Norns screen capture

record.lua

local Screencap = {}


-- requires apng assmebler built from source
-- available here: http://apngasm.sourceforge.net
function Screencap.record(fps, duration, output_path)
  local timer = 0
  local delay_s = 1/fps
  local frame_count = 0
  local tempDir = "frames"
  local tempName = "frame"
  local apngasm_path = "/home/we/apgnasm/apngasm"
  
  os.execute("mkdir /tmp/"..tempDir)

  clock.run(
    function()
      
      -- capture each frame
      while timer < duration do
        _norns.screen_export_png("/tmp/"..tempDir.."/"..tempName..string.format("%04d",frame_count)..".png")
        frame_count = frame_count + 1
        timer = timer + delay_s
        clock.sleep(delay_s)
      end
      
      -- assemble frames
      local s = "/tmp/"..tempDir.."/"..tempName.."*.png"
      os.execute(apngasm_path.. " " ..output_path.. " " ..s.. " 1 " ..fps)
      os.execute("rm -r /tmp/frames")
    end
  )
end

return Screencap