Auto Piano and Piano scanner

--[[
    Auto Piano Scanner v4
    - "A" button (right side)  -> show / hide the music panel
    - Scanner box keeps scanning + playing even while the panel is hidden
    - "BOX" button in the header -> show / hide the scanner box visuals only
    - Small red stop button appears next to "A" while a song is playing
    - Play presses the detected keys using TOUCH input
]]

local Players = game:GetService("Players")
local UIS = game:GetService("UserInputService")
local GuiService = game:GetService("GuiService")
local HttpService = game:GetService("HttpService")
local TweenService = game:GetService("TweenService")
local VIM = game:GetService("VirtualInputManager")

local lp = Players.LocalPlayer
local playerGui = lp:WaitForChild("PlayerGui")
local httpRequest = request or http_request or (syn and syn.request) or (http and http.request)

-- remove the previous instance if the script is executed again
pcall(function()
    if getgenv and getgenv().AutoPianoGui then
        getgenv().AutoPianoGui:Destroy()
    end
end)

---------------------------------------------------------------------
-- MIDI parser -> list of {time = seconds, n = note number}
---------------------------------------------------------------------
local function parseMidi(s)
    assert(s:sub(1, 4) == "MThd", "not a MIDI file")
    local hlen = string.unpack(">I4", s, 5)
    local _, _, division = string.unpack(">I2I2I2", s, 9)
    local pos = 9 + hlen
    local notes, tempos = {}, {}

    local function vlq()
        local v = 0
        repeat