TOOLS/autocrop.lua: automatically crop at startup

TOOLS/lua/autocrop.lua

@@ -1,114 +1,322 @@
--- This script uses the lavfi cropdetect filter to automatically
--- insert a crop filter with appropriate parameters for the currently
--- playing video.
---
--- It registers the key-binding "C" (shift+c), which when pressed,
--- inserts the filter vf=lavfi=cropdetect. After 1 second, it then
--- inserts the filter vf=crop=w:h:x:y, where w,h,x,y are determined
--- from the vf-metadata gathered by cropdetect. The cropdetect filter
--- is removed immediately after the crop filter is inserted as it is
--- no longer needed.
---
--- If the "C" key is pressed again, the crop filter is removed
--- restoring playback to its original state.
---
--- Since the crop parameters are determined from the 1 second of video
--- between inserting the cropdetect and crop filters, the "C" key
--- should be pressed at a position in the video where the crop region
--- is unambiguous (i.e., not a black frame, black background title
--- card, or dark scene).
---
--- The default delay between insertion of the cropdetect and
--- crop filters may be overridden by adding
---
--- --script-opts=autocrop.detect_seconds=<number of seconds>
---
--- to mpv's arguments. This may be desirable to allow cropdetect more
--- time to collect data.
+--[[
+This script uses the lavfi cropdetect filter to automatically
+insert a crop filter with appropriate parameters for the
+currently playing video.
+
+It will automatically crop the video, when playback starts.
+
+Also It registers the key-binding "C" (shift+c). You can manually
+crop the video by pressing the "C" (shift+c) key.
+
+If the "C" key is pressed again, the crop filter is removed
+restoring playback to its original state.
+
+The workflow is as follows: First, it inserts the filter
+vf=lavfi=cropdetect. After <detect_seconds> (default is 1)
+seconds, it then inserts the filter vf=crop=w:h:x:y, where
+w,h,x,y are determined from the vf-metadata gathered by
+cropdetect. The cropdetect filter is removed immediately after
+the crop filter is inserted as it is no longer needed.
+
+Since the crop parameters are determined from the 1 second of
+video between inserting the cropdetect and crop filters, the "C"
+key should be pressed at a position in the video where the crop
+region is unambiguous (i.e., not a black frame, black background
+title card, or dark scene).
+
+The default options can be overridden by adding
+script-opts-append=autocrop-<parameter>=<value> into mpv.conf
+
+List of available parameters (For default values, see <options>)：
+
+auto: bool - Whether to automatically apply crop at the start of
+    playback. If you don't want to crop automatically, set it to
+    false or add "script-opts-append=autocrop-auto=no" into
+    mpv.conf.
+
+auto_delay: seconds - Delay before starting crop in auto mode.
+    You can try to increase this value to avoid dark scene or
+    fade in at beginning. Automatic cropping will not occur if
+    the value is larger than the remaining playback time.
+
+detect_limit: number[0-255] - Black threshold for cropdetect.
+    Smaller values will generally result in less cropping.
+    See limit of https://ffmpeg.org/ffmpeg-filters.html#cropdetect
+
+detect_round: number[2^n] -  The value which the width/height
+    should be divisible by. Smaller values ​​have better detection
+    accuracy. If you have problems with other filters,
+    you can try to set it to 4 or 16.
+    See round of https://ffmpeg.org/ffmpeg-filters.html#cropdetect
+
+detect_min_ratio: number[0.0-1.0] - The ratio of the minimum clip
+    size to the original. If the picture is over cropped or under
+    cropped, try adjusting this value.
+
+detect_seconds: seconds - How long to gather cropdetect data.
+    Increasing this may be desirable to allow cropdetect more
+    time to collect data.
+--]]
+
 require "mp.msg"
+require 'mp.options'
 
-script_name = mp.get_script_name()
-cropdetect_label = string.format("%s-cropdetect", script_name)
-crop_label = string.format("%s-crop", 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
+local options = {
+    auto = true,
+    auto_delay = 4,
+    detect_limit = "24/255",
+    detect_round = 2,
+    detect_min_ratio = 0.5,
     detect_seconds = 1
-end
+}
+read_options(options)
 
-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)
+local label_prefix = mp.get_script_name()
+local labels = {
+    crop = string.format("%s-crop", label_prefix),
+    cropdetect = string.format("%s-cropdetect", label_prefix)
+}
+
+timers = {
+    auto_delay = nil,
+    detect_crop = nil
+}
+
+function is_filter_present(label)
+    local filters = mp.get_property_native("vf")
+    for index, filter in pairs(filters) do
+        if filter["label"] == label then
             return true
         end
     end
     return false
 end
 
-function autocrop_start()
-    -- exit if cropdetection is already in progress
-    if timer then
-        mp.msg.warn("already cropdetecting!")
-        return
-    end
+function is_enough_time(seconds)
 
-    -- if there's a crop filter, remove it and exit
-    if del_filter_if_present(crop_label) then
-        return
-    end
+    -- Plus 1 second for deviation.
+    local time_needed = seconds + 1
+    local playtime_remaining = mp.get_property_native("playtime-remaining")
 
-    -- insert the cropdetect filter
-    ret=mp.command(
-        string.format(
-            'vf add @%s:cropdetect=limit=%f:round=2:reset=0',
-            cropdetect_label, 24/255
-        )
-    )
-    -- wait to gather data
-    timer=mp.add_timeout(detect_seconds, do_crop)
+    return playtime_remaining and time_needed < playtime_remaining
 end
 
-function do_crop()
-    -- get the metadata
-    local cropdetect_metadata = mp.get_property_native(
-        string.format("vf-metadata/%s", cropdetect_label)
-    )
+function is_cropable()
+    local vid = mp.get_property_native("vid")
+    local is_album = vid and mp.get_property_native(
+        string.format("track-list/%d/albumart", vid)
+    ) or false
 
-    -- use it to crop if its valid
-    if cropdetect_metadata then
-        if cropdetect_metadata["lavfi.cropdetect.w"]
-            and cropdetect_metadata["lavfi.cropdetect.h"]
-            and cropdetect_metadata["lavfi.cropdetect.x"]
-            and cropdetect_metadata["lavfi.cropdetect.y"]
-        then
-            mp.command(string.format("vf add @%s:lavfi-crop=w=%s:h=%s:x=%s:y=%s",
-                                     crop_label,
-                                     cropdetect_metadata["lavfi.cropdetect.w"],
-                                     cropdetect_metadata["lavfi.cropdetect.h"],
-                                     cropdetect_metadata["lavfi.cropdetect.x"],
-                                     cropdetect_metadata["lavfi.cropdetect.y"]))
-        else
-            mp.msg.error(
-                "Got empty crop data. You might need to increase detect_seconds."
-            )
+    return vid and not is_album
+end
+
+function remove_filter(label)
+    if is_filter_present(label) then
+        mp.command(string.format('vf remove @%s', label))
+        return true
+    end
+    return false
+end
+
+function cleanup()
+
+    -- Remove all existing filters.
+    for key, value in pairs(labels) do
+        remove_filter(value)
+    end
+
+    -- Kill all timers.
+    for index, timer in pairs(timers) do
+        if timer then
+            timer:kill()
+            timer = nil
         end
-    else
-        mp.msg.error(
-            "No crop data. Was the cropdetect filter successfully inserted?"
-        )
-        mp.msg.error(
-            "Does your version of ffmpeg/libav support AVFrame metadata?"
-        )
     end
-    -- remove the cropdetect filter
-    del_filter_if_present(cropdetect_label)
-    timer=nil
 end
 
-mp.add_key_binding("C", "auto_crop", autocrop_start)
+function detect_crop()
+
+    -- If it's not cropable, exit.
+    if not is_cropable() then
+        mp.msg.warn("autocrop only works for videos.")
+        return
+    end
+
+    -- Verify if there is enough time to detect crop.
+    local time_needed = options.detect_seconds
+
+    if not is_enough_time(time_needed) then
+        mp.msg.warn("Not enough time to detect crop.")
+        return
+    end
+
+    -- Insert the cropdetect filter.
+    local limit = options.detect_limit
+    local round = options.detect_round
+
+    mp.command(
+        string.format(
+            'vf pre @%s:cropdetect=limit=%s:round=%d:reset=0',
+            labels.cropdetect, limit, round
+        )
+    )
+
+    -- Wait to gather data.
+    timers.detect_crop = mp.add_timeout(time_needed, detect_end)
+end
+
+function detect_end()
+
+    -- Get the metadata and remove the cropdetect filter.
+    local cropdetect_metadata =
+        mp.get_property_native(
+            string.format("vf-metadata/%s",
+            labels.cropdetect
+        )
+    )
+    remove_filter(labels.cropdetect)
+
+    -- Remove the timer of detect crop.
+    if timers.detect_crop then
+        timers.detect_crop:kill()
+        timers.detect_crop = nil
+    end
+
+    local meta = {}
+
+    -- Verify the existence of metadata.
+    if cropdetect_metadata then
+        meta = {
+            w = cropdetect_metadata["lavfi.cropdetect.w"],
+            h = cropdetect_metadata["lavfi.cropdetect.h"],
+            x = cropdetect_metadata["lavfi.cropdetect.x"],
+            y = cropdetect_metadata["lavfi.cropdetect.y"],
+        }
+    else
+        mp.msg.error("No crop data.")
+        mp.msg.info("Was the cropdetect filter successfully inserted?")
+        mp.msg.info("Does your version of ffmpeg/libav support AVFrame metadata?")
+        return
+    end
+
+    -- Verify that the metadata meets the requirements and convert it.
+    if meta.w and meta.h and meta.x and meta.y then
+        local width = mp.get_property_native("width")
+        local height = mp.get_property_native("height")
+
+        meta = {
+            w = tonumber(meta.w),
+            h = tonumber(meta.h),
+            x = tonumber(meta.x),
+            y = tonumber(meta.y),
+            min_w = width * options.detect_min_ratio,
+            min_h = height * options.detect_min_ratio,
+            max_w = width,
+            max_h = height
+        }
+    else
+        mp.msg.error("Got empty crop data.")
+        mp.msg.info("You might need to increase detect_seconds.")
+        return
+    end
+
+    apply_crop(meta)
+end
+
+function apply_crop(meta)
+
+    -- Verify if it is necessary to crop.
+    local is_effective = meta.x > 0 or meta.y > 0
+        or meta.w < meta.max_w or meta.h < meta.max_h
+
+    if not is_effective then
+        mp.msg.info("No area detected for cropping.")
+        return
+    end
+
+    -- Verify it is not over cropped.
+    local is_excessive = meta.w < meta.min_w and meta.h < meta.min_h
+
+    if is_excessive then
+        mp.msg.info("The area to be cropped is too large.")
+        mp.msg.info("You might need to decrease detect_min_ratio.")
+        return
+    end
+
+    -- Remove existing crop.
+    remove_filter(labels.crop)
+
+    -- Apply crop.
+    mp.command(
+        string.format("vf pre @%s:lavfi-crop=w=%s:h=%s:x=%s:y=%s",
+            labels.crop, meta.w, meta.h, meta.x, meta.y
+        )
+    )
+end
+
+function on_start()
+
+    -- Clean up at the beginning.
+    cleanup()
+
+    -- If auto is not true, exit.
+    if not options.auto then
+        return
+    end
+
+    -- If it is the beginning, wait for detect_crop
+    -- after auto_delay seconds, otherwise immediately.
+    local playback_time = mp.get_property_native("playback-time")
+    local is_delay_needed = playback_time
+        and options.auto_delay > playback_time
+
+    if is_delay_needed then
+
+        -- Verify if there is enough time for autocrop.
+        local time_needed = options.auto_delay + options.detect_seconds
+
+        if not is_enough_time(time_needed) then
+            mp.msg.warn("Not enough time for autocrop.")
+            return
+        end
+
+        timers.auto_delay = mp.add_timeout(time_needed,
+            function()
+                detect_crop()
+
+                -- Remove the timer of auto delay.
+                timers.auto_delay:kill()
+                timers.auto_delay = nil
+            end
+        )
+    else
+        detect_crop()
+    end
+end
+
+function on_toggle()
+
+    -- If it is during auto_delay, kill the timer.
+    if timers.auto_delay then
+        timers.auto_delay:kill()
+        timers.auto_delay = nil
+    end
+
+    -- Cropped => Remove it.
+    if remove_filter(labels.crop) then
+        return
+    end
+
+    -- Detecting => Leave it.
+    if timers.detect_crop then
+        mp.msg.warn("Already cropdetecting!")
+        return
+    end
+
+    -- Neither => Do delectcrop.
+    detect_crop()
+end
+
+mp.add_key_binding("C", "toggle_crop", on_toggle)
+mp.register_event("end-file", cleanup)
+mp.register_event("file-loaded", on_start)