function [actual_frames, actual_seconds, nominal_frames, nominal_seconds] = MoBI_frames_Brescia(secs, ifi)


% first output = number of frames output shortened by a 0.5 frames to be inserted into
% the (Screen('Flip'), VBL) as waiting. This strategy allows to have
% exactly the delay that is the closest one to the delay requested

% second output = actual seconds to wait for the next flip to happen


% example: the set delay is 0.21 secs, with a inter frame interval of
% 0.0167 s (60 Hz refresh rate)
% 0.21 s is not a multiple of the frame interval
% so 0.21 is going to be rounded to the closer multple --> 13 frames (which corresponds to 0.2171s)
% in order to avoid that Psuchtoolbox flips randomly at 13 or at 14 frames
% the strategy is to reduce the delay to be inserted in the function by a
% half frame. --> 12.5
% then the function transforms back the 12.5 frames into seconds

% thus the flipping will happen always and exactly at (13 frames * ifi) which is 0.2171s


% [actual_frames actual_seconds, nominal_frames nominal_seconds] = MoBI_frames_Brescia(0.21, 0.0167)

% actual_frames = 12.5000
% actual_seconds = 0.2087
% nominal_frames = 13
% nominal_seconds = 0.2100



% rounds the indicated time to an exact number of frames
nominal_frames = round(secs/ifi);

% subtract half frames in order not to risk an overshoot (longer duration than required)
actual_frames =  nominal_frames - 0.5; 

% true waiting
actual_seconds = actual_frames*ifi;


nominal_seconds = secs;


end