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Sound Event Bounding Boxes (SEBBs)

A package for the prediction of sound event bounding boxes (SEBBs) as introduced in

Sound Event Bounding Boxes J. Ebbers, F. Germain, G. Wichern and J. Le Roux, Accepted for publication at Interspeech 2024 https://arxiv.org/abs/2406.04212

SEBBs are one-dimensional bounding boxes defined by event onset time, event offset time, sound class and a confidence. They represent sound event candidates with a scalar confidence score assigned to it. We call it (1d) bounding boxes to highlight the similarity to the (2d) bounding boxes typically used for object detection in computer vision.

The final sound event detection can then be derived by a (class-wise) event-level thresholding of the SEBBs' confidences. Here, all SEBBs/candidates, whose confidence exceed the threshold, are accepted as a detection, while discarding the rest. The threshold can be used to control a system's sensitivity.

E.g., when a high sensitivity/recall (few missed hits) is required, a low detection threshold can be used to detect events even when the system's confidence is low. When a high precision (few false alarms) is desired instead, a higher threshold may be used to only detect events with high confidence.

With SEBBs the sensitivity of a system can be controlled without an impact on the detection of an events' on- and offset times, which the previous frame-level thresholding approach was suffering from.

Table of contents

Installation

Install package directly

$ pip install git+https://github.com/merlresearch/sebbs.git

or clone and install (editable)

$ git clone https://github.com/merlresearch/sebbs.git
$ cd sebbs
$ pip install --editable .

Usage

Currently, the package supports change-detection-based SEBBs (cSEBBs), which are inferred by a post-processing of frame-level posterior scores.

Hyper-parameter tuning

To perform hyper-parameter tuning of step_filter_length, merge_threshold_abs and merge_threshold_rel simply call sebbs.csebbs.tune, which runs tuning and returns a sebbs.csebbs.CSEBBsPredictor instance. To tune hyper-parameters w.r.t. PSDS1 run

from sebbs import csebbs

csebbs_predictor_psds, best_psds_values = csebbs.tune(
    scores="/path/to/validation/scores",
    ground_truth="/path/to/validation/ground_truth.tsv",
    audio_durations="/path/to/validation/audio_durations.tsv",
    step_filter_lengths=(.32, .48, .64),
    merge_thresholds_abs=(.15, .2, .3),
    merge_thresholds_rel=(1.5, 2., 3.),
    selection_fn=csebbs.select_best_psds,
    dtc_threshold=.7, gtc_threshold=.7,
    cttc_threshold=None, alpha_ct=0.,
)

Scores, ground_truth and audio_durations must be of the same format as used by sed_scores_eval and can be either paths or dictionaries with the (loaded) data. An example of the required file format can be found in tests/dcase2023task4a. To alternatively tune hyper-parameters w.r.t. collar-based F1-score run

csebbs_predictor_cbf, best_cbf_values = csebbs.tune(
    scores="/path/to/validation/scores",
    ground_truth="/path/to/validation/ground_truth.tsv",
    audio_durations="/path/to/validation/audio_durations.tsv",
    step_filter_lengths=(.32, .48, .64),
    merge_thresholds_abs=(.15, .2, .3),
    merge_thresholds_rel=(1.5, 2., 3.),
    selection_fn=csebbs.select_best_cbf,
    onset_collar=.2, offset_collar=.2, offset_collar_rate=.2,
)

To tune hyper-parameters for both PSDS and collar-based F1-score in the same grid-search run

csebbs_predictors = csebbs.tune(
    scores="/path/to/validation/scores",
    ground_truth="/path/to/validation/ground_truth.tsv",
    audio_durations="/path/to/validation/audio_durations.tsv",
    step_filter_lengths=(.32, .48, .64),
    merge_thresholds_abs=(.15, .2, .3),
    merge_thresholds_rel=(1.5, 2., 3.),
    selection_fn=csebbs.select_best_psds_and_cbf,
    dtc_threshold=.7, gtc_threshold=.7,
    cttc_threshold=None, alpha_ct=0.,
    onset_collar=.2, offset_collar=.2, offset_collar_rate=.2,
)
csebbs_predictor_psds, best_psds_values = csebbs_predictors['psds']
csebbs_predictor_cbf, best_cbf_values = csebbs_predictors['cbf']

You can also implement a custom selection_fn to define the criterion for hyper-parameter selection yourself.

We also provide median filter baseline code following the same API, which can, e.g., be tuned as:

import numpy as np
from sebbs import median_filter

median_filter_psds, best_psds_values = median_filter.tune(
    scores="/path/to/validation/scores",
    ground_truth="/path/to/validation/ground_truth.tsv",
    audio_durations="/path/to/validation/audio_durations.tsv",
    filter_lengths=np.linspace(0.,2.,11),
    selection_fn=median_filter.select_best_psds,
    dtc_threshold=.7, gtc_threshold=.7,
    cttc_threshold=None, alpha_ct=0.,
)

Inference

To run inference with a given instance csebbs_predictor call:

csebbs_predictions = csebbs_predictor.predict("/path/to/test/scores")

To make the method directly return sebbs as sed scores data frames for direct use with sed_scores_eval call

csebbs_sed_scores = csebbs_predictor.predict("/path/to/test/scores", return_sed_scores=True)

Then, test performance in terms of, e.g., PSDS1 can be obtained as:

psds, single_class_psds, *_ = sed_scores_eval.intersection_based.psds(
    scores=csebbs_sed_scores,
    ground_truth="/path/to/test/ground_truth.tsv",
    audio_durations="/path/to/test/audio_durations.tsv",
    dtc_threshold=.7, gtc_threshold=.7,
    alpha_ct=.0, alpha_st=1., unit_of_time='hour', max_efpr=100.,
)

Paper results reproduction

To reproduce a system's cross-validation performance from our paper run:

import numpy as np
from sebbs import csebbs, median_filter, package_dir
from sed_scores_eval import io, intersection_based, collar_based

# load predictions, ground_truth, and audio_durations
scores = io.read_sed_scores("/path/to/dcase2023task4a/system/scores")
ground_truth = io.read_ground_truth_events(
    f"{package_dir}/tests/dcase2023task4a/metadata/ground_truth.tsv")
scores = {audio_id: scores[audio_id] for audio_id in ground_truth}
audio_durations = io.read_audio_durations(
    f"{package_dir}/tests/dcase2023task4a/metadata/audio_durations.tsv")
audio_durations = {audio_id: audio_durations[audio_id] for audio_id in ground_truth}

# 5-fold cross validation split
n_folds = 5
all_keys = scores.keys()
shuffled_keys = sorted(all_keys)
np.random.RandomState(0).shuffle(shuffled_keys)
split_idx = np.linspace(0, len(shuffled_keys), n_folds + 1).astype(int).tolist()
folds = [set(shuffled_keys[split_idx[i]:split_idx[i + 1]]) for i in range(n_folds)]

# median_filter cross validation
median_filters, mf_scores, mf_detections = median_filter.cross_validation(
    scores=scores, ground_truth=ground_truth,
    audio_durations=audio_durations, folds=folds,
    filter_lengths=np.linspace(0., 2., 11),
    selection_fn=median_filter.select_best_psds_and_cbf,
    return_sed_scores=True,
)
# evaluate PSDS performance
psds_mf, single_class_psds_mf, *_ = intersection_based.psds(
    scores=mf_scores['psds'], ground_truth=ground_truth,
    audio_durations=audio_durations,
    dtc_threshold=.7, gtc_threshold=.7,
    alpha_ct=.0, alpha_st=1., unit_of_time='hour', max_efpr=100.,
)
# evaluate collar-based F1-score performance
f_mf, *_ = collar_based.fscore(
    scores=mf_detections['cbf'], ground_truth=ground_truth,
    threshold=.5,  # can be any number between 0 and 1 here as the sed_scores obtained from detection are binary
    onset_collar=.2, offset_collar=.2, offset_collar_rate=.2,
)

# csebbs cross validation
csebbs_predictors, csebbs_scores, csebbs_detections = csebbs.cross_validation(
    scores=scores, ground_truth=ground_truth,
    audio_durations=audio_durations, folds=folds,
    step_filter_lengths=(.32, .48, .64),
    merge_thresholds_abs=(.15, .2, .3),
    merge_thresholds_rel=(1.5, 2., 3.),
    selection_fn=csebbs.select_best_psds_and_cbf,
    return_sed_scores=True,
)
# evaluate PSDS performance
psds_csebbs, single_class_psds_csebbs, *_ = intersection_based.psds(
    scores=csebbs_scores['psds'], ground_truth=ground_truth, audio_durations=audio_durations,
    dtc_threshold=.7, gtc_threshold=.7,
    alpha_ct=.0, alpha_st=1., unit_of_time='hour', max_efpr=100.,
)
# evaluate collar-based F1-score performance
f_csebbs, *_ = collar_based.fscore(
    scores=csebbs_detections['cbf'], ground_truth=ground_truth,
    threshold=.5,  # can be any number between 0 and 1 here as the sed_scores obtained from detection are binary
    onset_collar=.2, offset_collar=.2, offset_collar_rate=.2,
)

DCASE 2024 Task 4

To facilitate the usage of cSEBBs for DCASE 2024 Task 4, we provide an example script dcase2024.py showing how to tune hyper parameters and infer output scores for DCASE 2024 Task 4 Baseline.

Contributing

See CONTRIBUTING.md for our policy on contributions.

Copyright and license

Released under AGPL-3.0-or-later license, as found in the LICENSE.md file.

All files, except as listed below:

Copyright (c) 2024 Mitsubishi Electric Research Laboratories (MERL)

SPDX-License-Identifier: AGPL-3.0-or-later

Files in tests/dcase2023task4a/baseline2_run1_scores were copied from Submissions DCASE 2023 Task4a:

Copyright (C) 2023, Janek Ebbers, Romain Serizel, Francesca Ronchini, Florian Angulo, David Perera, Slim Essid

SPDX-License-Identifier: CC-BY-4.0

Files in tests/dcase2023task4a/metadata were adapted from Evaluation set DCASE 2021 task 4:

Copyright (C) 2021, Francesca Ronchini, Nicolas Turpault, Romain Serizel, Scott Wisdom, Hakan Erdogan, John Hershey, Justin Salamon, Prem Seetharaman, Eduardo Fonseca, Samuele Cornell, Daniel P. W. Ellis

SPDX-License-Identifier: CC-BY-4.0

Content of scripts/utils.py was copied from DCASE 2024 Task 4 Baseline:

Copyright (C) 2024, Romain Serizel

SPDX-License-Identifier: MIT