From 6bc657414d7a201398c142eecdb372ba5aff8944 Mon Sep 17 00:00:00 2001 From: Seppo Ingalsuo Date: Tue, 3 Oct 2023 15:33:49 +0300 Subject: [PATCH] Tools: Tune: dcblock: Create set of cut-off frequencies This patch modifies script example_dblock.m to create in addition to existing default coefficients blob with parameter R=0.98 a set of blobs those provide (-3 dB) cut-off frequencies 20, 30, 40, 50, 100, 200 Hz for 16 kHz and 48 kHz for various usages. Human understandable parameters for blobs helps to select the configuration for the needed dcblock usage. The parameter value R for given frequencies is calculated with iterative function dcblock_rval_calculate(). A closed form equation might be possible to derive from the transfer function. If such is found this function can be replaced with quicker equation -- or with more advanced faster converging iteration. The topology blob export functions are also modified to add comment line for exact build command. Signed-off-by: Seppo Ingalsuo --- tools/tune/common/tplg2_write.m | 8 +- tools/tune/common/tplg_write.m | 9 ++- tools/tune/dcblock/example_dcblock.m | 108 ++++++++++++++++++++++++--- 3 files changed, 114 insertions(+), 11 deletions(-) diff --git a/tools/tune/common/tplg2_write.m b/tools/tune/common/tplg2_write.m index 9453c5d7dd7b..1bb28b05e5c6 100644 --- a/tools/tune/common/tplg2_write.m +++ b/tools/tune/common/tplg2_write.m @@ -1,4 +1,4 @@ -function tplg2_write(fn, blob8, component, comment) +function tplg2_write(fn, blob8, component, comment, howto) % SPDX-License-Identifier: BSD-3-Clause % @@ -9,6 +9,9 @@ function tplg2_write(fn, blob8, component, comment) if nargin < 4 comment = 'Exported Control Bytes'; end +if nargin < 5 + howto = []; +end %% Check that blob length is multiple of 32 bits n_blob = length(blob8); @@ -23,6 +26,9 @@ function tplg2_write(fn, blob8, component, comment) fh = fopen(fn, 'w'); nl = 8; fprintf(fh, '# %s %s\n', comment, date()); +if ~isempty(howto) + fprintf(fh, '# %s\n', howto); +end fprintf(fh, 'Object.Base.data.\"%s\" {\n', component); fprintf(fh, '\tbytes \"\n'); for i = 1:nl:n_blob diff --git a/tools/tune/common/tplg_write.m b/tools/tune/common/tplg_write.m index 079aea77fd10..15692cfab295 100644 --- a/tools/tune/common/tplg_write.m +++ b/tools/tune/common/tplg_write.m @@ -1,8 +1,11 @@ -function tplg_write(fn, blob8, name, comment) +function tplg_write(fn, blob8, name, comment, howto) if nargin < 4 comment = 'Exported Control Bytes'; end +if nargin < 5 + howto = []; +end %% Pad blob length to multiple of four bytes n_orig = length(blob8); @@ -14,6 +17,9 @@ function tplg_write(fn, blob8, name, comment) fh = fopen(fn, 'w'); nl = 8; fprintf(fh, '# %s %s\n', comment, date()); +if ~isempty(howto) + fprintf(fh, '# %s\n', howto); +end fprintf(fh, 'CONTROLBYTES_PRIV(%s_priv,\n', name); fprintf(fh, '` bytes "'); for i = 1:nl:n_new @@ -33,5 +39,6 @@ function tplg_write(fn, blob8, name, comment) end fprintf(fh, ')\n'); fclose(fh); +fprintf('Blob size %d was written to file %s\n', n_new, fn); end diff --git a/tools/tune/dcblock/example_dcblock.m b/tools/tune/dcblock/example_dcblock.m index df8500473369..6ffa179e5485 100644 --- a/tools/tune/dcblock/example_dcblock.m +++ b/tools/tune/dcblock/example_dcblock.m @@ -1,16 +1,53 @@ function example_dcblock() +% Default blob, about 150 Hz cut-off @ 48 kHz +prm.fc = []; +prm.fs = []; +prm.R_coeffs = [0.98, 0.98, 0.98, 0.98, 0.98, 0.98, 0.98, 0.98]; +prm.id = "default"; +dcblock_blob_calculate(prm) + +% Generate a set configuration blobs for 16 and 48 kHz rate +% The selected high-pass cut-off frequencies are in range 20 - 200 Hz: +% 20, 30, 40, 50, 80, 100, and 200 Hz +% +% Select for applications one that is best tradeoff between DC level +% settle time and the lowest frequency that should pass without +% much attenuation. Cut-off frequency by definition is the point where +% the attenuation is 3.01 dB. + +prm.R_coeffs = []; +for fs = [16e3 48e3] + for fc = [20 30 40 50 80 100 200] + prm.id = sprintf("%dhz_%dkhz", round(fc), round(fs / 1000)); + prm.fs = fs; + prm.fc = fc; + dcblock_blob_calculate(prm) + end +end + +end + +function dcblock_blob_calculate(prm) + % Set the parameters here -tplg1_fn = "../../topology/topology1/m4/dcblock_coef_default.m4"; % Control Bytes File -tplg2_fn = "../../topology/topology2/include/components/dcblock/default.conf"; +tplg1_fn = sprintf("../../topology/topology1/m4/dcblock_coef_%s.m4", prm.id); % Control Bytes File +tplg2_fn = sprintf("../../topology/topology2/include/components/dcblock/%s.conf", prm.id); % Use those files with sof-ctl to update the component's configuration -blob3_fn = "../../ctl/ipc3/dcblock_coef.blob"; % Blob binary file -alsa3_fn = "../../ctl/ipc3/dcblock_coef.txt"; % ALSA CSV format file -blob4_fn = "../../ctl/ipc4/dcblock_coef.blob"; % Blob binary file -alsa4_fn = "../../ctl/ipc4/dcblock_coef.txt"; % ALSA CSV format file +blob3_fn = sprintf("../../ctl/ipc3/dcblock/coef_%s.blob", prm.id); % Blob binary file +alsa3_fn = sprintf("../../ctl/ipc3/dcblock/coef_%s.txt", prm.id); % ALSA CSV format file +blob4_fn = sprintf("../../ctl/ipc4/dcblock/coef_%s.blob", prm.id); % Blob binary file +alsa4_fn = sprintf("../../ctl/ipc4/dcblock/coef_%s.txt", prm.id); % ALSA CSV format file endian = "little"; -R_coeffs = [0.98, 0.98, 0.98, 0.98, 0.98, 0.98, 0.98, 0.98]; + +if isempty(prm.fc) + R_coeffs = prm.R_coeffs; +else + channels = 8; + R = dcblock_rval_calculate(prm.fs, prm.fc); + R_coeffs = R * ones(1, channels); +end addpath ./../common @@ -18,11 +55,15 @@ function example_dcblock() blob8_ipc4 = dcblock_build_blob(R_coeffs, endian, 4); % Generate output files -tplg_write(tplg1_fn, blob8, "DCBLOCK"); +tplg_write(tplg1_fn, blob8, "DCBLOCK", ... + "Exported with script example_dcblock.m", ... + "cd tools/tune/dcblock; octave example_dcblock.m"); blob_write(blob3_fn, blob8); alsactl_write(alsa3_fn, blob8); -tplg2_write(tplg2_fn, blob8_ipc4, "dcblock_config", "Exported with script example_dcblock.m"); +tplg2_write(tplg2_fn, blob8_ipc4, "dcblock_config", ... + "Exported with script example_dcblock.m" , ... + "cd tools/tune/dcblock; octave example_dcblock.m"); blob_write(blob4_fn, blob8_ipc4); alsactl_write(alsa4_fn, blob8_ipc4); @@ -36,3 +77,52 @@ function example_dcblock() rmpath ./../common end + +% Finds with iterative search parameter R for given cutoff frequency +function R = dcblock_rval_calculate(fs, fc_target) + +if (fc_target / fs < 10 / 48e3 || fc_target / fs > 1000 / 48e3) + error("Illegal fc_target"); +end + +h_target = 1 / sqrt(2); % -3.01 dB +R = 0.5; +R_step = 0.005; +sign = 1; +w = 2 * pi * fc_target / fs; +j = sqrt(-1); +z = exp(j * w); + +% Iteration 0 +h = (1 - z^-1) / (1 - R * z^-1); +err_prev = (h_target - abs(h))^2; +R = R + sign * R_step; + +% Do more iterations +for n = 1 : 200 + h = (1 - z^-1) / (1 - R * z^-1); + err = (h_target - abs(h))^2; + if (err > err_prev) + sign = -sign; + R_step = R_step / 2; + end + R = R + sign * R_step; + err_prev = err; +end + +% Sane result? +if R < eps || R > 1 - eps + error("Calculate of R iteration failed"); +end + +% Sane high-pass function? +f = [1 fc_target fs/2]; +b = [ 1 -1 ]; a = [ 1 -R ]; +h = freqz(b, a, f, fs); +h_db = 20*log10(abs(h)); +err_hfc = abs(20*log10(1/sqrt(2)) - h_db(2)); +if err_hfc > 0.01 || h_db(1) > -10 || h_db(3) < 0 || h_db(3) > 1 + error("Failed high-pass response"); +end + +end