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Compute effective sampling rate even when nominal rate is 0 + better handle empty streams. #14

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Compute effective sampling rate even when nominal rate is 0 + better handle empty streams. #14

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7cfd075
Compute effective sampling rate even when nominal is 0
jfrey-xx Dec 1, 2017
e95ef68
Add a warning about effective srate when nominal is 0.
jfrey-xx Dec 1, 2017
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5 changes: 4 additions & 1 deletion Matlab/eeg_load_xdf.m
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,10 @@
% (default: 'EEG')
%
% 'effective_rate' : if true, use the effective sampling rate instead of the nominal
% sampling rate (as declared by the device) (default: false)
% sampling rate (as declared by the device). Note that using
% effective_rate can lead to incorrect results if the nominal
% sampling rate is 0 (i.e. non constant sample interval)
% (default: false)
%
% 'exclude_markerstreams' : can be a cell array of stream names to exclude from
% use as marker streams (default: {})
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14 changes: 11 additions & 3 deletions Matlab/xdf/load_xdf.m
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Expand Up @@ -348,6 +348,7 @@
if temp(id).srate > 0
temp(id).sampling_interval = 1/temp(id).srate;
else
warning('Nominal sampling rate of stream %s is 0. Calculated effective sampling rate might not be meaningful, relying on this rate is not recommended.', header.info.name);
temp(id).sampling_interval = 0;
end
% fread parsing format for data values
Expand Down Expand Up @@ -552,18 +553,25 @@
end

% calculate the weighted mean sampling rate over all segments
temp(k).effective_rate = sum(bsxfun(@times,[segments.effective_srate],[segments.num_samples]/sum([segments.num_samples])));
temp(k).effective_srate = sum(bsxfun(@times,[segments.effective_srate],[segments.num_samples]/sum([segments.num_samples])));

% transfer the information into the output structs
streams{k}.info.effective_srate = temp(k).effective_rate;
streams{k}.info.effective_srate = temp(k).effective_srate;
streams{k}.segments = segments;
end
end
end
else
% calculate effective sampling rate
for k=1:length(temp)
temp(k).effective_srate = (length(temp(k).time_stamps) - 1) / (temp(k).time_stamps(end) - temp(k).time_stamps(1)); end
if length(temp(k).time_stamps) > 0
temp(k).effective_srate = (length(temp(k).time_stamps) - 1) / (temp(k).time_stamps(end) - temp(k).time_stamps(1));
else
temp(k).effective_srate = 0;
end
% transfer the information into the output structs
streams{k}.info.effective_srate = temp(k).effective_srate;
end
end

% copy the information into the output
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