TOOLS/lua: add autodeint.lua

This isn't quite as robust as idet.sh as the default detection
interval is only 4 seconds vs 35 for idet.sh. idet.sh can have such a
large sample time since it turns off the vo and uses --untimed, which
is currently not possible from lua.

TOOLS/lua/autodeint.lua

@@ -0,0 +1,164 @@
+-- This script uses the lavfi idet filter to automatically insert the
+-- appropriate deinterlacing filter based on a short section of the
+-- currently playing video.
+--
+-- It registers the key-binding ctrl+d, which when pressed, inserts
+-- the filter vf=lavfi=idet. After 4 second, it examines the results
+-- to determine whether the content progressive or interlaced and the
+-- interlacing field dominance. It immediately sets the latter within
+-- mpv.
+--
+-- If the content is judged not to be progressive, it may be either
+-- interlaced or telecined. To determine which one, the video is
+-- seeked back to the detection starting point with the "pullup"
+-- filter inserted. After another four seconds, if idet thinks that
+-- the pulled up viedo is "progressive", then pullup is the correct
+-- filter and this script leaves it in places while removing the idet
+-- filter. Otherwise, the content plain interlaced and mpv's deinterlace
+-- property is set. This will usually insert the yadif deinterlacing filter.
+--
+-- The default detection time may be overridden by adding
+--
+-- --lua-opts=autodeint.detect_seconds=<number of seconds>
+--
+-- to mpv's arguments. This may be desirable to allow idet more
+-- time to collect data.
+--
+-- To see counts of the various types of frames for each detection phase,
+-- the verbosity can be increased with
+--
+-- --msg-level autodeint=v
+--
+-- This script requires a recent version of ffmpeg for which the idet
+-- filter adds the required metadata.
+
+require "mp.msg"
+
+script_name = mp.get_script_name()
+detect_label = string.format("%s-detect", script_name)
+pullup_label = string.format("%s", script_name)
+
+-- number of seconds to gather cropdetect data
+detect_seconds = tonumber(mp.get_opt(string.format("%s.detect_seconds", script_name)))
+if not detect_seconds then
+    detect_seconds = 4
+end
+
+function del_filter_if_present(label)
+    -- necessary because mp.command('vf del @label:filter') raises an
+    -- error if the filter doesn't exist
+    local vfs = mp.get_property_native("vf")
+
+    for i,vf in pairs(vfs) do
+        if vf["label"] == label then
+            table.remove(vfs, i)
+            mp.set_property_native("vf", vfs)
+            return true
+        end
+    end
+    return false
+end
+
+function start_detect()
+    -- exit if detection is already in progress
+    if timer then
+        mp.msg.warn("already detecting!")
+        return
+    end
+
+    mp.set_property("deinterlace","no")
+    del_filter_if_present(pullup_label)
+
+    percent_pos = mp.get_property("percent-pos")
+
+    -- insert the detection filter
+    local cmd = string.format('vf add @%s:lavfi=graph="idet"', detect_label)
+    if not mp.command(cmd) then
+        mp.msg.error("failed to insert detection filter")
+        return
+    end
+
+    -- wait to gather data
+    timer = mp.add_timeout(detect_seconds, judge_field_dominance)
+end
+
+function stop_detect()
+    del_filter_if_present(detect_label)
+    timer = nil
+    mp.set_property("playback-pos", percent_pos)
+end
+
+progressive, interlaced_tff, interlaced_bff, interlaced = 0, 1, 2, 3, 4
+
+function judge()
+    -- get the metadata
+    local result = mp.get_property_native(string.format("vf-metadata/%s", detect_label))
+    num_tff          = tonumber(result["lavfi.idet.multiple.tff"])
+    num_bff          = tonumber(result["lavfi.idet.multiple.bff"])
+    num_progressive  = tonumber(result["lavfi.idet.multiple.progressive"])
+    num_undetermined = tonumber(result["lavfi.idet.multiple.undetermined"])
+    num_interlaced   = num_tff + num_bff
+    num_determined   = num_interlaced + num_progressive
+
+    mp.msg.verbose("progressive    = "..num_progressive)
+    mp.msg.verbose("interlaced-tff = "..num_tff)
+    mp.msg.verbose("interlaced-bff = "..num_bff) 
+    mp.msg.verbose("undetermined   = "..num_undetermined)
+
+    if num_determined < num_undetermined then
+        mp.msg.warn("majority undetermined frames")
+    end
+    if num_progressive > 20*num_interlaced then
+        return progressive
+    elseif num_tff > 10*num_bff then
+        return interlaced_tff
+    elseif num_bff > 10*num_tff then
+        return interlaced_bff
+    else
+        return interlaced
+    end
+end
+
+function judge_field_dominance()
+    verdict = judge()
+    if verdict == progressive then
+        stop_detect()
+        mp.msg.info("progressive: doing nothing")
+        return
+    elseif verdict == interlaced_tff then
+        mp.set_property("field-dominance", "top")
+    elseif verdict == interlaced_bff then
+        mp.set_property("field-dominance", "bottom")
+    elseif verdict == interlaced then
+        mp.set_property("field-dominance", "auto")
+    end
+
+    local cmd = string.format("vf pre @%s:pullup", pullup_label)
+    if not mp.command(cmd) then
+        mp.msg.error("failed to insert pullup filter")
+        stop_detect()
+        return
+    end
+
+    -- redo the detection with the pullup filter to see if it's telecined
+    mp.set_property("percent-pos", percent_pos)
+    timer = mp.add_timeout(detect_seconds, judge_ivtc)
+end
+
+function judge_ivtc()
+    verdict = judge()
+
+    if verdict == progressive then
+        mp.msg.info(string.format("telecinied with %s field dominance: using pullup", mp.get_property("field-dominance")))
+        stop_detect()
+    else
+        mp.msg.info(string.format("interlaced with %s field dominance: setting deinterlace property", mp.get_property("field-dominance")))
+        del_filter_if_present(pullup_label)
+        mp.set_property("deinterlace","yes")
+        stop_detect()
+    end
+
+    return
+end
+
+mp.add_key_binding("ctrl+d", script_name, start_detect)