Ardour: Check for 0-length MIDI Notes on Save

0LenMIDIOnSave.lua

ardour {
  name        = "Check for 0-length MIDI Notes on Save",
  description = "Run on each SAVE, check for MIDI notes with length <= 0.001",
  author      = "Wolfram Esser, derwok",
  ["type"]    = "EditorHook"
}

-- HowTo:
-- Save to your OS's script path described here: https://manual.ardour.org/lua-scripting/
-- Then launch Ardour
-- Activate script via menu: Edit / Lua Script / Script Manager / Action Hooks
-- Click "New Hook" and select this script
-- Check will now run on current session on every Session save (signal: StateSaved)

function signals ()
  s = LuaSignal.Set()
  s:add ({[LuaSignal.StateSaved] = true})
  return s
end


function factory (params)
  return function (signal, ref, ...)
    MIN_LEN = 0.001  -- fractions of a beat 1/128 = 0.007
    zero_found = false

    if (signal == LuaSignal.StateSaved) then
      print ("")
      print ("You Saved! Checking for Zero-Length MIDI notes")
      for r in Session:get_tracks ():iter () do
          track_name = "Track: "..r:name()

          for p in Session:playlists():playlists_for_track (r:to_track()):iter() do
            playlist_name = p:name()
            if (p == r:to_track():playlist()) then
              playlist_name = "Active Playlist: " .. playlist_name
            else
              playlist_name = "In-Active Playlist: " .. playlist_name
            end

            for g in p:region_list (): iter() do
              local mr = g:to_midiregion ()
              if mr:isnil () then goto next end
              region_name = "MIDI Region: " .. g:name () .."  Pos:" .. g:position () .. "  Start:" .. g:start ()

              notes_errors = ""
              local nl = ARDOUR.LuaAPI.note_list (mr:model ())
              for n in nl:iter () do
                if n:length ():to_double() <= MIN_LEN then
                  local note_error = "Zero MIDI Note @beat:" .. n:time ():to_double() ..
                      "  " .. ARDOUR.ParameterDescriptor.midi_note_name (n:note ()) ..
                      "  Len:" .. n:length ():to_double()
                  notes_errors = notes_errors .. note_error .. "\n"
                  zero_found = true
                end
              end -- notelist

              if notes_errors ~= "" then
                print (track_name)
                print ("    ", playlist_name)
                print ("        ", region_name)
                print (notes_errors)
              end -- if

              ::next::
            end -- regions
          end -- playlists
      end  -- tracks

      if zero_found then 
        local md = LuaDialog.Message ("WARNING! Zero-Length MIDI Notes!", "There were zero-length MIDI notes!\nPlease click 'OK', then check Ardour's Error Log", 
                    LuaDialog.MessageType.Warning, LuaDialog.ButtonType.OK)
        md:run()
      else
        print ("** Check OK. No 0-length MIDI notes found.")
        print ("")
      end -- if 

    end -- signal == StateSaved
  end -- function
end -- factory