FCEUX LUA script to automate capture of unique NES ROMs screenshots

run.sh

#!/bin/sh

rm ~/.fceux/fceux.cfg
for i in *.nes; do
  fceux --loadlua screenshot.lua "$i"
  mv screen.01.png "$i".png
  rm screen.??.png 2>/dev/null
done

screenshot.lua

--
-- Lua script for FCEUX for capturing a screenshot
--
-- Generates screenshots for a ROM. Output is "screen.01.png" for each.  Change
-- the call to ss() at the bottom to change number of unique screenshots to
-- capture etc.
--

-- Usage:
--
-- apt install -y fceux
-- fceux --loadlua screenshot.lua any_rom.nes
--

function md5 (file)
  local fh = io.popen(string.format("md5sum '%s'", string.gsub(file, "'", [['\'']])))
  local res = fh:read("*a")
  fh:close()
  return string.gsub(res, '%s.+', '');
end

function contains (arr, val)
  local v = ''; 
  local i = 0;
  for i,v in ipairs(arr) do
    if ( val == v ) then
      return true
    end 
  end 
  return false
end

function ss (num_to_save, interval, max_frames)
  local ss_num = 1;
  local last_ss_frame = 0;
  local md5s = { '306d572ee2b10e99d608f67fad5cf1fd' }; -- start with all black
  while ( ss_num <= num_to_save and emu.framecount() <= max_frames ) do
    local i = emu.framecount();
    emu.frameadvance();
    if ( i >= last_ss_frame + interval ) then
      local ss_name = string.format("%s.%02d.png", "screen", ss_num);
      emu.print(string.format("Saving screenshot: %s (at frame %d)", ss_name, i));
      gui.savescreenshotas(ss_name);
      last_ss_frame = i;
      emu.frameadvance();
      emu.pause();
      local cur_md5 = md5(ss_name);
      if contains(md5s, cur_md5) then
        os.execute(string.format("rm '%s'", string.gsub(ss_name, "'", [['\'']])));
      else
        table.insert(md5s, cur_md5);
        ss_num = ss_num + 1;
      end 
      emu.unpause();
    end 
  end 
end

emu.print("Init...")
-- about 60 fps
-- ss(num_unquie_screens, frames_between_shots, max_frames)
ss(5, 21, 15*60)
os.exit()