dicklyon@619: function layer_struct = SAI_StabilizeLayer(layer_struct)
dicklyon@619: % Pick trigger points in buffer, shift rows to offset_from_end,
dicklyon@619: % and blend into frame
dicklyon@619: 
dicklyon@619: frame = layer_struct.frame;
dicklyon@619: 
dicklyon@619: nap_buffer = real(layer_struct.nap_buffer);
dicklyon@619: n_buffer_times = size(nap_buffer, 1);
dicklyon@619: [n_ch, width] = size(frame);
dicklyon@619: 
dicklyon@619: % Make the window to use for all the channels at this layer.
ronw@675: window_width = layer_struct.window_width;
dicklyon@619: n_window_pos = layer_struct.n_window_pos;
dicklyon@619: % Windows are always (approx) 50% overlapped:
ronw@675: window_hop = window_width / 2;
dicklyon@619: 
ronw@675: window = sin((1:window_width)' * pi / window_width);
ronw@675: window_start = (n_buffer_times - window_width) - ...
ronw@675:     floor((n_window_pos - 1) * window_hop);
ronw@675: window_range = (1:window_width) + window_start - layer_struct.future_lags;
dicklyon@619: % This should not go negative!
ronw@675: offset_range = (1:width) + window_start - width;
dicklyon@619: % CHECK
dicklyon@619: if any(offset_range < 0)
dicklyon@619:   error;
dicklyon@619: end
dicklyon@619: 
dicklyon@619: % smooth across channels; more in later layers
dicklyon@619: smoothed_buffer =  smooth1d(nap_buffer', layer_struct.channel_smoothing_scale)';
dicklyon@619: 
dicklyon@619: % For each buffer column (channel), pick a trigger and align into SAI_frame
dicklyon@619: for ch = 1:n_ch
dicklyon@619:   smooth_wave = smoothed_buffer(:, ch);  % for the trigger
dicklyon@619:   
dicklyon@619:   % Do several window positions and triggers
dicklyon@619:   for w = 1:n_window_pos
ronw@675:     % move the window to later and go again
ronw@675:     current_window_offset = floor((w - 1) * window_hop);
ronw@675:     [peak_val, trigger_time] = ...
ronw@675:         max(smooth_wave(window_range + current_window_offset) .* window);
dicklyon@619:     nap_wave = nap_buffer(:, ch);  % for the waveform
dicklyon@619:     if peak_val <= 0  % just use window center instead
dicklyon@619:       [peak_val, trigger_time] = max(window);
dicklyon@619:     end
ronw@675:     trigger_time = trigger_time + current_window_offset;
dicklyon@619:     alpha = (0.025 + peak_val) / (0.5 + peak_val);  % alpha 0.05 to near 1.0
dicklyon@619:     frame(ch, :) = alpha * nap_wave(trigger_time + offset_range)' + ...
dicklyon@619:       (1 - alpha) * frame(ch, :);
dicklyon@619:   end
dicklyon@619: end
dicklyon@619: 
dicklyon@619: layer_struct.frame = frame;