Move to next pitch position in first selected items

gistfile1.lua

reaper.PreventUIRefresh(1)

console = true
threshold = 0.01 -- arbitrary

reaper.ClearConsole()

function Msg(val)
  if console then
    reaper.ShowConsoleMsg(tostring(val).."\n")
  end
end

function GetSourceItemFrequencyAtPosition2( take, pos, nch, ns, buf )
  local rv = reaper.GetMediaItemTake_Peaks(take,1000.0,pos,nch,ns,115,buf)
  if rv & (1<<24) and (rv&0xfffff) > 0 then
    local spl = buf[nch*ns*2 + 1]
    local freq = tonumber(string.format("%d",spl&0x7fff))
    local tonal = tonumber(string.format("%f",(spl>>15)/16384.0))
    return freq, tonal
   end 
end

local reaper = reaper

item = reaper.GetSelectedMediaItem(0,0)

if item then
  
  take = reaper.GetActiveTake(item,0)
  
  if take and not reaper.TakeIsMIDI(take) then
    
    pos = reaper.GetCursorPosition()
    itemstart = reaper.GetMediaItemInfo_Value(item, "D_POSITION")
    itemend = itemstart + (reaper.GetMediaItemInfo_Value(item, "D_LENGTH"))
    
    if itemstart <= pos and pos < itemend then
      source = reaper.GetMediaItemTake_Source(take)
      nch = reaper.GetMediaSourceNumChannels(source)
      ns = 1
      buf = reaper.new_array(ns*3*nch)
      
      startfreq = GetSourceItemFrequencyAtPosition2( take, pos, nch, ns, buf )
     
      semup = startfreq*1.05946309436 -- up a semitone
      semdown = startfreq*0.94387431268 -- down a semitone
      
      Msg("Source")
      Msg(startfreq)
      Msg("Target")
     
      while pos < itemend do
        pos = pos + threshold
        newfreq, tonali = GetSourceItemFrequencyAtPosition2( take, pos, nch, ns, buf )
        
        Msg(newfreq)
        
        if (newfreq >= semup or newfreq <= semdown) and (tonali > 0.8) then
         reaper.SetEditCurPos(pos, 1, 0)
         break
        end
        
        if pos >= itemend then break end
      
      end
    
    end
  
  end
end 

reaper.PreventUIRefresh(-1)