% see http://www.magiclantern.fm/forum/index.php?topic=16814.msg164062#msg164062
% check how Canon shutter values are rounded - in 1/8, or 1/3 & 1/2 EV increments?

f = fopen("SHUTTER.LOG", "r")

R = [];
S = [];

colors_normal  = {"b--.", "b--.", "b--o"};
colors_rounded = {"r--.", "r--.", "r--o"};

while 1,
    l = fgetl(f);
    if l == -1, break, end
    if length(l) > 5
        if strcmp(l(1:5), "1080p"),
            fps = str2num(l(6:7));
            raw = str2num(l(14:17));
            us  = str2num(l(83:88));
            %~ us = us + 5;
            R(end+1) = raw;
            S(end+1) = log2(1/(us/1e6));
        end
    else
        fps
        Rr = R;
        Rr(mod(R,8)~=4) = round(Rr(mod(R,8)~=4)/8*3)/3*8;
        stem(R,  (R-S*8-56)/8,  colors_normal{1}, 'linewidth', 0); hold on;
        stem(Rr, (Rr-S*8-56)/8, colors_rounded{1}, 'linewidth', 0);
        plot(R,  (R-S*8-56)/8,  'color', [0.7 0.7 1], 'markersize', 0);
        plot(Rr, (Rr-S*8-56)/8, 'color', [1 0.7 0.7], 'markersize', 0);
        colors_normal  = colors_normal(2:end);
        colors_rounded = colors_rounded(2:end);
        R = [];
        S = [];
    end
end
fclose(f)

a = axis;
h_normal = plot(0, 0, "b", 'markersize', 0);
h_rounded = plot(0, 0, "r", 'markersize', 0);
h_30p = plot(0, 0, "k--.");
h_25p = plot(0, 0, "k--o");
grid on
set(gca, 'xtick', [96:8:160])
axis(a);
legend([h_normal, h_rounded, h_25p, h_30p], {'raw shutter (1/8-stop increments)', 'rounded to 1/3 and 1/2-stop', "1080p 25 fps", "1080p 24/30 fps (identical)"});
xlabel('raw shutter')
ylabel('raw\_shutter / 8 - log2(1 / adtg\_shutter\_seconds) - 56 / 8 (EV)')
title('Shutter speed rounding test - 5D3 movie mode, raw shutter vs computed from ADTG')
print -dpng -FHelvetica:10 shutter.png