From f5122511f299fa81e1ac4229edbcf366964f2b5a Mon Sep 17 00:00:00 2001
From: inference <admin@inferencium.net>
Date: Sun, 6 Nov 2022 09:08:53 +0000
Subject: [PATCH] Add MPV equalizer script.

---
 mpv/scripts/equalizer.lua | 250 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 250 insertions(+)
 create mode 100644 mpv/scripts/equalizer.lua

diff --git a/mpv/scripts/equalizer.lua b/mpv/scripts/equalizer.lua
new file mode 100644
index 0000000..6448394
--- /dev/null
+++ b/mpv/scripts/equalizer.lua
@@ -0,0 +1,250 @@
+--[[
+mpv 5-bands equalizer with visual feedback.
+Copyright 2016 Avi Halachmi ( https://github.com/avih )
+License: public domain
+Default config:
+- Enter/exit equilizer keys mode: ctrl+e
+- Equalizer keys: 2/w control bass ... 6/y control treble, and middles in between
+- Toggle equalizer without changing its values: ctrl+E (ctrl+shift+e)
+- Reset equalizer values: alt+ctrl+e
+- See ffmpeg filter description below the config section
+--]]
+-- ------ config -------
+local start_keys_enabled = false  -- if true then choose the up/down keys wisely
+local key_toggle_bindings = 'ctrl+e'  -- enable/disable equalizer key bindings
+local key_toggle_equalizer = 'ctrl+E'  -- enable/disable equalizer
+local key_reset_equalizer = 'alt+ctrl+e'  -- sets all bands to gain 0
+
+-- reduce clicks (update the filter chain inplace). requires ffmpeg >= 4.0
+local inplace = true
+
+-- configure the equalizer keys, bands, and initial gain value for each band
+local bands = {
+  -- octave is x2. e.g. two octaves range around f is from f/2 to f*2
+  --      {up  down}
+  {keys = {'2', 'w'}, filter = {'equalizer=f=64:width_type=o:w=3.3:g=', 0}}, -- 20-200
+  {keys = {'3', 'e'}, filter = {'equalizer=f=400:width_type=o:w=2.0:g=', 0}}, -- 200-800
+  {keys = {'4', 'r'}, filter = {'equalizer=f=1250:width_type=o:w=1.3:g=', 0}}, -- 800-2k
+  {keys = {'5', 't'}, filter = {'equalizer=f=2830:width_type=o:w=1.0:g=', 0}}, -- 2k-4k
+  {keys = {'6', 'y'}, filter = {'equalizer=f=5600:width_type=o:w=1.0:g=', 0}}, -- 4k-8k
+--{keys = {'7', 'u'}, filter = {'equalizer=f=12500:width_type=o:w=1.3:g=', 0}} -- - 20k
+}
+
+--[[
+https://ffmpeg.org/ffmpeg-filters.html#equalizer
+Apply a two-pole peaking equalisation (EQ) filter. With this filter, the signal-level
+at and around a selected frequency can be increased or decreased, whilst (unlike
+bandpass and bandreject filters) that at all other frequencies is unchanged.
+In order to produce complex equalisation curves, this filter can be given several
+times, each with a different central frequency.
+The filter accepts the following options:
+frequency, f: Set the filter’s central frequency in Hz.
+width_type: Set method to specify band-width of filter.
+    h  Hz
+    q  Q-Factor 
+    o  octave 
+    s  slope 
+width, w: Specify the band-width of a filter in width_type units.
+gain, g:  Set the required gain or attenuation in dB. Beware of clipping when
+          using a positive gain. 
+--]]
+
+
+-- ------- utils --------
+function iff(cc, a, b) if cc then return a else return b end end
+function ss(s, from, to) return s:sub(from, to - 1) end
+--[[-- utils
+local mp_msg   = require 'mp.msg'
+function midwidth(min, max)  -- range --> middle freq and width in octaves
+  local wo = math.log(max / min) / math.log(2)
+  mp_msg.info(min, max / (2 ^ (wo / 2)) .. ' <' .. wo .. '>', max)
+end
+function range(f, wo)  -- middle freq and width in octaves --> range
+  local h = 2 ^ (wo / 2)
+  mp_msg.info(f / h, '' .. f .. ' <' .. wo .. '>' , f * h)
+end
+--]]
+
+-- return the filter as numbers {frequency, gain}
+local function filter_data(filter)
+  return { tonumber(ss(filter[1], 13, filter[1]:find(':', 14, true))), filter[2] }
+end
+
+-- the mpv command string for adding the filter (only used when gain != 0)
+local function get_cmd(filter)
+  return 'no-osd af add lavfi=[' .. filter[1] .. filter[2] .. ']'
+end
+
+-- setup named filter equalizer<band>
+local function get_cmd_band_inplace_setup(filter, band, reset)
+  local v = reset and 0 or filter[2]
+  return 'no-osd af add @equalizer'.. band ..':lavfi=[' .. filter[1] .. v .. ']'
+end
+
+-- update gain of named filter equalizer<band> inplace
+local function get_cmd_band_inplace(filter, band, reset)
+  local v = reset and 0 or filter[2]
+  return 'no-osd af-command equalizer'.. band ..' g '.. v
+end
+
+-- these two vars are used globally
+local bindings_enabled = start_keys_enabled
+local eq_enabled = true  -- but af is not touched before the equalizer is modified
+
+local inplace_init = false
+
+
+-- ------ OSD handling -------
+local function ass(x)
+  -- local gpo = mp.get_property_osd
+  -- return gpo('osd-ass-cc/0') .. x .. gpo('osd-ass-cc/1')
+
+  -- seemingly it's impossible to enable ass escaping with mp.set_osd_ass,
+  -- so we're already in ass mode, and no need to unescape first.
+  return x
+end
+
+local function fsize(s)  -- 100 is the normal font size
+  return ass('{\\fscx' .. s .. '\\fscy' .. s ..'}')
+end
+
+local function color(c)  -- c is RRGGBB
+  return ass('{\\1c&H' .. ss(c, 5, 7) .. ss(c, 3, 5) .. ss(c, 1, 3) .. '&}')
+end
+
+local function cnorm() return color('ffffff') end  -- white
+local function cdis()  return color('909090') end  -- grey
+local function ceq()   return iff(eq_enabled, color('ffff90'), cdis()) end  -- yellow-ish
+local function ckeys() return iff(bindings_enabled, color('90FF90'), cdis()) end  -- green-ish
+
+local DUR_DEFAULT = 1.5 -- seconds
+local osd_timer = nil
+-- duration: seconds, or default if missing/nil, or infinite if 0 (or negative)
+local function ass_osd(msg, duration)  -- empty or missing msg -> just clears the OSD
+  duration = duration or DUR_DEFAULT
+  if not msg or msg == '' then
+    msg = '{}'  -- the API ignores empty string, but '{}' works to clean it up
+    duration = 0
+  end
+  mp.set_osd_ass(0, 0, msg)
+  if osd_timer then
+    osd_timer:kill()
+    osd_timer = nil
+  end
+  if duration > 0 then
+    osd_timer = mp.add_timeout(duration, ass_osd)  -- ass_osd() clears without a timer
+  end
+end
+
+-- some visual messing about
+local function updateOSD()
+  local msg1 = fsize(70) .. 'Equalizer: ' .. ceq() .. iff(eq_enabled, 'On', 'Off')
+            .. ' [' .. key_toggle_equalizer .. ']' .. cnorm()
+  local msg2 = fsize(70)
+            .. 'Key-bindings: ' .. ckeys() .. iff(bindings_enabled, 'On', 'Off')
+            .. ' [' .. key_toggle_bindings .. ']' .. cnorm()
+  local msg3 = ''
+
+  for i = 1, #bands do
+    local data = filter_data(bands[i].filter)
+    local info =
+      ceq() .. fsize(50) .. data[1] .. ' hz ' .. fsize(100)
+      .. iff(data[2] ~= 0 and eq_enabled, '', cdis()) .. data[2] .. ceq()
+      .. fsize(50) .. ckeys() .. ' [' .. bands[i].keys[1] .. '/' .. bands[i].keys[2] .. ']'
+      .. ceq() .. fsize(100) .. cnorm()
+
+    msg3 = msg3 .. iff(i > 1, '   ', '') .. info
+  end
+
+  local nlb = '\n' .. ass('{\\an1}')  -- new line and "align bottom for next"
+  local msg = ass('{\\an1}') .. msg3 .. nlb .. msg2 .. nlb .. msg1
+  local duration = iff(start_keys_enabled, iff(bindings_enabled and eq_enabled, 5, nil)
+                                         , iff(bindings_enabled, 0, nil))
+  ass_osd(msg, duration)
+end
+
+
+-- ------- actual functionality ------
+local function updateAF_simple()  -- setup an audio filter chain which applies the equalizer
+  mp.command('no-osd af clr ""')  -- af clr must have two double-quotes
+  if not eq_enabled then return end
+
+  for i = 1, #bands do
+    local f = bands[i].filter
+    if f[2] ~= 0 then  -- insert filters only were the gain is non default
+      mp.command(get_cmd(f))
+    end
+  end
+end
+
+-- update gains of the whole equalizer inplace, also setup on first time
+local function updateAF_inplace()
+  for i = 1, #bands do
+    local f = bands[i].filter
+    if not inplace_init then
+      mp.command(get_cmd_band_inplace_setup(f, i, not eq_enabled))
+    end
+    mp.command(get_cmd_band_inplace(f, i, not eq_enabled))
+  end
+  inplace_init = true
+end
+
+if inplace then
+    updateAF = updateAF_inplace
+else
+    updateAF = updateAF_simple
+end
+
+local function getBind(filter, delta)
+  return function()  -- onKey
+    filter[2] = filter[2] + delta
+    updateAF()
+    updateOSD()
+  end
+end
+
+local function update_key_binding(enable, key, name, fn)
+  if enable then
+    mp.add_forced_key_binding(key, name, fn, 'repeatable')
+  else
+    mp.remove_key_binding(name)
+  end
+end
+
+local function toggle_bindings(explicit, no_osd)
+  bindings_enabled = iff(explicit ~= nil, explicit, not bindings_enabled)
+  for i = 1, #bands do
+    local k = bands[i].keys
+    local f = bands[i].filter
+    update_key_binding(bindings_enabled, k[1], 'eq' .. k[1], getBind(f,  1)) -- up
+    update_key_binding(bindings_enabled, k[2], 'eq' .. k[2], getBind(f, -1)) -- down
+  end
+  if not no_osd then updateOSD() end
+end
+
+local function toggle_equalizer()
+  eq_enabled = not eq_enabled
+  updateAF()
+  updateOSD()
+end
+
+local function reset_equalizer()
+  for i = 1, #bands do
+    bands[i].filter[2] = 0
+  end
+  updateAF()
+  updateOSD()
+end
+
+mp.add_forced_key_binding(key_toggle_equalizer, toggle_equalizer)
+mp.add_forced_key_binding(key_toggle_bindings, toggle_bindings)
+mp.add_forced_key_binding(key_reset_equalizer, reset_equalizer)
+if bindings_enabled then toggle_bindings(true, true) end
+
+-- init: setup the equalizer if the initial gain is not 0
+for i = 1, #bands do
+    if bands[i].filter[2] ~= 0 then
+        updateAF()
+        break
+    end
+end