feature_extraction

Feature extraction codes (in MATLAB)

extract_features.m - Extracts frame-level features from a specified audio and saves them in a structure as a .mat file. To extract features for an audio file, simply run

extract_features('path/to/file/filename.wav')

Features get saved in a folder called features_from_matlab in a features folder (created by the script) above the codes directory. The saved structure variable contains the following fields:

• tempo_sal - Tempo and salience
• rhythm_features - Posteriors of tempo and salience
• ste_sc_diff - Biphasic filtered short-time energy and short-time spectral centroid
• avg_MFCC - Mel-Frequency Cepstral Coefficients

All features are calculated at a short-time frame level and then averaged using longer overlapping windows of size 3s with a hop of 1s. These are the default values as reported in the paper, but can be modified using commandline arguments (see below). Every feature is stored as a column vector with each column corresponding to a 1s frame. The ste_sc_diff and avg_MFCC together constitute the timbre features. Refer to Figure 9 of the paper for a detailed block diagram of the feature extraction process.

Additional details

Full syntax - extract_features(in_path,Name,Value)
in_path is either the name of an audio file or a text file containing a column-list of audio filenames. It is a mandatory argument. It can also be a csv file in a format similar to the annotation files.
Additional optional arguments can be specified using Name, Value pairs, and include the following:

• in_dir - path to the audio file(s) if in_path is only the name of the audio file without the full path; useful if in_path is a text file with only the names of audios
• tex_win - averaging window length in seconds (defauls to 3)
• tex_hop - hop in seconds between averaging windows (defaults to 1)
• offsets - list of values in seconds to shift the audio in time by, as a way of performing test-time augmentation (offers a robust way of measuring test performance)
• out_path - path to save features (defaults to ../../features/features_from_matlab/texwin_<tex_win value>/, relative to the current directory)