144 lines
4.1 KiB
Matlab
Executable File
144 lines
4.1 KiB
Matlab
Executable File
%/******************************************************************************\
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% * Copyright (c) 2004-2006
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% *
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% * Author(s):
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% * Volker Fischer
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% *
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%\******************************************************************************/
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function resamplefilter()
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% Number of taps per poly phase for different resampling types
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GlobalNoTaps = 4;%12; % use global value for all types
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NoTapsP2 = GlobalNoTaps; % 24 kHz
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NoTapsP3_2 = GlobalNoTaps; % 32 kHz
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NoTapsP12_7 = GlobalNoTaps; % 28 kHz
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NoTapsP1 = GlobalNoTaps; % 48 kHz
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% Filter for ratio 2 -----------------------------------------------------------
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% I and D
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I2 = 2;
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D2 = 1;
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% filter design
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h2 = DesignFilter(NoTapsP2, I2);
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% Filter for ratio 3 / 2 -------------------------------------------------------
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% I and D
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I3_2 = 3;
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D3_2 = 2;
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% filter design
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h3_2 = DesignFilter(NoTapsP3_2, I3_2);
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% Filter for ratio 12 / 7 ------------------------------------------------------
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% I and D
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I12_7 = 12;
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D12_7 = 7;
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% filter design
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h12_7 = DesignFilter(NoTapsP12_7, I12_7);
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% Filter for ratios close to 1 -------------------------------------------------
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% Fixed for sample-rate conversiones of R ~ 1
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I1 = 10; % D = I in this mode
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% MMSE filter-design and windowing
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h1 = DesignFilter(NoTapsP1, I1);
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% Export coefficiants to file ****************************************
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fid = fopen('resamplefilter.h', 'w');
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fprintf(fid, '/* Automatically generated file with MATLAB */\n');
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fprintf(fid, '/* File name: "ResampleFilter.m" */\n');
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fprintf(fid, '/* Filter taps in time-domain */\n\n');
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fprintf(fid, '#ifndef _RESAMPLEFILTER_H_\n');
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fprintf(fid, '#define _RESAMPLEFILTER_H_\n\n');
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fprintf(fid, '#define NUM_TAPS_PER_PHASE2 ');
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fprintf(fid, int2str(NoTapsP2));
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fprintf(fid, '\n');
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fprintf(fid, '#define NUM_TAPS_PER_PHASE3_2 ');
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fprintf(fid, int2str(NoTapsP3_2));
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fprintf(fid, '\n');
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fprintf(fid, '#define NUM_TAPS_PER_PHASE12_7 ');
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fprintf(fid, int2str(NoTapsP12_7));
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fprintf(fid, '\n');
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fprintf(fid, '#define NUM_TAPS_PER_PHASE1 ');
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fprintf(fid, int2str(NoTapsP1));
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fprintf(fid, '\n');
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fprintf(fid, '#define INTERP_I_2 ');
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fprintf(fid, int2str(I2));
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fprintf(fid, '\n');
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fprintf(fid, '#define DECIM_D_2 ');
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fprintf(fid, int2str(D2));
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fprintf(fid, '\n');
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fprintf(fid, '#define INTERP_I_3_2 ');
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fprintf(fid, int2str(I3_2));
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fprintf(fid, '\n');
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fprintf(fid, '#define DECIM_D_3_2 ');
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fprintf(fid, int2str(D3_2));
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fprintf(fid, '\n');
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fprintf(fid, '#define INTERP_I_12_7 ');
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fprintf(fid, int2str(I12_7));
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fprintf(fid, '\n');
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fprintf(fid, '#define DECIM_D_12_7 ');
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fprintf(fid, int2str(D12_7));
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fprintf(fid, '\n');
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fprintf(fid, '#define INTERP_DECIM_I_D1 ');
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fprintf(fid, int2str(I1));
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fprintf(fid, '\n');
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fprintf(fid, '\n\n');
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% Write filter taps
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fprintf(fid, '\n// Filter for ratio 2\n');
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ExportFilterTaps(fid, 'fResTaps2[INTERP_I_2 * DECIM_D_2 * NUM_TAPS_PER_PHASE2]', h2);
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fprintf(fid, '\n// Filter for ratio 3 / 2\n');
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ExportFilterTaps(fid, 'fResTaps3_2[INTERP_I_3_2 * DECIM_D_3_2 * NUM_TAPS_PER_PHASE3_2]', h3_2);
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fprintf(fid, '\n// Filter for ratio 12 / 7\n');
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ExportFilterTaps(fid, 'fResTaps12_7[INTERP_I_12_7 * DECIM_D_12_7 * NUM_TAPS_PER_PHASE12_7]', h12_7);
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fprintf(fid, '// Filter for ratios close to 1\n');
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ExportFilterTaps(fid, 'fResTaps1[INTERP_DECIM_I_D1 * NUM_TAPS_PER_PHASE1]', h1);
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fprintf(fid, '\n#endif /* _RESAMPLEFILTER_H_ */\n');
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fclose(fid);
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return;
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function [h] = DesignFilter(NoTapsPIn, I)
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% number of taps, consider interpolation factor
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NoTapsP = NoTapsPIn * I;
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% Cut-off frequency (normlized)
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fc = 0.97 / I;
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% MMSE filter design with Kaiser window, consider interpolation factor
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h = I * firls(NoTapsP - 1, [0 fc fc 1], [1 1 0 0]) .* kaiser(NoTapsP, 5)';
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return;
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function ExportFilterTaps(f, name, h)
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% Write filter taps
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fprintf(f, ['static float ' name ' = {\n']);
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fprintf(f, ' %.20ff,\n', h(1:end - 1));
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fprintf(f, ' %.20ff\n', h(end));
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fprintf(f, '};\n\n');
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return;
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