def adjust_seconds_fr(samples_per_channel_in_frame,fs,seconds_fr,num_frame):
    """
    Get the timestamp for the first sample in this frame.
    
    Parameters
    ----------
     samples_per_channel_in_frame : int
         number of sample components per channel.
     fs : int or float
         sampling frequency.
     seconds_fr : int or float
         seconds for this frame (from frame header)
     num_frame : int
         frame number (from frame header).
     
    Returns
    -------
     time_first_frame : float
         timestamp [s] corresponding to the first sample of this frame.
    """
    seconds_per_frame=samples_per_channel_in_frame/float(fs)
    time_first_sample=float(seconds_fr)+num_frame*seconds_per_frame
    return(time_first_sample)