dicklyon@608: function layer_struct = SAI_StabilizeLayer(layer_struct)
dicklyon@608: % Pick trigger points in buffer, shift rows to offset_from_end,
dicklyon@608: % and blend into frame
dicklyon@608: 
dicklyon@608: frame = layer_struct.frame;
dicklyon@608: 
dicklyon@608: nap_buffer = real(layer_struct.nap_buffer);
dicklyon@608: n_buffer_times = size(nap_buffer, 1);
dicklyon@608: [n_ch, width] = size(frame);
dicklyon@608: 
dicklyon@608: % Make the window to use for all the channels at this layer.
dicklyon@608: window_size = layer_struct.window_width;
dicklyon@608: n_window_pos = layer_struct.n_window_pos;
dicklyon@608: % Windows are always (approx) 50% overlapped:
dicklyon@608: d_win = window_size / 2;
dicklyon@608: 
dicklyon@608: after_samples = layer_struct.future_lags;
dicklyon@608: 
dicklyon@608: window_range = (1:window_size) + ...
dicklyon@608:   (n_buffer_times - window_size) - after_samples - ...
dicklyon@608:   floor((n_window_pos - 1) * d_win);
dicklyon@608: window = sin((1:window_size)' * pi / window_size);
dicklyon@608: % This should not go negative!
dicklyon@608: offset_range = (1:width) + ...
dicklyon@608:   (n_buffer_times - width - window_size) - floor((n_window_pos - 1) * d_win);
dicklyon@608: % CHECK
dicklyon@608: if any(offset_range < 0)
dicklyon@608:   error;
dicklyon@608: end
dicklyon@608: 
dicklyon@608: % smooth across channels; more in later layers
dicklyon@608: smoothed_buffer =  smooth1d(nap_buffer', layer_struct.channel_smoothing_scale)';
dicklyon@608: 
dicklyon@608: % For each buffer column (channel), pick a trigger and align into SAI_frame
dicklyon@608: for ch = 1:n_ch
dicklyon@608:   smooth_wave = smoothed_buffer(:, ch);  % for the trigger
dicklyon@608:   
dicklyon@608:   % Do several window positions and triggers
dicklyon@608:   for w = 1:n_window_pos
dicklyon@608:     % move the window to later and go aggain
dicklyon@608:     [peak_val, trigger_time] = max(smooth_wave(window_range + ...
dicklyon@608:       floor((w - 1) * d_win)) .* window);
dicklyon@608:     nap_wave = nap_buffer(:, ch);  % for the waveform
dicklyon@608:     if peak_val <= 0  % just use window center instead
dicklyon@608:       [peak_val, trigger_time] = max(window);
dicklyon@608:     end
dicklyon@608:     % TODO(dicklyon):  alpha blend here.
dicklyon@608:     trigger_time = trigger_time + floor((w - 1) * d_win);
dicklyon@608:     alpha = (0.025 + peak_val) / (0.5 + peak_val);  % alpha 0.05 to near 1.0
dicklyon@608:     frame(ch, :) = alpha * nap_wave(trigger_time + offset_range)' + ...
dicklyon@608:       (1 - alpha) * frame(ch, :);
dicklyon@608:   end
dicklyon@608: end
dicklyon@608: 
dicklyon@608: layer_struct.frame = frame;