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add original MATLAB scripts used to develop AGC algorithms
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‎docs/MATLAB/OpossumAGC.m

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%% OpossumAGC Automatic gain control with hysteresis control of noisy signals
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%
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% Copyright (c) 2017-2021 Winry R. Litwa-Vulcu. All rights reserved.
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%
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% This program is free software: you can redistribute it and/or modify
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% it under the terms of the GNU General Public License as published by
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% the Free Software Foundation, either version 3 of the License, or
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% (at your option) any later version.
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%
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% This program is distributed in the hope that it will be useful,
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% but WITHOUT ANY WARRANTY; without even the implied warranty of
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% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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% GNU General Public License for more details.
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%
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% You should have received a copy of the GNU General Public License
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% along with this program. If not, see <https://www.gnu.org/licenses/>.
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clc; close all hidden; clearvars; %drawnow; pause(0.05);
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volume = 34;
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audio_level = 3452;
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range_mB = 600;
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range_step_mB = 50;
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noiseline = @(start, stop, len, noiselevel) rot90((randn(1, len) .* noiselevel) ...
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+ linspace(start, stop, len), -1);
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segment_length = @(x) round(abs(x * randn));
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raw_audio_level = ([noiseline(3000, 4000, segment_length(1001), 30)
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noiseline(4000, 2800, segment_length(1001), 40)
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noiseline(2800, 6500, segment_length(1001), 50)
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noiseline(6500, 7000, segment_length(1001), 45)
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noiseline(7000, 6300, segment_length(1001), 55)
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noiseline(6300, 4000, segment_length(1001), 50)
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noiseline(4000, 4500, segment_length(1001), 35)
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noiseline(4500, 1800, segment_length(1001), 30)
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noiseline(1800, 1700, segment_length(1001), 20)
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noiseline(1700, 3600, segment_length(1001), 30)]);
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mean_audio_level = zeros(size(raw_audio_level));
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mbuff = raw_audio_level(1) * ones(1, 32);
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buff_indx_32 = 1;
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for k = 1:length(raw_audio_level)
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if (buff_indx_32 > 32)
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buff_indx_32 = 1;
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end
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if (raw_audio_level(k) > mbuff(buff_indx_32))
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mbuff(buff_indx_32) = mbuff(buff_indx_32) ...
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+ (raw_audio_level(k) - mbuff(buff_indx_32)) / 2;
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else
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mbuff(buff_indx_32) = mbuff(buff_indx_32) .* (31/32);
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end
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mean_audio_level(k) = mean(mbuff);
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buff_indx_32 = buff_indx_32 + 1;
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end
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dB_CoefTable = [2053, 2175, 2303, 2440, 2584;
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2738, 2900, 3072, 3254, 3446;
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3651, 3867, 4096, 4339, 4596;
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4868, 5157, 5462, 5786, 6129;
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6492, 6876, 7284, 7715, 8173];
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levels_raw = bitshift(uint32(audio_level .* dB_CoefTable), -12);
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[v_map, a, b, C] = com.programming.OpossumVolumeMap(volume, range_mB, range_step_mB);
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v = b:-1:a
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C
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%VolOut_absolute_mB = fliplr(rot90(reshape(c(v_map - a + 1), 5, 5), -1))
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dBFastRelativeLevel_mB = levels_raw
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VolOut_setting = fliplr(rot90(reshape(v_map - 1, 5, 5), -1))
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% ##################################################################################################
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[vol, volOut] = deal(volume);
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DB_FAST_COEFFICIENT_COUNT = numel(dB_CoefTable);
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levels_raw = sort(double(levels_raw(:)));
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indx = 1 * ones(length(raw_audio_level), 1);
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indx(1) = 13;
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prev_indx = 1;
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for m = 2:length(raw_audio_level)
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for k=DB_FAST_COEFFICIENT_COUNT:-1:1
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if (levels_raw(k) < mean_audio_level(m))
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if (abs(prev_indx - (k)) > 1)
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indx(m) = (k);
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prev_indx = indx(m);
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break;
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else
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indx(m) = prev_indx;
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break;
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end
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end
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end
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end
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H = plotyy((1:length(raw_audio_level))./10, raw_audio_level, ...
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(1:length(raw_audio_level))./10, v_map(indx));
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hold on;
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plot(H(1), (1:length(raw_audio_level))./10, mean_audio_level, 'r');
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L = line([zeros(1, 25); length(raw_audio_level) .* ones(1, 25)], [levels_raw.'; levels_raw.']);
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set(L(13), 'lineWidth', 3);
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set(H(1), 'YLim', [min(levels_raw), max(levels_raw)]);
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set(H(2), 'YLim', [a, b]);
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set(H(2), 'YGrid', 'on', 'YMinorGrid', 'off', 'YTick', 1, 'YMinorTick', 'on', 'YTickMode', 'auto');
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A2 = get(H(2), 'Children');
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set(A2(1), 'LineWidth', 2);
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%figure(2); plot(indx)

‎docs/MATLAB/OpossumVolumeMap.m

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function [v_map, a, b, C] = OpossumVolumeMap(volume, range_mB, range_step_mB)
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%% OpossumVolumeMap generates a volume map v_map for a given input volume and range
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%
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% Copyright (c) 2017-2021 Winry R. Litwa-Vulcu. All rights reserved.
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%
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% This program is free software: you can redistribute it and/or modify
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% it under the terms of the GNU General Public License as published by
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% the Free Software Foundation, either version 3 of the License, or
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% (at your option) any later version.
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%
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% This program is distributed in the hope that it will be useful,
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% but WITHOUT ANY WARRANTY; without even the implied warranty of
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% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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% GNU General Public License for more details.
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%
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% You should have received a copy of the GNU General Public License
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% along with this program. If not, see <https://www.gnu.org/licenses/>.
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volume(volume < 1) = 1;
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volume(volume > 64) = 64;
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offset_mB = linspace(0, 2 * range_mB, round((2 * range_mB)/50) + 1);
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gain_mB = [-10950; -9290; -9030; -8680;
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-8430; -8080; -7830; -7470;
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-7220; -6870; -6620; -6270;
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-6020; -5670; -5420; -5060;
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-4810; -4560; -4370; -4210;
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-3960; -3760; -3600; -3340;
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-3150; -2980; -2720; -2520;
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-2350; -2160; -1970; -1750;
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-1640; -1540; -1440; -1310;
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-1200; -1090; -990; -890;
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-710; -600; -500; -340;
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-190; -50; 50; 120;
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160; 200; 240; 290;
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340; 390; 440; 490;
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540; 590; 650; 700;
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760; 820; 880; 950];
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% determine the levels within the range
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a = 1;
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b = 64;
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if (volume ~= 1)
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for k = volume-1:-1:1
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if ((gain_mB(k) - gain_mB(volume)) < -range_mB);
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a = k + 1;
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break;
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end
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end
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end
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if (volume ~= numel(gain_mB))
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for k = volume+1:numel(gain_mB);
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if ((gain_mB(k) - gain_mB(volume)) > range_mB)
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b = k - 1;
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break;
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end
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end
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end
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v = b:-1:a;
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sizeof_v = numel(v);
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c_normal = (gain_mB(v) - gain_mB(volume));
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v_map = zeros(25, 1);
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skip_zero_indx = 0;
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map_indx = 1;
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for k=1:numel(offset_mB)
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if (c_normal(map_indx) == 0)
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skip_zero_indx = 1;
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end
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if ((map_indx + skip_zero_indx) <= sizeof_v)
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if ((range_mB - c_normal(map_indx + skip_zero_indx)) < ((k - 1) * range_step_mB))
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map_indx = map_indx + 1;
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end
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end
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v_map(k) = v(map_indx);
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end
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C = [gain_mB(v), c_normal, (range_mB - c_normal)];
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end

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