view matlab/bmm/carfac/SAI_StabilizeLayer.m @ 648:1c2a5868f23a

Fix memory leak in CARFAC.

Also get rid of most uses of auto, which tend to hurt readability
unless the type name is particularly long, especially when it masks
pointers.

function layer_struct = SAI_StabilizeLayer(layer_struct)
% Pick trigger points in buffer, shift rows to offset_from_end,
% and blend into frame

frame = layer_struct.frame;

nap_buffer = real(layer_struct.nap_buffer);
n_buffer_times = size(nap_buffer, 1);
[n_ch, width] = size(frame);

% Make the window to use for all the channels at this layer.
window_width = layer_struct.window_width;
n_window_pos = layer_struct.n_window_pos;
% Windows are always (approx) 50% overlapped:
window_hop = window_width / 2;

window = sin((1:window_width)' * pi / window_width);
window_start = (n_buffer_times - window_width) - ...
    floor((n_window_pos - 1) * window_hop);
window_range = (1:window_width) + window_start - layer_struct.future_lags;
% This should not go negative!
offset_range = (1:width) + window_start - width;
% CHECK
if any(offset_range < 0)
  error;
end

% smooth across channels; more in later layers
smoothed_buffer =  smooth1d(nap_buffer', layer_struct.channel_smoothing_scale)';

% For each buffer column (channel), pick a trigger and align into SAI_frame
for ch = 1:n_ch
  smooth_wave = smoothed_buffer(:, ch);  % for the trigger
  
  % Do several window positions and triggers
  for w = 1:n_window_pos
    % move the window to later and go again
    current_window_offset = floor((w - 1) * window_hop);
    [peak_val, trigger_time] = ...
        max(smooth_wave(window_range + current_window_offset) .* window);
    nap_wave = nap_buffer(:, ch);  % for the waveform
    if peak_val <= 0  % just use window center instead
      [peak_val, trigger_time] = max(window);
    end
    trigger_time = trigger_time + current_window_offset;
    alpha = (0.025 + peak_val) / (0.5 + peak_val);  % alpha 0.05 to near 1.0
    frame(ch, :) = alpha * nap_wave(trigger_time + offset_range)' + ...
      (1 - alpha) * frame(ch, :);
  end
end

layer_struct.frame = frame;