Surrey CVSSP DCASE 2018 Task 2 System

This is the source code for CVSSP's system used in DCASE 2018 Task 2.

For more details about the system, consider reading the technical report or the workshop paper¹.

Requirements

This software requires Python 3. To install the dependencies, run:

pipenv install

or:

pip install -r requirements.txt

The main functionality of this software also requires the DCASE 2018 Task 2 datasets, which may be downloaded here. After acquiring the datasets, modify task2/config/dcase2018_task2.py accordingly.

For example:

_root_dataset_path = ('/path/to/datasets')
"""str: Path to root directory containing input audio clips."""

training_set = Dataset(
    name='training',
    path=os.path.join(_root_dataset_path, 'audio_train'),
    metadata_path='metadata/training.csv',
)
"""Dataset instance for the training dataset."""

You will also want to change the work path in task2/config/paths.py:

work_path = '/path/to/workspace'
"""str: Path to parent directory containing program output."""

Usage

In this section, the various commands are described. Using this software, the user is able to apply preprocessing (silence removal), extract feature vectors, train the network, generate predictions, and evaluate the predictions.

Preprocessing

Our implementation of preprocessing involves extracting the non-silent sections of audio clips and saving these to disk separately. A new metadata file is then created with entries corresponding to the new files.

To apply preprocessing, run:

python task2/main.py preprocess <training/test>

Refer to task2/silence.py for the relevant code.

Feature Extraction

To extract feature vectors, run:

python task2/main.py extract <training/test> [--recompute]

If --recompute is enabled, the program will recompute existing feature vectors. This implementaion extracts log-mel spectrogram features. See task2/config/logmel.py for tweaking the parameters.

Training

To train a model, run:

python task2/main.py train [--model MODEL] [--fold n] [--sample_weight x] [--class_weight]

The --model option can be one of the following:

• vgg13
• gcnn
• crnn
• gcrnn

The training set is assumed to be split into several folds, so the --fold option specifies which one to use as the validation set. If set to -1, the program trains on the entire dataset. The --sample_weight option allows setting a sample weight to be used for unverified (noisy) examples. Finally, setting the --class_weight flag indicates that examples should be weighted based on the class that they belong to.

See task2/config/training.py for tweaking the parameters or task2/training.py for further modifications.

Prediction

To generate predictions, run:

python task2/main.py predict <training/test> [--fold n]

The --fold option specifies which fold-specific model to use.

See task2/config/predictions.py to modify which epochs are selected for generating the predictions. By default, the top four models based on their MAP score on the validation set are chosen.

Evaluation

To evaluate the predictions, run:

python task2/main.py evaluate <training/test> [--fold n]

Stacking

Stacking is an ensembling technique that involves creating meta-features based on the predictions of a number of base classifiers. These meta-features are then used to train a second-level classifier and generate new predictions. We provide scripts to do this.

To generate meta-features, run:

python scripts/meta_features.py <pred_path> <pred_type> <output_path>

The argument pred_path refers to the parent directory in which the predictions of the base classifiers are stored. pred_type must be either training or test, depending on which dataset the meta-features are for. output_path specifies the path of the output HDF5 file.

To give an example, assume that the directory structure looks like this:

workspace
├── predictions
│   ├── classifier1
│   ├── classifier2
│   ├── classifier3

In this case, you might run:

python scripts/meta_features.py workspace/predictions training training.h5
python scripts/meta_features.py workspace/predictions test test.h5

For the time being, the script must be edited to select the classifiers.

To then generate predictions using a second-level classifier, run:

python scripts/predict_stack.py --test_path test.h5 training.h5 <metadata_path> <output_path>

The argument metadata_path is the path to the training set metadata file. See the script itself for more details.

Pseudo-labeling

To relabel or promote training examples, run:

python scripts/relabel.py <metadata_path> <pred_path> <output_path> [--relabel_threshold t1] [--promote_threshold t2]

The argument metadata_path is the path to the training set metadata file containing the original labels. pred_path is the path to the predictions file used for pseudo-labeling. output_path is the path of the new metadata file to be written. The threshold options allow constraining which examples are relabeled or promoted.

Citing

If you wish to cite this work, please cite the following paper:

---

1. T. Iqbal, Q. Kong, M. D. Plumbley, and W. Wang, "General-Purpose Audio Tagging from Noisy Labels using Convolutional Neural Networks," in Detection and Classification of Acoustic Scenes and Events 2018 Workshop, Woking, UK, 2018, pp. 212–216.↩