From 9e4722da4ef66e4790b52dcfe96d8efc2343c3d5 Mon Sep 17 00:00:00 2001
From: ksyasuda <ksyasuda@umich.edu>
Date: Mon, 1 Nov 2021 00:24:43 -0700
Subject: [PATCH] add skip-intro.lua script and modify setup

---
 skip-intro.lua | 151 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 151 insertions(+)
 create mode 100644 skip-intro.lua

diff --git a/skip-intro.lua b/skip-intro.lua
new file mode 100644
index 0000000..8d6b510
--- /dev/null
+++ b/skip-intro.lua
@@ -0,0 +1,151 @@
+MAX_SPEED = 100
+NORMAL_SPEED = 1
+ONE_SECOND = 1
+skip = false
+-- Max noise (dB) and min silence duration (s) to trigger
+opts = { quietness = -45, duration = 0.85 }
+
+
+function setOptions()
+    local options = require 'mp.options'
+    options.read_options(opts)
+end
+
+function setTime(time)
+    mp.set_property_number('time-pos', time)
+end
+
+function getTime()
+    return mp.get_property_native('time-pos')
+end
+
+function setSpeed(speed)
+    mp.set_property('speed', speed)
+end
+
+function setPause(state)
+    mp.set_property_bool('pause', state)
+end
+
+function setMute(state)
+    mp.set_property_bool('mute', state)
+end
+
+function initAudioFilter()
+    local af_table = mp.get_property_native('af')
+    af_table[#af_table + 1] = {
+        enabled = false,
+        label   = 'silencedetect',
+        name    = 'lavfi',
+        params  = { graph = 'silencedetect=noise=' .. opts.quietness .. 'dB:d=' .. opts.duration }
+    }
+    mp.set_property_native('af', af_table)
+end
+
+function initVideoFilter()
+    local vf_table = mp.get_property_native('vf')
+    vf_table[#vf_table + 1] = {
+        enabled = false,
+        label   = 'blackout',
+        name    = 'lavfi',
+        params  = { graph = '' }
+    }
+    mp.set_property_native('vf', vf_table)
+end
+
+function setAudioFilter(state)
+    local af_table = mp.get_property_native('af')
+    if #af_table > 0 then
+        for i = #af_table, 1, -1 do
+            if af_table[i].label == 'silencedetect' then
+                af_table[i].enabled = state
+                mp.set_property_native('af', af_table)
+                break
+            end
+        end
+    end
+end
+
+function dim(state)
+    local dim = { width = 0, height = 0 }
+    if state == true then
+        dim.width = mp.get_property_native('width')
+        dim.height = mp.get_property_native('height')
+    end
+    return dim.width .. 'x' .. dim.height
+end
+
+function setVideoFilter(state)
+    local vf_table = mp.get_property_native('vf')
+    if #vf_table > 0 then
+        for i = #vf_table, 1, -1 do
+            if vf_table[i].label == 'blackout' then
+                vf_table[i].enabled = state
+                vf_table[i].params  = { graph = 'nullsink,color=c=black:s=' .. dim(state) }
+                mp.set_property_native('vf', vf_table)
+                break
+            end
+        end
+    end
+end
+
+function silenceTrigger(name, value)
+    if value == '{}' or value == nil then
+        return
+    end
+
+    local skipTime = tonumber(string.match(value, '%d+%.?%d+'))
+    local currTime = getTime()
+
+    if skipTime == nil or skipTime < currTime + ONE_SECOND then
+        return
+    end
+
+    stopSkip()
+    setTime(skipTime)
+    skip = false
+end
+
+function setAudioTrigger(state)
+    if state == true then
+        mp.observe_property('af-metadata/silencedetect', 'string', silenceTrigger)
+    else
+        mp.unobserve_property(silenceTrigger)   
+    end
+end
+
+function startSkip()
+    startTime = getTime()
+    -- This audio filter detects moments of silence
+    setAudioFilter(true)
+    -- This video filter makes fast-forward faster
+    setVideoFilter(true)
+    setAudioTrigger(true)
+    setPause(false)
+    setMute(true)
+    setSpeed(MAX_SPEED)
+end
+
+function stopSkip()
+    setAudioFilter(false)
+    setVideoFilter(false)
+    setAudioTrigger(false)
+    setMute(false)
+    setSpeed(NORMAL_SPEED)
+end
+
+function keypress()
+    skip = not skip
+    if skip then
+        startSkip()
+    else
+        stopSkip()
+        setTime(startTime)
+    end
+end
+
+setOptions(opts)
+initAudioFilter()
+initVideoFilter()
+
+mp.add_key_binding('Tab', 'skip-key', keypress)