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Sparse Audio Models For Inverse Audio Problems Rmi Gribonval INRIA Rennes - Bretagne Atlantique, France remi.gribonval@inria.fr Outline Inverse problems in audio processing audio inpainting source localization Learning


  1. Sparse Audio Models For Inverse Audio Problems Rémi Gribonval INRIA Rennes - Bretagne Atlantique, France remi.gribonval@inria.fr

  2. Outline • Inverse problems in audio processing ✓ audio inpainting ✓ source localization • Learning low-dimensional audio models ✓ dictionaries ... R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 2

  3. Contributors • Audio inpainting small-project.eu ✓ A. Adler, N. Bertin, V. Emiya, M. Elad, C.Guichaoua, M. Jafari, M. Plumbley • Source localization ✓ S. Nam echange.inria.fr • Dictionary learning ✓ F. Bach, R. Jenatton, K. Schnass R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 3

  4. Audio inpainting with A. Adler, V. Emiya, M. Elad, M. Jafari, M. Plumbley R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012-

  5. Image Inpainting Observed image Inpainted image R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 5

  6. Audio Inpainting ? Holes (Packet Loss) Clipping 1 Amplitude 0 − 1 0 0.01 0.02 0.03 Time (s) Limited bandwidth Clicks 8000 Frequency (Hz) 6000 Amplitude 1 4000 0 − 1 2000 0 0.01 0.02 0.03 0 Time (s) 0.1 0.2 0.3 0.4 Time (s) R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 6

  7. Audio Inpainting ? Clipping 1 Amplitude 0 − 1 0 0.01 0.02 0.03 Time (s) R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 6

  8. Declipping as a linear inverse problem • Original (unknown) samples x • Clipped (observed) samples y • Subset of reliable samples y reliable • Linear inverse problem x M y reliable = R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 7

  9. Inverse problems & signal models Observation Domain Need for a model = prior knowledge R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 8

  10. Sparse audio models • Time domain • Time-frequency domain (Black = zero) R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 9

  11. Mathematical expression • Signal / image = high dimensional vector x ∈ R d • Model = linear combination of basis vectors (ex: time-frequency atoms, wavelets ) Dictionary of atoms X x ≈ z k d k = Dz (Mallat & Zhang 93) k • Sparsity = small L0 (quasi)-norm | z k | 0 = card { k, z k � = 0 } X ⇥ z ⇥ 0 = k R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 10

  12. CoSparse models and inverse problems Observation Domain R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 11

  13. Audio Declipping • Model ✓ sparsity in time-frequency dictionary x = Dz • Algorithm: ✓ find sparse coefficients such that y = MD ˆ z ˆ z (Orthonormal) Matching Pursuit ( Mallat & Zhang 93 ) ✦ ✓ + ensure compatibility with clipping constraint Convex optimization ✦ ✓ estimate x = D ˆ z ˆ 0.5 Amplitude 0 − 0.5 0 0.01 0.02 0.03 0.04 0.05 time (s) A. Adler, V. Emiya, M. Jafari, M. Elad, R. Gribonval and M. D. Plumbley, Audio Inpainting, IEEE Trans Audio Speech and Language Proc., 2012 R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 12

  14. Audio Declipping • Model ✓ sparsity in time-frequency dictionary x = Dz • Algorithm: ✓ find sparse coefficients such that y = MD ˆ z ˆ z (Orthonormal) Matching Pursuit ( Mallat & Zhang 93 ) ✦ ✓ + ensure compatibility with clipping constraint Convex optimization ✦ ✓ estimate x = D ˆ z ˆ 0.5 Amplitude 0 − 0.5 0 0.01 0.02 0.03 0.04 0.05 time (s) A. Adler, V. Emiya, M. Jafari, M. Elad, R. Gribonval and M. D. Plumbley, Audio Inpainting, IEEE Trans Audio Speech and Language Proc., 2012 R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 12

  15. Audio Declipping • Model ✓ sparsity in time-frequency dictionary x = Dz • Algorithm: ✓ find sparse coefficients such that y = MD ˆ z ˆ z (Orthonormal) Matching Pursuit ( Mallat & Zhang 93 ) ✦ ✓ + ensure compatibility with clipping constraint Convex optimization ✦ ✓ estimate x = D ˆ z ˆ 0.5 Amplitude 0 Clipped − 0.5 0 0.01 0.02 0.03 0.04 0.05 time (s) A. Adler, V. Emiya, M. Jafari, M. Elad, R. Gribonval and M. D. Plumbley, Audio Inpainting, IEEE Trans Audio Speech and Language Proc., 2012 R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 12

  16. Audio Declipping • Model ✓ sparsity in time-frequency dictionary x = Dz • Algorithm: ✓ find sparse coefficients such that y = MD ˆ z ˆ z (Orthonormal) Matching Pursuit ( Mallat & Zhang 93 ) ✦ ✓ + ensure compatibility with clipping constraint Convex optimization ✦ ✓ estimate x = D ˆ z ˆ 0.5 Amplitude 0 Clipped Declipped − 0.5 0 0.01 0.02 0.03 0.04 0.05 time (s) A. Adler, V. Emiya, M. Jafari, M. Elad, R. Gribonval and M. D. Plumbley, Audio Inpainting, IEEE Trans Audio Speech and Language Proc., 2012 R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 12

  17. Audio Declipping • Model ✓ sparsity in time-frequency dictionary x = Dz • Algorithm: ✓ find sparse coefficients such that y = MD ˆ z ˆ z (Orthonormal) Matching Pursuit ( Mallat & Zhang 93 ) ✦ ✓ + ensure compatibility with clipping constraint Convex optimization ✦ ✓ estimate x = D ˆ z ˆ 0.5 Amplitude 0 Clipped Original Declipped − 0.5 0 0.01 0.02 0.03 0.04 0.05 time (s) A. Adler, V. Emiya, M. Jafari, M. Elad, R. Gribonval and M. D. Plumbley, Audio Inpainting, IEEE Trans Audio Speech and Language Proc., 2012 R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 12

  18. Audio Declipping • Model ✓ sparsity in time-frequency dictionary x = Dz • Algorithm: ✓ find sparse coefficients such that y = MD ˆ z ˆ z (Orthonormal) Matching Pursuit ( Mallat & Zhang 93 ) ✦ ✓ + ensure compatibility with clipping constraint Convex optimization ✦ ✓ estimate x = D ˆ z ˆ 0.5 Amplitude 0 Clipped Original Declipped − 0.5 see also talk by B. Mailhé 0 0.01 0.02 0.03 0.04 0.05 time (s) A. Adler, V. Emiya, M. Jafari, M. Elad, R. Gribonval and M. D. Plumbley, Audio Inpainting, IEEE Trans Audio Speech and Language Proc., 2012 R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 12

  19. Source localization with S. Nam R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012-

  20. Localization with «few» microphones • Possible goals ✓ localize emitting sources ✓ reconstruct emitted signals ✓ extrapolate acoustic field • Linear inverse problem y = Mx (discretized) time-series ∈ R N spatio-temporal recorded ∈ R m acoustic field at sensors • Need a model R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 14

  21. Physics-driven design of model • Pressure field p ( � r, t ) • Wave equation on a domain c 2 ∂ 2 r ∈ ˙ ( ∆ p − 1 ∂ t 2 p )( � r, t ) = s ( � r, t ) , � D • Boundary + initial conditions , e.g. � p � n ( ⇥ r, t ) = 0 , ⇥ r ∈ � D R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 15

  22. Physics-driven design of model Discretization • Pressure field p ( � r, t ) x • Wave equation on a domain c 2 ∂ 2 r ∈ ˙ ( ∆ p − 1 ∂ t 2 p )( � r, t ) = s ( � r, t ) , � } D • Boundary + initial conditions , e.g. Ω x = z � p sources � n ( ⇥ r, t ) = 0 , ⇥ r ∈ � D & boundaries R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 15

  23. Group sparse source model • Few non-moving sources = spatially sparse time t z � r,t space � r R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 16

  24. Group sparse regularization • Inverse problem y = Mx • Sparse regularization with mixed norm 1 2 k y � Mx k 2 2 + λ k Ω x k 1 , 2 x = arg min ˆ x Promotes group sparsity, cf Kowalski & Torresani 2009, Eldar & Mishali ✦ 2009, Baraniuk & al 2010, Jenatton & al 2011 R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 17

  25. Sparse Field Reconstruction • Setting • Results ✓ 2D+t vibrating plate 77x77 ✓ 2 sources, random location ✓ 6 microphones, random location ✓ known complex boundaries ✓ ground truth generated with naive discretization Ground truth Sparse reconstruction S. Nam and R. Gribonval. Physics-driven structured cosparse modeling for source localization, ICASSP 2012 R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 18

  26. Sparse Field Reconstruction • Setting • Results ✓ 2D+t vibrating plate 77x77 ✓ 2 sources, random location ✓ 6 microphones, random location ✓ known complex boundaries ✓ ground truth generated with naive discretization Ground truth Sparse reconstruction S. Nam and R. Gribonval. Physics-driven structured cosparse modeling for source localization, ICASSP 2012 R. GRIBONVAL - Workshop on Sparsity, Compressed Sensing and Applications November 5th 2012 18

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