Tools: Add more robustness to check_volume_levels.m measure

This patch delays the check window if the gain settling seems
to be still happening in the beginning of level check window.
The settling is detected with differential of gain.

The delay in gain settling can be caused by random alsamixer
controls apply delay. Also a long gain ramp makes the settling
to appear later.

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

Author: singalsu

tools/check_volume_levels.m

@@ -187,15 +187,28 @@ function plot_levels(meas, tc, lm)
 
 function pass = check_levels(meas, tc, lm, verbose)
 	pass = 1;
+	dg_tol = 0.1;
 	gains =  meas.levels - lm.sine_dbfs;
 	sv = size(tc.volumes);
 	for j = 1:sv(2)
 		for i = 1:sv(1)
+			% Initial location to test
 			ts = tc.vctimes(i)+tc.meas(1);
 			te = tc.vctimes(i)+tc.meas(2);
 			idx0 = find(meas.t < te);
 			idx = find(meas.t(idx0) > ts);
-			avg_gain = mean(gains(idx, j));
+
+			% Delay if settled gain is later in the window,
+			% this adds more robustness to test for controls
+			% apply delay.
+			dg = diff(gains(idx,j));
+			if max(abs(dg)) > dg_tol
+				dg_rev = dg(end:-1:1);
+				idx_add = length(dg) - find(abs(dg_rev) > 0.1, 1, 'first') + 1;
+			else
+				idx_add = 0;
+			end
+			avg_gain = mean(gains(idx + idx_add, j));
 			max_gain = tc.volumes(i,j) + tc.vtol;
 			min_gain = tc.volumes(i,j) - tc.vtol;
 			if avg_gain > max_gain