 = 50;            // min f0 to search (Hz)
+  float max_f0 = 400;           // max f0 to search (Hz)
+  float soft_min_f0 = 10.0;     // Minimum f0, applied in soft way, must not
+                                // exceed min-f0
+  float penalty_factor = 0.1;   // cost factor for FO change
+  float lowpass_cutoff = 1000;  // cutoff frequency for Low pass filter (Hz)
+
+  // Integer that determines filter width when
+  // upsampling NCCF
+  // Frequency that we down-sample the signal to.  Must be
+  // more than twice lowpass-cutoff
+  float resample_freq = 4000;
+
+  float delta_pitch = 0.005;          // the pitch tolerance in pruning lags
+  float nccf_ballast = 7000;          // Increasing this factor reduces NCCF for
+                                      // quiet frames, helping ensure pitch
+                                      // continuity in unvoiced region
+  int32_t lowpass_filter_width = 1;   // Integer that determines filter width of
+                                      // lowpass filter
+  int32_t upsample_filter_width = 5;  // Integer that determines filter width
+                                      // when upsampling NCCF
+
+  // Below are newer config variables, not present in the original paper,
+  // that relate to the online pitch extraction algorithm.
+
+  // The maximum number of frames of latency that we allow the pitch-processing
+  // to introduce, for online operation. If you set this to a large value,
+  // there would be no inaccuracy from the Viterbi traceback (but it might make
+  // you wait to see the pitch). This is not very relevant for the online
+  // operation: normalization-right-context is more relevant, you
+  // can just leave this value at zero.
+  int32_t max_frames_latency = 0;
+
+  // Only relevant for the function ComputeKaldiPitch which is called by
+  // compute-kaldi-pitch-feats. If nonzero, we provide the input as chunks of
+  // this size. This affects the energy normalization which has a small effect
+  // on the resulting features, especially at the beginning of a file. For best
+  // compatibility with online operation (e.g. if you plan to train models for
+  // the online-deocding setup), you might want to set this to a small value,
+  // like one frame.
+  int32_t frames_per_chunk = 0;
+
+  // Only relevant for the function ComputeKaldiPitch which is called by
+  // compute-kaldi-pitch-feats, and only relevant if frames_per_chunk is
+  // nonzero. If true, it will query the features as soon as they are
+  // available, which simulates the first-pass features you would get in online
+  // decoding. If false, the features you will get will be the same as those
+  // available at the end of the utterance, after InputFinished() has been
+  // called: e.g. during lattice rescoring.
+  bool simulate_first_pass_online = false;
+
+  // Only relevant for online operation or when emulating online operation
+  // (e.g. when setting frames_per_chunk). This is the frame-index on which we
+  // recompute the NCCF (e.g. frame-index 500 = after 5 seconds); if the
+  // segment ends before this we do it when the segment ends. We do this by
+  // re-computing the signal average energy, which affects the NCCF via the
+  // "ballast term", scaling the resampled NCCF by a factor derived from the
+  // average change in the "ballast term", and re-doing the backtrace
+  // computation. Making this infinity would be the most exact, but would
+  // introduce unwanted latency at the end of long utterances, for little
+  // benefit.
+  int32_t recompute_frame = 500;
+
+  // This is a "hidden config" used only for testing the online pitch
+  // extraction. If true, we compute the signal root-mean-squared for the
+  // ballast term, only up to the current frame, rather than the end of the
+  // current chunk of signal. This makes the output insensitive to the
+  // chunking, which is useful for testing purposes.
+  bool nccf_ballast_online = false;
+  bool snip_edges = true;
+
+  torch::Device device{"cpu"};
+
+  PitchExtractionOptions() = default;
+
+  /// Returns the window-size in samples, after resampling.  This is the
+  /// "basic window size", not the full window size after extending by max-lag.
+  // Because of floating point representation, it is more reliable to divide
+  // by 1000 instead of multiplying by 0.001, but it is a bit slower.
+  int32_t NccfWindowSize() const {
+    return static_cast<int32_t>(resample_freq * frame_length_ms / 1000.0);
+  }
+  /// Returns the window-shift in samples, after resampling.
+  int32_t NccfWindowShift() const {
+    return static_cast<int32_t>(resample_freq * frame_shift_ms / 1000.0);
+  }
+
+  std::string ToString() const {
+    std::ostringstream os;
+    os << "samp_freq: " << samp_freq << "\n";
+    os << "frame_shift_ms: " << frame_shift_ms << "\n";
+    os << "frame_length_ms: " << frame_length_ms << "\n";
+    os << "preemph_coeff: " << preemph_coeff << "\n";
+    os << "min_f0: " << min_f0 << "\n";
+    os << "max_f0: " << max_f0 << "\n";
+    os << "soft_min_f0: " << soft_min_f0 << "\n";
+    os << "penalty_factor: " << penalty_factor << "\n";
+    os << "lowpass_cutoff: " << lowpass_cutoff << "\n";
+    os << "resample_freq: " << resample_freq << "\n";
+    os << "delta_pitch: " << delta_pitch << "\n";
+    os << "nccf_ballast: " << nccf_ballast << "\n";
+    os << "lowpass_filter_width: " << lowpass_filter_width << "\n";
+    os << "upsample_filter_width: " << upsample_filter_width << "\n";
+    os << "max_frames_latency: " << max_frames_latency << "\n";
+    os << "frames_per_chunk: " << frames_per_chunk << "\n";
+    os << "simulate_first_pass_online: " << simulate_first_pass_online << "\n";
+    os << "recompute_frame: " << recompute_frame << "\n";
+    os << "nccf_ballast_online: " << nccf_ballast_online << "\n";
+    os << "snip_edges: " << snip_edges << "\n";
+    os << "device: " << device << "\n";
+  }
+};
+
+}  // namespace kaldifeat
+
+#endif  // KALDIFEAT_CSRC_FEATURE_PITCH_FUNCTIONS_H_