PESTO: Pitch Estimation with Self-supervised Transposition-equivariant Objective

tl;dr: Fast and powerful pitch estimator based on machine learning

This code is the implementation of the PESTO paper, that has been accepted at ISMIR 2023.

Disclaimer: This repository contains minimal code and should be used for inference only. If you want full implementation details or want to use PESTO for research purposes, take a look at this repository (coming soon!).

Installation

pip install pesto-pitch

That's it!

Dependencies

This repository is implemented in PyTorch and has the following additional dependencies:

• numpy for basic I/O operations
• torchaudio for audio loading
• matplotlib for exporting pitch predictions as images (optional)

Usage

Command-line interface

This package includes a CLI as well as pretrained models. To use it, type in a terminal:

pesto my_file.wav

or

python -m pesto my_file.wav

Output formats

The output format can be specified with option -e/--export_format. By default, the predicted pitch is saved in a .csv file that looks like this:

time,frequency,confidence
0.00,185.616,0.907112
0.01,186.764,0.844488
0.02,188.356,0.798015
0.03,190.610,0.746729
0.04,192.952,0.771268
0.05,195.191,0.859440
0.06,196.541,0.864447
0.07,197.809,0.827441
0.08,199.678,0.775208
...

This structure is voluntarily the same as in CREPE repo for easy comparison between both methods.

Alternatively, one can save timesteps, pitch, confidence and activation outputs as a .npz file.

Finally, you can also visualize the pitch predictions by exporting them as a png file (you need matplotlib to be installed for PNG export). Here is an example:

Multiple formats can be specified after the -e option.

Batch processing

Any number of audio files can be passed in the command for convenient batch processing. For example, to estimate the pitch of a whole folder of MP3 files, just type:

pesto my_folder/*.mp3

Audio format

Internally, this repository uses torchaudio for loading audio files. Most audio formats should be supported; refer to torchaudio's documentation for more information. Additionally, audio files can have any sampling rate; no resampling is required.

Pitch prediction from the output probability distribution

By default, the model returns a probability distribution over all pitch bins. To convert it to a proper pitch, by default, we use Argmax-Local Weighted Averaging as in CREPE:

Alternatively, one can use basic argmax of weighted average with option -r/--reduction.

Miscellaneous

• The step size of the pitch predictions can be specified (in milliseconds) with option -s. Note that this number is then converted to an integer hop length for the CQT so there might be a slight difference between the step size you specify and the actual one.
• You can use -F option to return directly pitch predictions in semitones instead of frequency.
• If you can access a GPU, inference speed can be further improved with option --gpu <gpu_id>. --gpu -1 (the default) corresponds to CPU.

Python API

Alternatively, the functions defined in pesto/predict.py can directly be called within another Python code. In particular, the function predict_from_files is the one that the CLI directly calls.

Basic usage

import torchaudio
import pesto

# predict the pitch of your audio tensors directly within your own Python code
x, sr = torchaudio.load("my_file.wav")
timesteps, pitch, confidence, activations = pesto.predict(x, sr, step_size=10.)

# You can also predict pitches from audio files directly
pesto.predict_from_files(["example1.wav", "example2.mp3", "example3.ogg"], step_size=10., export_format=["csv"])

Advanced usage

If not provided, pesto.predict will first load the CQT kernels and the model before performing any pitch estimation. If you want to process a significant number of files, calling predict several times will then re-initialize the same model for each tensor.

To avoid this time-consuming step, one can manually instantiate the model and data processor, then pass them directly as args to the predict function. To do so, one has to use the underlying methods from pesto.utils:

import torch

from pesto import predict
from pesto.utils import load_model, load_dataprocessor

device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")
model = load_model("mir-1k", device=device)
data_processor = load_dataprocessor(step_size=0.01, device=device)

for x, sr in ...:
    data_processor.sampling_rate = sr  # The data_processor handles waveform->CQT conversion so it must know the sampling rate
    predictions = predict(x, sr, model=model)
    ...

Note that when passing a list of files to pesto.predict_from_files(...) or the CLI directly, the model is loaded only once so you don't have to bother with that in general.

Batched pitch estimation

By default, the function pesto.predict takes an audio waveform represented as a Tensor object of shape (num_channels, num_samples). However, one may want to estimate the pitch of batches of (cropped) waveforms within a training pipeline, e.g. for DDSP-related applications. pesto.predict therefore accepts Tensor inputs of shape (batch_size, num_channels, num_samples) and returns batch-wise pitch predictions accordingly.

Note that batched predictions are available only from the Python API and not from the CLI because:

• handling audios of different lengths is annoying, I don't want to bother with that
• when estimating pitch on

Performances

On MIR-1K and MDB-stem-synth, PESTO outperforms other self-supervised baselines. Its performances are close to CREPE's, which has 800x more parameters and was trained in a supervised way on a vast dataset containing MIR-1K and MDB-stem-synth, among others.

Speed benchmark

PESTO is a very lightweight model and is therefore very fast at inference time. As CQT frames are processed independently, the actual speed of the pitch estimation process mainly depends on the granularity of the predictions, which can be controlled with the --step_size parameter (10ms by default).

Here is a speed comparison between CREPE and PESTO, averaged over 10 runs on the same machine.

• Audio file: wav format, 2m51s
• Hardware: 11th Gen Intel(R) Core(TM) i7-1185G7 @ 3.00GHz, 8 cores

Note that the y-axis is in log-scale: with a step size of 10ms (the default), PESTO would perform pitch estimation of the file in 13 seconds (~12 times faster than real-time) while CREPE would take 12 minutes! It is therefore more suited to applications that need very fast pitch estimation without relying on GPU resources.

Inference on GPU

The underlying PESTO pitch estimator is a standard PyTorch module and can therefore use the GPU, if available, by setting option --gpu to the id of the device you want to use for pitch estimation.

Under the hood, the input is passed to the model as a single batch of CQT frames, so pitch is estimated for the whole track in parallel, making inference extremely fast.

However, when dealing with very large audio files, processing the whole track at once can lead to OOM errors. To circumvent this, one can split the batch of CQT frames into multiple chunks by setting option -c/--num_chunks. Chunks will be processed sequentially, thus reducing memory usage.

As an example, a 48kHz audio file of 1 hour can be processed in 20 seconds only on a single GTX 1080 Ti when split into 10 chunks.

Contributing

• Currently, only a single model trained on MIR-1K is provided. Feel free to play with the architecture, training data or hyperparameters and to submit your checkpoints as PRs if you get better performances than the provided pretrained model.
• Despite PESTO being significantly faster than real-time, it is currently implemented as standard PyTorch and may be further accelerated. Any suggestions for improving speed are more than welcome!

More generally, do not hesitate to contact me if you have ideas to improve PESTO's recipe!

Cite

If you want to use this work, please cite:

@inproceedings{PESTO,
    author = {Riou, Alain and Lattner, Stefan and Hadjeres, Gaëtan and Peeters, Geoffroy},
    booktitle = {Proceedings of the 24th International Society for Music Information Retrieval Conference, ISMIR 2023},
    publisher = {International Society for Music Information Retrieval},
    title = {PESTO: Pitch Estimation with Self-supervised Transposition-equivariant Objective},
    year = {2023}
}

Credits

• nnAudio for the original CQT implementation
• multipitch-architectures for the original architecture of the model

@ARTICLE{9174990,
    author={K. W. {Cheuk} and H. {Anderson} and K. {Agres} and D. {Herremans}},
    journal={IEEE Access}, 
    title={nnAudio: An on-the-Fly GPU Audio to Spectrogram Conversion Toolbox Using 1D Convolutional Neural Networks}, 
    year={2020},
    volume={8},
    number={},
    pages={161981-162003},
    doi={10.1109/ACCESS.2020.3019084}}
@ARTICLE{9865174,
    author={Weiß, Christof and Peeters, Geoffroy},
    journal={IEEE/ACM Transactions on Audio, Speech, and Language Processing}, 
    title={Comparing Deep Models and Evaluation Strategies for Multi-Pitch Estimation in Music Recordings}, 
    year={2022},
    volume={30},
    number={},
    pages={2814-2827},
    doi={10.1109/TASLP.2022.3200547}}