EQ Tool: Add calibration data import

This patch adds capability to apply for capture microphone calibration
data (ASCII text lines with Hz, dB values). The calibration data file
name needs to be edited into configuration file mls_rec_config.txt. Such
calibration data is provided by several inexpensive USB measurement
microphones manufacturers.

Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>

tune/eq/mls_freq_resp.m

@@ -169,6 +169,8 @@ fprintf('Done.\n');
 
 [f, m_db,  b] = mls_calc_resp(csvfn, mlsfn, measfn, t_tot, np, f_lo, f_hi);
 
+[f, m_db] = apply_mic_calibration(f, m_db, rec_cfg);
+
 figure
 idx = find(f>1e3, 1, 'first') - 1;
 m_db_align = m_db - m_db(idx);
@@ -273,12 +275,89 @@ function rec = meas_remote_rec_config(fs, fmt)
 			     rec.nch, fmt, fs);
 
 	fprintf('\nThe setttings for remote capture are\n');
-	fprintf('Use ssh   : %d\n', rec.ssh);
-	fprintf('User      : %s\n', rec.user);
-	fprintf('Directory : %s\n', rec.dir);
-	fprintf('Device    : %s\n', rec.dev);
-	fprintf('format    : %s\n', rec.fmt);
-	fprintf('Channels  : %d\n', rec.nch);
+	fprintf('Use ssh          : %d\n', rec.ssh);
+	fprintf('User             : %s\n', rec.user);
+	fprintf('Directory        : %s\n', rec.dir);
+	fprintf('Device           : %s\n', rec.dev);
+	fprintf('format           : %s\n', rec.fmt);
+	fprintf('Channels         : %d\n', rec.nch);
+	fprintf('Calibration Data : %s\n', rec.cal);
+
+	if length(rec.cal) > 0
+		if exist(rec.cal, 'file')
+			[rec.cf, rec.cm, rec.sens, rec.cs] = get_calibration(rec.cal);
+		else
+			error('The calibration file does not exist');
+		end
+	else
+		rec.cf = [];
+		rec.cm = [];
+		rec.sens = [];
+		rec.cs = '';
+	end
+end
+
+% The syntax of ASCII text calibration data is such that first line is
+% text string sometimes within "" or text line about Sensitivity. Such
+% lines are read and stored to description text. The sensitivty is extracted
+% and printed if success but currently it is not utilized by the code.
+%
+% The next lines are <frequency Hz> <magnitude decibels> for
+% measurement data for microphone. If there are more than two numbers
+% per line the other than two first columns are ignored. This code
+% applies inverse of calibration data for measured response calibration.
+
+function [f, m, sens, desc] = get_calibration(fn)
+	fh = fopen(fn, 'r');
+	if fh < 0
+		error('Cannot open calibration data file');
+	end
+	n = 1;
+	f = [];
+	m = [];
+	sens =[];
+	desc = '';
+	str = fgets(fh);
+	idx = findstr(str, '"');
+	while length(idx) > 0
+		line = str(idx(1)+1:idx(2)-1);
+		desc = sprintf('%s%s ', desc, line);
+		str = fgets(fh);
+		idx = findstr(str, '"');
+	end
+	if length(strfind(str, 'Sens'))
+		desc = str;
+		str = fgets(fh);
+	end
+	while str ~= -1
+		d=sscanf(str,'%f');
+		f(n) = d(1);
+		m(n) = d(2);
+		n = n + 1;
+		str = fgets(fh);
+	end
+
+	% Strip possible linefeed from description end
+	if double(desc(end)) == 10
+		desc = desc(1:end-1);
+	end
+	fprintf('Calibration Info : %s\n', desc);
+	i1 = strfind(desc, 'Sens Factor =');
+	i2 = strfind(desc, 'dB');
+	if length(i1) == 1 && length(i2) == 1
+		sens = sscanf(desc(i1+13:i2-1), '%f');
+		fprintf('Calibration Sens : %6.2f dB\n', sens);
+	end
+
+	fprintf('Calibration range: %.2f .. %.2f Hz\n', min(f), max(f));
+	fprintf('Calibration range: %.2f .. %.2f dB\n', min(m), max(m));
+
+	figure;
+	semilogx(f, m);
+	grid on;
+	title(desc);
+	xlabel('Frequency (Hz)');
+	ylabel('Magnitude (dB)');
 end
 
 function [x, seed] = mlsp12(seed, n)
@@ -304,3 +383,30 @@ function [x, seed] = mlsp12(seed, n)
 		end
 	end
 end
+
+%% Calibration apply function
+%  Resample microphone calibration data into used grid and
+%  then subtract calibration response from measured
+%  response.
+
+function [cal_f, cal_m_db] = apply_mic_calibration(f, m_db, rec)
+
+	if length(rec.cm) > 0
+		if ~isvector(rec.cm)
+			error('Calibration can be for one channel only');
+		end
+		mic_m_db = interp1(rec.cf, rec.cm, f, 'linear');
+		nans = isnan(mic_m_db);
+		idx = find(nans == 0);
+		cal_f = f(idx);
+		cal_db = mic_m_db(idx);
+		s = size(m_db);
+		for i = 1:s(2)
+			cal_m_db(:,i) = m_db(idx,i) - cal_db(:);
+		end
+	else
+		cal_m_db = m_db;
+		cal_f = f;
+	end
+
+end

tune/eq/mls_rec_config.txt

@@ -1,5 +1,16 @@
-rec.ssh = 0;         % Set to 1 for remote capture
-rec.user = '';       % Set to user@domain for ssh
-rec.dir = '/tmp';    % Directory for temporary files
-rec.dev = 'hw:0,0';  % Audio capture device
-rec.nch = 2;         % Number audio capture channels to use
+%% Recording device configuration
+
+rec.ssh = 0;             % Set to 1 for remote capture
+rec.user = '';           % Set to user@domain for ssh
+rec.dir = '/tmp';        % Directory for temporary files
+rec.dev = 'hw:0,0';      % Audio capture device
+rec.nch = 2;             % Number audio capture channels to use
+
+% Use '' if calibration is not needed. Otherwise set to
+% e.g. '1234567.txt'. Such calibration data format is supported for
+% some reasonably priced measurement microphones. The ASCII text
+% calibration data file is the measured frequency response of the used
+% microphone. Lines in the beginning those start with character " are
+% treated as comment. The successive lines should be <frequency>
+% <magnitude> number pairs. Their unit must be Hz and dB.
+rec.cal = '';