mpv-webp.lua

-- Original by Scheliux, Dragoner7 which was ported from Ruin0x11
-- Adapted to webp by DonCanjas

-- Create animated webps with mpv
-- Requires ffmpeg.
-- Adapted from https://github.com/Scheliux/mpv-gif-generator
-- Usage: "w" to set start frame, "W" to set end frame, "Ctrl+w" to create.

--  Note:
--     Requires FFmpeg in PATH environment variable or edit ffmpeg_path in the script options,
--     for example, by replacing "ffmpeg" with "C:\Programs\ffmpeg\bin\ffmpeg.exe"
--  Note: 
--     A small circle at the top-right corner is a sign that creat is happenning now.

require 'mp.options'
local msg = require 'mp.msg'
local utils = require "mp.utils"

local options = {
    ffmpeg_path = "ffmpeg",
    dir = "~~desktop/",
    rez = 600,
    fps = 15,
    lossless = 0,
    quality = 90,
    compression_level = 6,
    loop = 0,
}

read_options(options, "webp")


local fps

-- Check for invalid fps values
-- Can you believe Lua doesn't have a proper ternary operator in the year of our lord 2020?
if options.fps ~= nil and options.fps >= 1 and options.fps < 30 then
    fps = options.fps
else
    fps = 15
end

-- Set this to the filters to pass into ffmpeg's -vf option.
-- filters="fps=24,scale=320:-1:flags=spline"
filters=string.format("fps=%s,zscale='trunc(ih*dar/2)*2:trunc(ih/2)*2':f=spline36,setsar=1/1,zscale=%s:-1:f=spline36", fps, options.rez)  

-- Setup output directory
local output_directory = mp.command_native({ "expand-path", options.dir })
--create output_directory if it doesn't exist
if utils.readdir(output_directory) == nil then
    local args = { 'powershell', '-NoProfile', '-Command', 'mkdir', output_directory }
    local res = mp.command_native({name = "subprocess", capture_stdout = true, playback_only = false, args = args})
    if res.status ~= 0 then
        msg.error("Failed to create webp_dir save directory "..output_directory..". Error: "..(res.error or "unknown"))
        return
    end
end

start_time = -1
end_time = -1

function make_webp_with_subtitles()
    make_webp_internal(true)
end

function make_webp()
    make_webp_internal(false)
end    

function table_length(t)
    local count = 0
    for _ in pairs(t) do count = count + 1 end
    return count
end


function make_webp_internal(burn_subtitles)
    local start_time_l = start_time
    local end_time_l = end_time
    if start_time_l == -1 or end_time_l == -1 or start_time_l >= end_time_l then
        mp.osd_message("Invalid start/end time.")
        return
    end

    msg.info("Creating webP.")
    mp.osd_message("Creating webP.")

    -- shell escape
    function esc_for_sub(s)
        s = string.gsub(s, [[\]], [[/]])
        s = string.gsub(s, '"', '"\\""')
        s = string.gsub(s, ":", [[\\:]])
        s = string.gsub(s, "'", [[\\']])
        s = string.gsub(s, "%[", "\\%[")
        s = string.gsub(s, "%]", "\\%]")
        return s
    end

    local pathname = mp.get_property("path", "")
    local trim_filters = filters

    local position = start_time_l
    local duration = end_time_l - start_time_l

    if burn_subtitles then
        -- Determine currently active sub track

        local i = 0
        local tracks_count = mp.get_property_number("track-list/count")
        local subs_array = {}
        
        -- check for subtitle tracks

        while i < tracks_count do
            local type = mp.get_property(string.format("track-list/%d/type", i))
            local selected = mp.get_property(string.format("track-list/%d/selected", i))
            local external = mp.get_property(string.format("track-list/%d/external", i))

            -- if it's a sub track, save it

            if type == "sub" then
                local length = table_length(subs_array)
                if selected == "yes" and external == "yes" then
                    msg.info("Error: external subtitles have been selected")
                    mp.osd_message("Error: external subtitles have been selected", 2)
                    return
                else
                    subs_array[length] = selected == "yes"
                end
            end
            i = i + 1
        end

        if table_length(subs_array) > 0 then

            local correct_track = 0

            -- iterate through saved subtitle tracks until the correct one is found

            for index, is_selected in pairs(subs_array) do
                if (is_selected) then
                    correct_track = index
                end
            end

            trim_filters = trim_filters .. string.format(",subtitles='%s':si=%s", esc_for_sub(pathname), correct_track)

        end

    end

    -- make the webp
    local filename = mp.get_property("filename/no-ext")
    local file_path = output_directory .. "/" .. filename

    -- increment filename
    for i=0,999 do
        local fn = string.format('%s_%03d.webp', file_path, i)
        if not file_exists(fn) then
            webpname = fn
            break
        end
    end
    if not webpname then
        mp.osd_message('No available filenames!')
        return
    end

    local copyts = ""

    if burn_subtitles then
        copyts = "-copyts"
    end

    cmd = string.format("%s -y -hide_banner -loglevel error -ss %s %s -t %s -i '%s' -lavfi %s -lossless %s -q:v %s -compression_level %s -loop %s '%s'", options.ffmpeg_path, position, copyts, duration, pathname, trim_filters, options.lossless, options.quality, options.compression_level, options.loop, webpname)
    args =  { 'powershell', '-NoProfile', '-Command', cmd }
    local screenx, screeny, aspect = mp.get_osd_size()
    mp.set_osd_ass(screenx, screeny, "{\\an9}● ")
    local res = mp.command_native({name = "subprocess", capture_stdout = true, playback_only = false, args = args})
    mp.set_osd_ass(screenx, screeny, "")
    if res.status ~= 0 then
        msg.info("Failed to creat webP.")
        mp.osd_message("Error creating webP, check console for more info.")
        return
    end
    msg.info("webP created.")
    mp.osd_message("webP created.")
end

function set_webp_start()
    start_time = mp.get_property_number("time-pos", -1)
    mp.osd_message("webP Start: " .. start_time)
end

function set_webp_end()
    end_time = mp.get_property_number("time-pos", -1)
    mp.osd_message("webP End: " .. end_time)
end

function file_exists(name)
    local f=io.open(name,"r")
    if f~=nil then io.close(f) return true else return false end
end

mp.add_key_binding("w", "set_webp_start", set_webp_start)
mp.add_key_binding("W", "set_webp_end", set_webp_end)
mp.add_key_binding("Ctrl+w", "make_webp", make_webp)
mp.add_key_binding("Ctrl+W", "make_webp_with_subtitles", make_webp_with_subtitles) --only works with srt for now