ReaScript Lua Tutorial

ReaScriptLesson03-VolumeConversion.lua

---------------- Old Version :
vol_dB = 20 * ( math.log( vol_log, 10 ) )
vol_log = math.exp( vol_dB * 0.115129254 )


---------------- New Version :

-- Mod from SPK77
-- http://forum.cockos.com/showpost.php?p=1608719&postcount=6

function dBFromVal(val) return 20*math.log(val, 10) end
function ValFromdB(dB_val) return 10^(dB_val/20) end

-- test
some_dB_val = dBFromValue(2) -- should be ~6.02 dB
some_dB_val_to_val = ValFromdB(some_dB_val) -- should be "2"

ReaScriptLesson04-LoopInSelectedItems.lua

selected_items_count = reaper.CountSelectedMediaItems(0)

-- INITIALIZE loop through selected items
for i = 0, selected_items_count-1  do
	-- GET ITEMS
	item = reaper.GetSelectedMediaItem(0, i) -- Get selected item i
	
	-- DO SOMETHING HERE
	
end -- ENDLOOP through selected items

ReaScriptLesson05-ConditionsBasics.lua

function Msg(param)
  reaper.ShowConsoleMsg(tostring(param).."\n")
end

function Main()
  
  item_mouse, mouse_pos  = reaper.BR_ItemAtMouseCursor() -- Get item under mouse
  
  if item_mouse ~= nil then -- If no item under mouse
      
      -- INSERT CODE HERE
  
  end -- ENDIF no item under mouse
  
end

reaper.ShowConsoleMsg("")
Main()

ReaScriptLesson07-LoopOnSelectedItemsOnTracks.lua

function Msg(param)
  reaper.ShowConsoleMsg(tostring(param).."\n")
end

function Main()
    
    reaper.Main_OnCommand(40289, 0)
    
    item_mouse, mouse_pos  = reaper.BR_ItemAtMouseCursor()
    
    if tostring(item_mouse) ~= "userdata: 0000000000000000" then
    
        item_mouse_fadeout = reaper.GetMediaItemInfo_Value(item_mouse, "D_FADEOUTLEN")
        
        start_time, end_time = reaper.GetSet_LoopTimeRange2(0, false, false, 0, 0, false)
        
        if start_time ~= end_time then
            
            Action()
        
        end
    
    end
    
end

function Action()
    
    count_sel_tracks = reaper.CountSelectedTracks(0)
    
    for j = 0, count_sel_tracks - 1 do
    
        track = reaper.GetSelectedTrack(0, j)
        
        count_items_on_track = reaper.CountTrackMediaItems(track)
        
        for i = 0, count_items_on_track - 1 do
            
            item = reaper.GetTrackMediaItem(track, i)
            
            item_pos = reaper.GetMediaItemInfo_Value(item, "D_POSITION")
            
            if item_pos > end_time then
            
                break
            
            else
            
                item_len = reaper.GetMediaItemInfo_Value(item, "D_LENGTH")
                item_end = item_pos + item_len
                
                if (item_pos > start_time and item_pos < end_time) or (item_end > start_time and item_end < end_time) or (item_pos < start_time and item_end > end_time) then
                    
                        
                    reaper.SetMediaItemInfo_Value(item, "D_FADEOUTLEN", item_mouse_fadeout)
                
                end
                
            end
            
        end
    
    end
    
    reaper.UpdateArrange()

end

reaper.ShowConsoleMsg("")
Main()

ReaScriptLesson08-UsingNativeActions.lua

-- RUN A NATIVE ACTION
-- Base on it's command ID.
reaper.Main_OnCommand(40289, 0) -- Unselect all items

-- RUN AN ACTION FROM A EXTENSION, LIKE SWS
-- You will need another function to do that.
reaper.Main_OnCommand(reaper.NamedCommandLookup("_SWS_SELTRKWITEM"), 0) -- Select only track with selected items

ReaScriptLesson09-PreventingBugs.lua

-- A function to set an Item Fade-Out Length in security.
function SetItemFadeOut(item, item_len, fade_out_len)

	fade_in_len = reaper.GetMediaItemInfo_Value(item, "D_FADEINLEN")
	
	max_value = item_len - fade_in_len
	
	if fade_out_len > max_value then
		fade_out_len = max_value
	end
	
	--[[ Optionnal
	if fade_out_len < 0
		fade_out_len = 0
	end
	]]

	reaper.SetMediaItemInfo_Value(item, "D_FADEOUTLEN", fade_out_len)

end