REPET-Matlab

REPeating Pattern Extraction Technique (REPET) in Matlab for audio source separation.

REPeating Pattern Extraction Technique (REPET) in Matlab for audio source separation.

Repetition is a fundamental element in generating and perceiving structure. In audio, mixtures are often composed of structures where a repeating background signal is superimposed with a varying foreground signal (e.g., a singer overlaying varying vocals on a repeating accompaniment or a varying speech signal mixed up with a repeating background noise). On this basis, we present the REpeating Pattern Extraction Technique (REPET), a simple approach for separating the repeating background from the non-repeating foreground in an audio mixture. The basic idea is to find the repeating elements in the mixture, derive the underlying repeating models, and extract the repeating background by comparing the models to the mixture. Unlike other separation approaches, REPET does not depend on special parameterizations, does not rely on complex frameworks, and does not require external information. Because it is only based on repetition, it has the advantage of being simple, fast, blind, and therefore completely and easily automatable.

Files:
- repet.m: Matlab class with the REPET methods.
- examples.ipynb: Jupyter notebook with some examples.
- audio_file.wav: audio file used for the examples.

Functions:
- original - Compute the original REPET.
- extended - Compute REPET extended.
- adaptive - Compute the adaptive REPET.
- sim - Compute REPET-SIM.
- simonline - Compute the online REPET-SIM.

original
The original REPET aims at identifying and extracting the repeating patterns in an audio mixture, by estimating a period of the underlying repeating structure and modeling a segment of the periodically repeating background.
background_signal = repet.original(audio_signal, sampling_frequency);

extended
The original REPET can be easily extended to handle varying repeating structures, by simply applying the method along time, on individual segments or via a sliding window.
background_signal = repet.extended(audio_signal, sampling_frequency);

adaptive
The original REPET works well when the repeating background is relatively stable (e.g., a verse or the chorus in a song); however, the repeating background can also vary over time (e.g., a verse followed by the chorus in the song). The adaptive REPET is an extension of the original REPET that can handle varying repeating structures, by estimating the time-varying repeating periods and extracting the repeating background locally, without the need for segmentation or windowing.
background_signal = repet.adaptive(audio_signal, sampling_frequency);

sim
The REPET methods work well when the repeating background has periodically repeating patterns (e.g., jackhammer noise); however, the repeating patterns can also happen intermittently or without a global or local periodicity (e.g., frogs by a pond). REPET-SIM is a generalization of REPET that can also handle non-periodically repeating structures, by using a similarity matrix to identify the repeating elements.
background_signal = repet.sim(audio_signal, sampling_frequency);

simonline
REPET-SIM can be easily implemented online to handle real-time computing, particularly for real-time speech enhancement. The online REPET-SIM simply processes the time frames of the mixture one after the other given a buffer that temporally stores past frames.
background_signal = repet.simonline(audio_signal, sampling_frequency);

Author:
- Zafar Rafii
- [e-mail]
- http://zafarrafii.com
- https://github.com/zafarrafii
- https://www.linkedin.com/in/zafarrafii/

See also: https://github.com/zafarrafii/REPET-Matlab