1 files changed, 155 insertions, 0 deletions
diff --git a/TOOLS/lua/acompressor.lua b/TOOLS/lua/acompressor.lua
new file mode 100644
index 0000000..6a69140
--- /dev/null
+++ b/TOOLS/lua/acompressor.lua
@@ -0,0 +1,155 @@
+-- This script adds control to the dynamic range compression ffmpeg
+-- filter including key bindings for adjusting parameters.
+--
+-- See https://ffmpeg.org/ffmpeg-filters.html#acompressor for explanation
+-- of the parameters.
+
+local mp = require 'mp'
+local options = require 'mp.options'
+
+local o = {
+	default_enable = false,
+	show_osd = true,
+	osd_timeout = 4000,
+	filter_label = mp.get_script_name(),
+
+	key_toggle = 'n',
+	key_increase_threshold = 'F1',
+	key_decrease_threshold = 'Shift+F1',
+	key_increase_ratio = 'F2',
+	key_decrease_ratio = 'Shift+F2',
+	key_increase_knee = 'F3',
+	key_decrease_knee = 'Shift+F3',
+	key_increase_makeup = 'F4',
+	key_decrease_makeup = 'Shift+F4',
+	key_increase_attack = 'F5',
+	key_decrease_attack = 'Shift+F5',
+	key_increase_release = 'F6',
+	key_decrease_release = 'Shift+F6',
+
+	default_threshold = -25.0,
+	default_ratio = 3.0,
+	default_knee = 2.0,
+	default_makeup = 8.0,
+	default_attack = 20.0,
+	default_release = 250.0,
+
+	step_threshold = -2.5,
+	step_ratio = 1.0,
+	step_knee = 1.0,
+	step_makeup = 1.0,
+	step_attack = 10.0,
+	step_release = 10.0,
+}
+options.read_options(o)
+
+local params = {
+	{ name = 'attack',    min=0.01, max=2000, hide_default=true,  dB=''   },
+	{ name = 'release',   min=0.01, max=9000, hide_default=true,  dB=''   },
+	{ name = 'threshold', min= -30, max=   0, hide_default=false, dB='dB' },
+	{ name = 'ratio',     min=   1, max=  20, hide_default=false, dB=''   },
+	{ name = 'knee',      min=   1, max=  10, hide_default=true,  dB='dB' },
+	{ name = 'makeup',    min=   0, max=  24, hide_default=false, dB='dB' },
+}
+
+local function parse_value(value)
+	-- Using nil here because tonumber differs between lua 5.1 and 5.2 when parsing fractions in combination with explicit base argument set to 10.
+	-- And we can't omit it because gsub returns 2 values which would get unpacked and cause more problems. Gotta love scripting languages.
+	return tonumber(value:gsub('dB$', ''), nil)
+end
+
+local function format_value(value, dB)
+	return string.format('%g%s', value, dB)
+end
+
+local function show_osd(filter)
+	if not o.show_osd then
+		return
+	end
+
+	if not filter.enabled then
+		mp.commandv('show-text', 'Dynamic range compressor: disabled', o.osd_timeout)
+		return
+	end
+
+	local pretty = {}
+	for _,param in ipairs(params) do
+		local value = parse_value(filter.params[param.name])
+		if not (param.hide_default and value == o['default_' .. param.name]) then
+			pretty[#pretty+1] = string.format('%s: %g%s', param.name:gsub("^%l", string.upper), value, param.dB)
+		end
+	end
+
+	if #pretty == 0 then
+		pretty = ''
+	else
+		pretty = '\n(' .. table.concat(pretty, ', ') .. ')'
+	end
+
+	mp.commandv('show-text', 'Dynamic range compressor: enabled' .. pretty, o.osd_timeout)
+end
+
+local function get_filter()
+	local af = mp.get_property_native('af', {})
+
+	for i = 1, #af do
+		if af[i].label == o.filter_label then
+			return af, i
+		end
+	end
+
+	af[#af+1] = {
+		name = 'acompressor',
+		label = o.filter_label,
+		enabled = false,
+		params = {},
+	}
+
+	for _,param in pairs(params) do
+		af[#af].params[param.name] = format_value(o['default_' .. param.name], param.dB)
+	end
+
+	return af, #af
+end
+
+local function toggle_acompressor()
+	local af, i = get_filter()
+	af[i].enabled = not af[i].enabled
+	mp.set_property_native('af', af)
+	show_osd(af[i])
+end
+
+local function update_param(name, increment)
+	for _,param in pairs(params) do
+		if param.name == string.lower(name) then
+			local af, i = get_filter()
+			local value = parse_value(af[i].params[param.name])
+			value = math.max(param.min, math.min(value + increment, param.max))
+			af[i].params[param.name] = format_value(value, param.dB)
+			af[i].enabled = true
+			mp.set_property_native('af', af)
+			show_osd(af[i])
+			return
+		end
+	end
+
+	mp.msg.error('Unknown parameter "' .. name .. '"')
+end
+
+mp.add_key_binding(o.key_toggle, "toggle-acompressor", toggle_acompressor)
+mp.register_script_message('update-param', update_param)
+
+for _,param in pairs(params) do
+	for direction,step in pairs({increase=1, decrease=-1}) do
+		mp.add_key_binding(o['key_' .. direction .. '_' .. param.name],
+		                   'acompressor-' .. direction .. '-' .. param.name,
+		                   function() update_param(param.name, step*o['step_' .. param.name]); end,
+		                   { repeatable = true })
+	end
+end
+
+if o.default_enable then
+	local af, i = get_filter()
+	af[i].enabled = true
+	mp.set_property_native('af', af)
+end