soft/test/audio/test_utils/find_test_signal.m

function [d, nt, nt_use, nt_skip] = find_test_signal(x, test)

%%
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% Author: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>
%

%% Find start marker
fprintf('Finding test start marker...\n');
s = sync_chirp(test.fs, 'up');
nx = length(x);
n_seek = round(test.fs*(test.idle_t + test.mark_t));
n = min(round(test.fs*test.sm), n_seek);
y = x(1:n);
[r, lags] = xcorr(y, s);
[r_max, idx] = max(r);
d_start = lags(idx);

%% Find end marker
fprintf('Finding test end marker...\n');
s = sync_chirp(test.fs, 'down');
n_seek = round(test.fs*(2*test.idle_t + test.mark_t));
n = min(round(test.fs*test.em),n_seek);
y = x(end-n+1:end);
[r, lags] = xcorr(y, s);
[r_max, idx] = max(r);
d_end = nx-n+lags(idx);

%% Check correct length of signal
len = d_end-d_start;
len_s = len/test.fs;
ref_s = test.mark_t+test.nf*test.na*test.tl;
if abs(len_s-ref_s) > test.mt
        len_s
        ref_s
        error('Start and end markers were not found. Test play or capture quality may be poor');
end

%% Delay to first tone, length of tone in samples
d = d_start + round(test.mark_t*test.fs);
if (d < 0)
	error('Invalid negative delay seen. Test play or capture quality may be poor');
end
nt = round(test.tl*test.fs);
nt_use = nt -round(test.is*test.fs) -round(test.ie*test.fs);
if nt_use < 0
        error('Test signal length parameters must be wrong!');
end
nt_skip = round(test.is*test.fs);

end