main.lua

-- assert lua script
-- ===================|
-- note to escape path for winodws (c:\\users\\user\\...)

local utils = require 'mp.utils'

local danmu_file = nil
local sec_sub_visibility = mp.get_property_native("secondary-sub-visibility")
local sec_sub_ass_override = mp.get_property_native("secondary-sub-ass-override")

local function get_cid()
	local cid, danmaku_id = nil, nil
	local tracks = mp.get_property_native("track-list")
	for _, track in ipairs(tracks) do
		if track["lang"] == "danmaku" then
			cid = track["external-filename"]:match("/(%d-)%.xml$")
			danmaku_id = track["id"]
			break
		end
	end
	return cid, danmaku_id
end

local function get_sub_count()
	local count  = 0
	local tracks = mp.get_property_native("track-list")
	for _, track in ipairs(tracks) do
		if track["type"] == "sub" then
			count = count + 1
		end
	end
	return count
end

local function file_exists(path)
	if path then
		local meta = utils.file_info(path)
		return meta.is_file
	else
		return false
	end
end

-- Log function: log to both terminal and MPV OSD (On-Screen Display)
local function log(string,secs)
	secs = secs or 2.5
	mp.msg.warn(string)
	mp.osd_message(string,secs)
end

-- load function
local function load_danmu(danmu_file)
	if not file_exists(danmu_file) then return end
	log('开火')
	-- 如果可用将弹幕挂载为次字幕
	if sec_sub_ass_override then
		mp.commandv("sub-add", danmu_file, "auto")
		local sub_count = get_sub_count()
		mp.set_property_native("secondary-sub-ass-override", "yes")
		mp.set_property_native("secondary-sid", sub_count)
		mp.set_property_native("secondary-sub-visibility", true)
	else
		-- 挂载subtitles滤镜，注意加上@标签，这样即使多次调用也不会重复挂载，以最后一次为准
		mp.commandv('vf', 'append', '@danmu:subtitles=filename="'..danmu_file..'"')
		-- 只能在软解或auto-copy硬解下生效，统一改为auto-copy硬解
		mp.set_property('hwdec', 'auto-copy')
	end
end

-- download function
local function assprocess()
	local path = mp.get_property("path")
	if path and not path:find('^%a[%w.+-]-://') and not (path:find('bilibili.com') or path:find('bilivideo.com'))
	then return end
	-- get video cid
	local cid = mp.get_opt('cid')
	if cid == nil and path and path:find('^%a[%w.+-]-://') then
		cid, danmaku_id = get_cid()
		if danmaku_id ~= nil then
			mp.commandv('sub-remove', danmaku_id)
		end
	end
	if cid == nil then return end
	
	local python_path = 'python' -- path to python bin

	-- get script directory 
	local directory = mp.get_script_directory()
	local py_path = ''..directory..'/Danmu2Ass.py'

	-- under windows platform, convert path format
	if string.find(directory, "\\")
	then
		string.gsub(directory, "/", "\\")
		py_path = ''..directory..'\\Danmu2Ass.py'
	end
	local dw = mp.get_property_osd('display-width')
	local dh = mp.get_property_osd('display-height')
	local dw = mp.get_property_number('display-width', 1920)
	local dh = mp.get_property_number('display-height', 1080)
	local aspect = mp.get_property_number('width', 16) / mp.get_property_number('height', 9)
	if aspect > dw / dh then
		dh = math.floor(dw / aspect)
	elseif aspect < dw / dh then
		dw = math.floor(dh * aspect)
	end
	-- 保留底部多少高度的空白区域 (默认0, 取值0.0-1.0)
	local percent = 0.75
	-- choose to use python or .exe
	local arg = { 'python', py_path, '-d', directory, 
	-- 设置屏幕分辨率 （自动取值)
	'-s', ''..dw..'x'..dh,
	-- 设置字体大小    (默认 37.0)
	'-fs',  '37.0',
	-- 设置弹幕不透明度 (默认 0.95)
	'-a', '0.95',
	-- 滚动弹幕显示的持续时间 (默认 10秒)
	'-dm', '10.0',
	-- 静止弹幕显示的持续时间 (默认 5秒)
	'-ds', '5.0',
	'-p', tostring(math.floor(percent*dh)),
	'-r',
	cid,
}
	-- local arg = { ''..directory..'\\Danmu2Ass.exe', '-d', directory, cid}
	log('弹幕正在上膛')
	-- run python to get comments
	mp.command_native_async({
		name = 'subprocess',
		playback_only = false,
		capture_stdout = true,
		args = arg,
		capture_stdout = true
	},function(res, val, err)
		if err == nil
		then
			danmu_file = ''..directory..'/bilibili.ass'
			load_danmu(danmu_file)
		else
			log(err)
		end
	end)

end

-- toggle function
function asstoggle()
	if not file_exists(danmu_file) then return end
	local sec_visibility = mp.get_property_bool("secondary-sub-visibility")
	if sec_sub_ass_override and sec_visibility then
		log('停火')
		mp.set_property_native("secondary-sub-visibility", false)
		return
	elseif sec_sub_ass_override == nil then
		-- if exists @danmu filter， remove it
		for _, f in ipairs(mp.get_property_native('vf')) do
			if f.label == 'danmu' then
				log('停火')
				mp.commandv('vf', 'remove', '@danmu')
				return
			end
		end
	end
	-- otherwise, load danmu
	if file_exists(danmu_file) then load_danmu(danmu_file) end
end

mp.add_key_binding('b', 'toggle', asstoggle)
mp.register_event("file-loaded", assprocess)
mp.register_event("end-file", function()
	asstoggle()
	if sec_sub_ass_override then
		mp.set_property_native("secondary-sub-visibility", sec_sub_visibility)
		mp.set_property_native("secondary-sub-ass-override", sec_sub_ass_override)
	end
end)