torchcrepe 0.0.2

Pytorch implementation of CREPE pitch tracker

torchcrepe

Pytorch implementation of the CREPE pitch tracker. The original Tensorflow implementation can be found here. The provided model weights were obtained by converting the "tiny" and "full" models using MMdnn, an open-source model management framework.

Installation

Perform the system-dependent PyTorch install using the instructions found here.

pip install torchcrepe

Usage

Computing pitch and harmonicity from audio

import torchcrepe


# Load audio
audio, sr = torchcrepe.load.audio( ... )

# Place the audio on the device you want CREPE to run on
audio = audio.to( ... )

# Here we'll use a 5 millisecond hop length
hop_length = int(sr / 200.)

# Provide a sensible frequency range for your domain (upper limit is 2006 Hz)
# This would be a reasonable range for speech
fmin = 50
fmax = 550

# Select a model capacity--one of "tiny" or "full"
model = 'tiny'

# Compute pitch and harmonicity
pitch = torchcrepe.predict(audio, sr, hop_length, fmin, fmax, model)

A harmonicity metric similar to the Crepe confidence score can also be extracted by passing return_harmonicity=True to torchcrepe.predict.

By default, torchcrepe uses Viterbi decoding on the softmax of the network output. This is different than the original implementation, which uses a weighted average near the argmax of binary cross-entropy probabilities. The argmax operation can cause double/half frequency errors. These can be removed by penalizing large pitch jumps via Viterbi decoding. The decode submodule provides some options for decoding.

# Decode using viterbi decoding (default)
torchcrepe.predict(..., decoder=torchcrepe.decode.viterbi)

# Decode using weighted argmax (as in the original implementation)
torchcrepe.predict(..., decoder=torchcrepe.decode.weighted_argmax)

# Decode using argmax
torchcrepe.predict(..., decoder=torchcrepe.decode.argmax)

When harmonicity is low, the pitch is less reliable. For some problems, it makes sense to mask these less reliable pitch values. However, the harmonicity can be noisy and the pitch has quantization artifacts. torchcrepe provides submodules filter and threshold for this purpose. The filter and threshold parameters should be tuned to your data. For clean speech, a 10-20 millisecond window with a threshold of 0.21 has worked.

# We'll use a 15 millisecond window assuming a hop length of 5 milliseconds
win_length = 3

# Median filter noisy confidence value
harmonicity = torchcrepe.filter.median(harmonicity, win_length)

# Remove inharmonic regions
pitch = torchcrepe.threshold.At(.21)(pitch, harmonicity)

# Optionally smooth pitch to remove quantization artifacts
pitch = torchcrepe.filter.mean(pitch, win_length)

For more fine-grained control over pitch thresholding, see torchcrepe.threshold.Hysteresis. This is especially useful for removing spurious voiced regions caused by noise in the harmonicity values, but has more parameters and may require more manual tuning to your data.

Computing the CREPE model output activations

probabilities = torchcrepe.infer(torchcrepe.preprocess(audio, sr, hop_length))

Computing the CREPE embedding space

As in Differentiable Digital Signal Processing, this uses the output of the fifth max-pooling layer as a pretrained pitch embedding

embeddings = torchcrepe.embed(audio, sr, hop_length)

Computing from files

torchcrepe defines the following functions convenient for predicting directly from audio files on disk. Each of these functions also takes a device argument that can be used for device placement (e.g., device='gpu:0').

torchcrepe.predict_from_file(audio_file, ...)
torchcrepe.predict_from_file_to_file(
    audio_file, ..., output_pitch_file, output_harmonicity_file)

torchcrepe.embed_from_file(audio_file, ...)
torchcrepe.embed_from_file_to_file(audio_file, ..., output_file)

Command-line interface

Tests

The module tests can be run as follows.

pip install pytest
pytest