Create smandrap_Apply x db to send y on selected tracks.lua

Various/smandrap_Apply x db to send y on selected tracks.lua

@@ -0,0 +1,54 @@
+-- @description Apply x db to send y on selected tracks
+-- @author smandrap
+-- @version 1.0
+-- @donation https://paypal.me/smandrap
+-- @about
+--  Bassman002 request. https://forum.cockos.com/showthread.php?p=2718351#post2718351
+--  
+--  Db to value (and viceversa) functions are taken from the forums. Can't remember where sorry.
+--  If someone can point it out, i will give credit.
+--
+--  Usage: 
+--    Duplicate the script and change DB_AMOUNT and SEND_IDX to taste.
+--
+--  Known issues:
+--    Undo doesn't work correctly
+
+---------------------
+
+-- CHANGE THESE:
+
+local DB_AMOUNT = -1
+local SEND_IDX = 1      -- Target send, 1 based
+
+
+---------------------
+
+
+local LN10_OVER_TWENTY = 0.11512925464970228420089957273422
+local TWENTY_OVER_LN10 = 8.6858896380650365530225783783321
+local MINUS_INFINITY_TRESHOLD = 0.0000000298023223876953125
+
+local function DbToValue(db) return math.exp(db * LN10_OVER_TWENTY) end
+
+local function ValueToDb(value) 
+  if value < MINUS_INFINITY_TRESHOLD then return -150 end
+  return math.max(-150, math.log(value) * TWENTY_OVER_LN10)
+end
+
+local function main()
+  local sel_tr_cnt = reaper.CountSelectedTracks()
+  if sel_tr_cnt == 0 then return end
+
+  for i = 0, sel_tr_cnt - 1 do
+    local tr = reaper.GetSelectedTrack(0, i)
+    local send_vol = reaper.GetTrackSendInfo_Value(tr, 0, SEND_IDX - 1, 'D_VOL')
+    local new_vol = DbToValue(ValueToDb(send_vol) + DB_AMOUNT)
+
+    reaper.SetTrackSendInfo_Value(tr, 0, SEND_IDX - 1, 'D_VOL', new_vol)
+  end
+end
+
+reaper.Undo_BeginBlock()
+main()
+reaper.Undo_EndBlock("Apply "..DB_AMOUNT.." db to Send "..SEND_IDX.." on selected tracks", -1)