Clipping, also known as saturation, is a comon phenomenon leading to sometimes seriously distorted audio recordings. Declipping consists in performing the inverse process, to restore saturated audio recordings and improve their quality.
Original signal
Clipped signal
Declipped signal using A-SPADE
SPADE, the SParse Audio DEclipper
SPADE is a declipping algorithm developed by PANAMA (a joint project-team between INRIA and CNRS). It is based on on the expression of declipping as a linear inverse problem and the use of analysis (A-SPADE) or synthesis (S-SPADE) sparse regularization in the time-frequency domain.
To the best of our knowledge SPADE achieves state-of-the-art declipping quality.
S. Kitic, N. Bertin and R. Gribonval. Audio Declipping by Cosparse Hard Thresholding. In iTwist – 2nd international – Traveling Workshop on Interactions between Sparse models and Technology, Namur, 2014.
Listen and compare
A good way to get an idea of the declipping performance of SPADE is to listen to some examples.
Results for different input clipping levels
Click on the examples below to compare A-SPADE with another recent algorithm, Consistent IHT, as well as with the Adobe Audition DeClipper (TM) software.
Two example audio tracks are clipped to prescribed SDR (Signal to Distortion Ratio) values and processed by the different algorithms. The original (unclipped) tracks and the clipped versions are given as references along with the achieved declipping results.
Ten example audio tracks are clipped to 3dB SDR and processed by the different algorithms. The original (unclipped) tracks and the clipped versions are given as references along with the processing results achieved using another commercial software.
Audio examples
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Original
Clipped
Commercial software
Consistent IHT
A-SPADE
S-SPADE
Test it with your own files
To test A-SPADE, you can either use Inria’s software demonstration platform, A||go, to test it on the web, or download its Matlab implementation that allows reproducing the experiments of the paper A-SPADE.
Test A-SPADE from your web browser
To test the online demo of A-SPADE on A||go, Inria’s software demonstration platform, you have first to Create an account on the A||go platform if you do not have one already. Then choose between using A-SPADE from the a||go platform (to have all parameters and logs available) or using the light interface on this web page.
This demonstration version handles most audio files formats (.wav, .mp3, .mp4, .m4a, .ogg, .flac) and all common bit depth values.
Limitation: This online demo only processes 30 seconds of the two first channels of the provided clipped input file. If you are interested by other use cases, please contact Pascal Carrivain and Rémi Gribonval firstname.lastname@inria.fr.
Declipping process duration: The declipping process can last from a few seconds to a few minutes depending on sampling frequency, chosen preset and number of channels.
Warning: this software version is limited to 64 bits per samples natively clipped .wav files (input files have to be clipped in 64 bits PCM and not transcoded from lossy format for this software version). This limitation is removed in the online version presented below.
Licence
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This software is available under the BSD-3-Clause License (https://opensource.org/licenses/BSD-3-Clause)
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3-Clause BSD License
Copyright <2016><INRIA – CNRS><Srdan Kitic>
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
(i) Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
(ii) Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
(iii) Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
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