mathieu@14: function scale = adjustScaleForEBR (fg, bg, offset, targetEBR, snrType, eps)
mathieu@14: % Computes the value of 'scale' such that fg*scale has a given EBR
mathieu@14: % relatively to bg at position 'offset'.
mathieu@14: % ebrType is used to select what kind of EBR should be considered:
mathieu@14: % 1 - standard temporal ebr over whole length of sample
mathieu@14: % 2 - max of standard temporal ebr over 1/4s windows
mathieu@14: % 3 - more to come ?
mathieu@14: % eps is the epsilon used to check for convergence; optional, defaults to
mathieu@14: % 0.01
mathieu@14: 
mathieu@14: % This program was written by Mathias Rossignol & Grégoire Lafay
mathieu@14: % is Copyright (C) 2015 IRCAM <http://www.ircam.fr>
mathieu@14: %
mathieu@14: % This program is free software: you can redistribute it and/or modify it
mathieu@14: % under the terms of the GNU General Public License as published by the Free
mathieu@14: % Software Foundation, either version 3 of the License, or (at your option)
mathieu@14: % any later version.
mathieu@14: %
mathieu@14: % This program is distributed in the hope that it will be useful, but
mathieu@14: % WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
mathieu@14: % or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
mathieu@14: % for more details.
mathieu@14: %
mathieu@14: % You should have received a copy of the GNU General Public License along
mathieu@14: % with this program.  If not, see <http://www.gnu.org/licenses/>.
mathieu@14: 
mathieu@14: if (nargin == 5) eps = 0.01; end
mathieu@14: %if (targetSNR <= 0) targetSNR = exp(targetSNR); end
mathieu@14: prevScale = 1;
mathieu@14: scale = 1;
mathieu@14: ebrFunc=@ebr;
mathieu@14: if (snrType==2) ebrFunc=@maxWindowEBR; end
mathieu@14: count = 0;
mathieu@14: while (ebrFunc(fg, bg, offset, scale) > targetEBR && count < 100)
mathieu@14:     prevScale = scale;
mathieu@14:     scale = scale/2;
mathieu@14:     count = count+1;
mathieu@14: end
mathieu@14: if (count == 100)
mathieu@14:     msg = ['Max count, stage 1, scale = ', num2str(scale), ' - ', num2str(ebrFunc(fg, bg, offset, scale)), ' - ', num2str(ebrFunc(fg, bg, offset, prevScale)), ' - ', num2str(ebrFunc(fg, bg, offset, 1))];
mathieu@14:     error(msg)
mathieu@14: end
mathieu@14: count=0;
mathieu@14: while (ebrFunc(fg, bg, offset, scale) < targetEBR && count < 100)
mathieu@14:     prevScale = scale;
mathieu@14:     scale = scale*2;
mathieu@14:     count = count+1;
mathieu@14: end
mathieu@14: if (count == 100)
mathieu@14:     msg = ['Max count, stage 2, scale = ', num2str(scale)];
mathieu@14:     error(msg)
mathieu@14: end
mathieu@14: count=0;
mathieu@14: if (scale<prevScale)
mathieu@14:     a = scale;
mathieu@14:     b = prevScale;
mathieu@14: else
mathieu@14:     a=prevScale;
mathieu@14:     b=scale;
mathieu@14: end
mathieu@14: delta = ebrFunc(fg, bg, offset, (a+b)/2) - targetEBR;
mathieu@14: while (abs(delta) > eps && count < 100)
mathieu@14:     if (delta>0)
mathieu@14:         b = (a+b)/2;
mathieu@14:     else
mathieu@14:         a = (a+b)/2;
mathieu@14:     end
mathieu@14:     delta = ebrFunc(fg, bg, offset, (a+b)/2) - targetEBR;
mathieu@14:     count = count+1;
mathieu@14: end
mathieu@14: if (count == 100)
mathieu@14:     msg = ['Max count, stage 3, scale = ', num2str(a)];
mathieu@14:     error(msg)
mathieu@14: end
mathieu@14: scale = (a+b)/2;
mathieu@14: end