Program: CWE-20
Project: CVE-2018-6835
Buggy source:
local utils = require 'mp.utils'
local msg = require 'mp.msg'
local options = require 'mp.options'

local o = {
    exclude = "",
    try_ytdl_first = false
}
options.read_options(o)

local ytdl = {
    path = "youtube-dl",
    searched = false,
    blacklisted = {}
}

local chapter_list = {}

local function exec(args)
    local ret = utils.subprocess({args = args})
    return ret.status, ret.stdout, ret
end

-- return true if it was explicitly set on the command line
local function option_was_set(name)
    return mp.get_property_bool("option-info/" ..name.. "/set-from-commandline",
                                false)
end

-- return true if the option was set locally
local function option_was_set_locally(name)
    return mp.get_property_bool("option-info/" ..name.. "/set-locally", false)
end

-- youtube-dl may set special http headers for some sites (user-agent, cookies)
local function set_http_headers(http_headers)
    if not http_headers then
        return
    end
    local headers = {}
    local useragent = http_headers["User-Agent"]
    if useragent and not option_was_set("user-agent") then
        mp.set_property("file-local-options/user-agent", useragent)
    end
    local additional_fields = {"Cookie", "Referer", "X-Forwarded-For"}
    for idx, item in pairs(additional_fields) do
        local field_value = http_headers[item]
        if field_value then
            headers[#headers + 1] = item .. ": " .. field_value
        end
    end
    if #headers > 0 and not option_was_set("http-header-fields") then
        mp.set_property_native("file-local-options/http-header-fields", headers)
    end
end

local function append_rtmp_prop(props, name, value)
    if not name or not value then
        return props
    end

    if props and props ~= "" then
        props = props..","
    else
        props = ""
    end

    return props..name.."=\""..value.."\""
end

local function edl_escape(url)
    return "%" .. string.len(url) .. "%" .. url
end

local function time_to_secs(time_string)
    local ret

    local a, b, c = time_string:match("(%d+):(%d%d?):(%d%d)")
    if a ~= nil then
        ret = (a*3600 + b*60 + c)
    else
        a, b = time_string:match("(%d%d?):(%d%d)")
        if a ~= nil then
            ret = (a*60 + b)
        end
    end

    return ret
end

local function extract_chapters(data, video_length)
    local ret = {}

    for line in data:gmatch("[^\r\n]+") do
        local time = time_to_secs(line)
        if time and (time < video_length) then
            table.insert(ret, {time = time, title = line})
        end
    end
    table.sort(ret, function(a, b) return a.time < b.time end)
    return ret
end

local function is_blacklisted(url)
    if o.exclude == "" then return false end
    if #ytdl.blacklisted == 0 then
        local joined = o.exclude
        while joined:match('%|?[^|]+') do
            local _, e, substring = joined:find('%|?([^|]+)')
            table.insert(ytdl.blacklisted, substring)
            joined = joined:sub(e+1)
        end
    end
    if #ytdl.blacklisted > 0 then
        url = url:match('https?://(.+)')
        for _, exclude in ipairs(ytdl.blacklisted) do
            if url:match(exclude) then
                msg.verbose('URL matches excluded substring. Skipping.')
                return true
            end
        end
    end
    return false
end

local function make_absolute_url(base_url, url)
    if url:find("https?://") == 1 then return url end

    local proto, domain, rest =
        base_url:match("(https?://)([^/]+/)(.*)/?")
    local segs = {}
    rest:gsub("([^/]+)", function(c) table.insert(segs, c) end)
    url:gsub("([^/]+)", function(c) table.insert(segs, c) end)
    local resolved_url = {}
    for i, v in ipairs(segs) do
        if v == ".." then
            table.remove(resolved_url)
        elseif v ~= "." then
            table.insert(resolved_url, v)
        end
    end
    return proto .. domain ..
        table.concat(resolved_url, "/")
end

local function join_url(base_url, fragment)
    local res = ""
    if base_url and fragment.path then
        res = make_absolute_url(base_url, fragment.path)
    elseif fragment.url then
        res = fragment.url
    end
    return res
end

local function edl_track_joined(fragments, protocol, is_live, base)
    if not (type(fragments) == "table") or not fragments[1] then
        msg.debug("No fragments to join into EDL")
        return nil
    end

    local edl = "edl://"
    local offset = 1
    local parts = {}

    if (protocol == "http_dash_segments") and
        not fragments[1].duration and not is_live then
        -- assume MP4 DASH initialization segment
        table.insert(parts,
            "!mp4_dash,init=" .. edl_escape(join_url(base, fragments[1])))
        offset = 2

        -- Check remaining fragments for duration;
        -- if not available in all, give up.
        for i = offset, #fragments do
            if not fragments[i].duration then
                msg.error("EDL doesn't support fragments" ..
                         "without duration with MP4 DASH")
                return nil
            end
        end
    end

    for i = offset, #fragments do
        local fragment = fragments[i]
        table.insert(parts, edl_escape(join_url(base, fragment)))
        if fragment.duration then
            parts[#parts] =
                parts[#parts] .. ",length="..fragment.duration
        end
    end
    return edl .. table.concat(parts, ";") .. ";"
end

local function has_native_dash_demuxer()
    local demuxers = mp.get_property_native("demuxer-lavf-list")
    for _,v in ipairs(demuxers) do
        if v == "dash" then
            return true
        end
    end
    return false
end

local function proto_is_dash(json)
    local reqfmts = json["requested_formats"]
    return (reqfmts ~= nil and reqfmts[1]["protocol"] == "http_dash_segments")
           or json["protocol"] == "http_dash_segments"
end

local function add_single_video(json)
    local streamurl = ""
    local max_bitrate = 0

    if has_native_dash_demuxer() and proto_is_dash(json) then
        local mpd_url = json["requested_formats"][1]["manifest_url"] or
            json["manifest_url"]
        if not mpd_url then
            msg.error("No manifest URL found in JSON data.")
            return
        end

        streamurl = mpd_url

        if json.requested_formats then
            for _, track in pairs(json.requested_formats) do
                max_bitrate = track.tbr > max_bitrate and
                    track.tbr or max_bitrate
            end
        elseif json.tbr then
            max_bitrate = json.tbr > max_bitrate and json.tbr or max_bitrate
        end

    -- DASH/split tracks
    elseif not (json["requested_formats"] == nil) then
        for _, track in pairs(json.requested_formats) do
            local edl_track = nil
            edl_track = edl_track_joined(track.fragments,
                track.protocol, json.is_live,
                track.fragment_base_url)
            if track.acodec and track.acodec ~= "none" then
                -- audio track
                mp.commandv("audio-add",
                    edl_track or track.url, "auto",
                    track.format_note or "")
            elseif track.vcodec and track.vcodec ~= "none" then
                -- video track
                streamurl = edl_track or track.url
            end
        end

    elseif not (json.url == nil) then
        local edl_track = nil
        edl_track = edl_track_joined(json.fragments, json.protocol,
            json.is_live, json.fragment_base_url)

        -- normal video or single track
        streamurl = edl_track or json.url
        set_http_headers(json.http_headers)
    else
        msg.error("No URL found in JSON data.")
        return
    end

    msg.debug("streamurl: " .. streamurl)

    mp.set_property("stream-open-filename", streamurl:gsub("^data:", "data://", 1))

    mp.set_property("file-local-options/force-media-title", json.title)

    -- set hls-bitrate for dash track selection
    if max_bitrate > 0 and
        not option_was_set("hls-bitrate") and
        not option_was_set_locally("hls-bitrate") then
        mp.set_property_native('file-local-options/hls-bitrate', max_bitrate*1000)
    end

    -- add subtitles
    if not (json.requested_subtitles == nil) then
        for lang, sub_info in pairs(json.requested_subtitles) do
            msg.verbose("adding subtitle ["..lang.."]")

            local sub = nil

            if not (sub_info.data == nil) then
                sub = "memory://"..sub_info.data
            elseif not (sub_info.url == nil) then
                sub = sub_info.url
            end

            if not (sub == nil) then
                mp.commandv("sub-add", sub,
                    "auto", sub_info.ext, lang)
            else
                msg.verbose("No subtitle data/url for ["..lang.."]")
            end
        end
    end

    -- add chapters
    if json.chapters then
        msg.debug("Adding pre-parsed chapters")
        for i = 1, #json.chapters do
            local chapter = json.chapters[i]
            local title = chapter.title or ""
            if title == "" then
                title = string.format('Chapter %02d', i)
            end
            table.insert(chapter_list, {time=chapter.start_time, title=title})
        end
    elseif not (json.description == nil) and not (json.duration == nil) then
        chapter_list = extract_chapters(json.description, json.duration)
    end

    -- set start time
    if not (json.start_time == nil) and
        not option_was_set("start") and
        not option_was_set_locally("start") then
        msg.debug("Setting start to: " .. json.start_time .. " secs")
        mp.set_property("file-local-options/start", json.start_time)
    end

    -- set aspect ratio for anamorphic video
    if not (json.stretched_ratio == nil) and
        not option_was_set("video-aspect") then
        mp.set_property('file-local-options/video-aspect', json.stretched_ratio)
    end

    -- for rtmp
    if (json.protocol == "rtmp") then
        local rtmp_prop = append_rtmp_prop(nil,
            "rtmp_tcurl", streamurl)
        rtmp_prop = append_rtmp_prop(rtmp_prop,
            "rtmp_pageurl", json.page_url)
        rtmp_prop = append_rtmp_prop(rtmp_prop,
            "rtmp_playpath", json.play_path)
        rtmp_prop = append_rtmp_prop(rtmp_prop,
            "rtmp_swfverify", json.player_url)
        rtmp_prop = append_rtmp_prop(rtmp_prop,
            "rtmp_swfurl", json.player_url)
        rtmp_prop = append_rtmp_prop(rtmp_prop,
            "rtmp_app", json.app)

        mp.set_property("file-local-options/stream-lavf-o", rtmp_prop)
    end
end

mp.add_hook(o.try_ytdl_first and "on_load" or "on_load_fail", 10, function ()
    local url = mp.get_property("stream-open-filename")
    local start_time = os.clock()
    if (url:find("ytdl://") == 1) or
        ((url:find("https?://") == 1) and not is_blacklisted(url)) then

        -- check for youtube-dl in mpv's config dir
        if not (ytdl.searched) then
            local exesuf = (package.config:sub(1,1) == '\\') and '.exe' or ''
            local ytdl_mcd = mp.find_config_file("youtube-dl" .. exesuf)
            if not (ytdl_mcd == nil) then
                msg.verbose("found youtube-dl at: " .. ytdl_mcd)
                ytdl.path = ytdl_mcd
            end
            ytdl.searched = true
        end

        -- strip ytdl://
        if (url:find("ytdl://") == 1) then
            url = url:sub(8)
        end

        local format = mp.get_property("options/ytdl-format")
        local raw_options = mp.get_property_native("options/ytdl-raw-options")
        local allsubs = true

        local command = {
            ytdl.path, "--no-warnings", "-J", "--flat-playlist",
            "--sub-format", "ass/srt/best", "--no-playlist"
        }

        -- Checks if video option is "no", change format accordingly,
        -- but only if user didn't explicitly set one
        if (mp.get_property("options/vid") == "no")
            and not option_was_set("ytdl-format") then

            format = "bestaudio/best"
            msg.verbose("Video disabled. Only using audio")
        end

        if (format == "") then
            format = "bestvideo+bestaudio/best"
        end
        table.insert(command, "--format")
        table.insert(command, format)

        for param, arg in pairs(raw_options) do
            table.insert(command, "--" .. param)
            if (arg ~= "") then
                table.insert(command, arg)
            end
            if (param == "sub-lang") and (arg ~= "") then
                allsubs = false
            end
        end

        if (allsubs == true) then
            table.insert(command, "--all-subs")
        end
        table.insert(command, "--")
        table.insert(command, url)
        msg.debug("Running: " .. table.concat(command,' '))
        local es, json, result = exec(command)

        if (es < 0) or (json == nil) or (json == "") then
            local err = "youtube-dl failed: "
            if result.error and result.error == "init" then
                err = err .. "not found or not enough permissions"
            elseif not result.killed_by_us then
                err = err .. "unexpected error ocurred"
            else
                err = string.format("%s returned '%d'", err, es)
            end
            msg.error(err)
            return
        end

        local json, err = utils.parse_json(json)

        if (json == nil) then
            msg.error("failed to parse JSON data: " .. err)
            return
        end

        msg.verbose("youtube-dl succeeded!")
        msg.debug('ytdl parsing took '..os.clock()-start_time..' seconds')

        -- what did we get?
        if not (json["direct"] == nil) and (json["direct"] == true) then
            -- direct URL, nothing to do
            msg.verbose("Got direct URL")
            return
        elseif not (json["_type"] == nil)
            and ((json["_type"] == "playlist")
            or (json["_type"] == "multi_video")) then
            -- a playlist

            if (#json.entries == 0) then
                msg.warn("Got empty playlist, nothing to play.")
                return
            end

            local self_redirecting_url =
                json.entries[1]["_type"] ~= "url_transparent" and
                json.entries[1]["webpage_url"] and
                json.entries[1]["webpage_url"] == json["webpage_url"]


            -- some funky guessing to detect multi-arc videos
            if self_redirecting_url and #json.entries > 1
                and json.entries[1].protocol == "m3u8_native"
                and json.entries[1].url then
                msg.verbose("multi-arc video detected, building EDL")

                local playlist = edl_track_joined(json.entries)

                msg.debug("EDL: " .. playlist)

                -- can't change the http headers for each entry, so use the 1st
                if json.entries[1] then
                    set_http_headers(json.entries[1].http_headers)
                end

                mp.set_property("stream-open-filename", playlist)
                if not (json.title == nil) then
                    mp.set_property("file-local-options/force-media-title",
                        json.title)
                end

                -- there might not be subs for the first segment
                local entry_wsubs = nil
                for i, entry in pairs(json.entries) do
                    if not (entry.requested_subtitles == nil) then
                        entry_wsubs = i
                        break
                    end
                end

                if not (entry_wsubs == nil) and
                    not (json.entries[entry_wsubs].duration == nil) then
                    for j, req in pairs(json.entries[entry_wsubs].requested_subtitles) do
                        local subfile = "edl://"
                        for i, entry in pairs(json.entries) do
                            if not (entry.requested_subtitles == nil) and
                                not (entry.requested_subtitles[j] == nil) then
                                subfile = subfile..edl_escape(entry.requested_subtitles[j].url)
                            else
                                subfile = subfile..edl_escape("memory://WEBVTT")
                            end
                            subfile = subfile..",length="..entry.duration..";"
                        end
                        msg.debug(j.." sub EDL: "..subfile)
                        mp.commandv("sub-add", subfile, "auto", req.ext, j)
                    end
                end

            elseif self_redirecting_url and #json.entries == 1 then
                msg.verbose("Playlist with single entry detected.")
                add_single_video(json.entries[1])
            else
                local playlist = {"#EXTM3U"}
                for i, entry in pairs(json.entries) do
                    local site = entry.url
                    local title = entry.title

                    if not (title == nil) then
                        title = string.gsub(title, '%s+', ' ')
                        table.insert(playlist, "#EXTINF:0," .. title)
                    end

                    --[[ some extractors will still return the full info for
                         all clips in the playlist and the URL will point
                         directly to the file in that case, which we don't
                         want so get the webpage URL instead, which is what
                         we want, but only if we aren't going to trigger an
                         infinite loop
                    --]]
                    if entry["webpage_url"] and not self_redirecting_url then
                        site = entry["webpage_url"]
                    end

                    if not (site:find("https?://") == 1) then
                        site = "ytdl://" .. site
                    end
                    table.insert(playlist, site)

                end

                mp.set_property("stream-open-filename", "memory://" .. table.concat(playlist, "\n"))
            end

        else -- probably a video
            add_single_video(json)
        end
    end
    msg.debug('script running time: '..os.clock()-start_time..' seconds')
end)


mp.add_hook("on_preloaded", 10, function ()
    if next(chapter_list) ~= nil then
        msg.verbose("Setting chapters")

        mp.set_property_native("chapter-list", chapter_list)
        chapter_list = {}
    end
end)


Fixed version (ground truth):
local utils = require 'mp.utils'
local msg = require 'mp.msg'
local options = require 'mp.options'

local o = {
    exclude = "",
    try_ytdl_first = false
}
options.read_options(o)

local ytdl = {
    path = "youtube-dl",
    searched = false,
    blacklisted = {}
}

local chapter_list = {}

function Set (t)
    local set = {}
    for _, v in pairs(t) do set[v] = true end
    return set
end

local safe_protos = Set {
    "http", "https", "ftp", "ftps",
    "rtmp", "rtmps", "rtmpe", "rtmpt", "rtmpts", "rtmpte",
    "data"
}

local function exec(args)
    local ret = utils.subprocess({args = args})
    return ret.status, ret.stdout, ret
end

-- return true if it was explicitly set on the command line
local function option_was_set(name)
    return mp.get_property_bool("option-info/" ..name.. "/set-from-commandline",
                                false)
end

-- return true if the option was set locally
local function option_was_set_locally(name)
    return mp.get_property_bool("option-info/" ..name.. "/set-locally", false)
end

-- youtube-dl may set special http headers for some sites (user-agent, cookies)
local function set_http_headers(http_headers)
    if not http_headers then
        return
    end
    local headers = {}
    local useragent = http_headers["User-Agent"]
    if useragent and not option_was_set("user-agent") then
        mp.set_property("file-local-options/user-agent", useragent)
    end
    local additional_fields = {"Cookie", "Referer", "X-Forwarded-For"}
    for idx, item in pairs(additional_fields) do
        local field_value = http_headers[item]
        if field_value then
            headers[#headers + 1] = item .. ": " .. field_value
        end
    end
    if #headers > 0 and not option_was_set("http-header-fields") then
        mp.set_property_native("file-local-options/http-header-fields", headers)
    end
end

local function append_rtmp_prop(props, name, value)
    if not name or not value then
        return props
    end

    if props and props ~= "" then
        props = props..","
    else
        props = ""
    end

    return props..name.."=\""..value.."\""
end

local function edl_escape(url)
    return "%" .. string.len(url) .. "%" .. url
end

local function time_to_secs(time_string)
    local ret

    local a, b, c = time_string:match("(%d+):(%d%d?):(%d%d)")
    if a ~= nil then
        ret = (a*3600 + b*60 + c)
    else
        a, b = time_string:match("(%d%d?):(%d%d)")
        if a ~= nil then
            ret = (a*60 + b)
        end
    end

    return ret
end

local function extract_chapters(data, video_length)
    local ret = {}

    for line in data:gmatch("[^\r\n]+") do
        local time = time_to_secs(line)
        if time and (time < video_length) then
            table.insert(ret, {time = time, title = line})
        end
    end
    table.sort(ret, function(a, b) return a.time < b.time end)
    return ret
end

local function is_blacklisted(url)
    if o.exclude == "" then return false end
    if #ytdl.blacklisted == 0 then
        local joined = o.exclude
        while joined:match('%|?[^|]+') do
            local _, e, substring = joined:find('%|?([^|]+)')
            table.insert(ytdl.blacklisted, substring)
            joined = joined:sub(e+1)
        end
    end
    if #ytdl.blacklisted > 0 then
        url = url:match('https?://(.+)')
        for _, exclude in ipairs(ytdl.blacklisted) do
            if url:match(exclude) then
                msg.verbose('URL matches excluded substring. Skipping.')
                return true
            end
        end
    end
    return false
end

local function make_absolute_url(base_url, url)
    if url:find("https?://") == 1 then return url end

    local proto, domain, rest =
        base_url:match("(https?://)([^/]+/)(.*)/?")
    local segs = {}
    rest:gsub("([^/]+)", function(c) table.insert(segs, c) end)
    url:gsub("([^/]+)", function(c) table.insert(segs, c) end)
    local resolved_url = {}
    for i, v in ipairs(segs) do
        if v == ".." then
            table.remove(resolved_url)
        elseif v ~= "." then
            table.insert(resolved_url, v)
        end
    end
    return proto .. domain ..
        table.concat(resolved_url, "/")
end

local function join_url(base_url, fragment)
    local res = ""
    if base_url and fragment.path then
        res = make_absolute_url(base_url, fragment.path)
    elseif fragment.url then
        res = fragment.url
    end
    return res
end

local function edl_track_joined(fragments, protocol, is_live, base)
    if not (type(fragments) == "table") or not fragments[1] then
        msg.debug("No fragments to join into EDL")
        return nil
    end

    local edl = "edl://"
    local offset = 1
    local parts = {}

    if (protocol == "http_dash_segments") and
        not fragments[1].duration and not is_live then
        -- assume MP4 DASH initialization segment
        table.insert(parts,
            "!mp4_dash,init=" .. edl_escape(join_url(base, fragments[1])))
        offset = 2

        -- Check remaining fragments for duration;
        -- if not available in all, give up.
        for i = offset, #fragments do
            if not fragments[i].duration then
                msg.error("EDL doesn't support fragments" ..
                         "without duration with MP4 DASH")
                return nil
            end
        end
    end

    for i = offset, #fragments do
        local fragment = fragments[i]
        if not url_is_safe(join_url(base, fragment)) then
            return nil
        end
        table.insert(parts, edl_escape(join_url(base, fragment)))
        if fragment.duration then
            parts[#parts] =
                parts[#parts] .. ",length="..fragment.duration
        end
    end
    return edl .. table.concat(parts, ";") .. ";"
end

local function has_native_dash_demuxer()
    local demuxers = mp.get_property_native("demuxer-lavf-list")
    for _,v in ipairs(demuxers) do
        if v == "dash" then
            return true
        end
    end
    return false
end

local function proto_is_dash(json)
    local reqfmts = json["requested_formats"]
    return (reqfmts ~= nil and reqfmts[1]["protocol"] == "http_dash_segments")
           or json["protocol"] == "http_dash_segments"
end

local function url_is_safe(url)
    local proto = type(url) == "string" and url:match("^(.+)://") or nil
    local safe = proto and safe_protos[proto]
    if not safe then
        msg.error(("Ignoring potentially unsafe url: '%s'"):format(url))
    end
    return safe
end

local function add_single_video(json)
    local streamurl = ""
    local max_bitrate = 0

    if has_native_dash_demuxer() and proto_is_dash(json) then
        local mpd_url = json["requested_formats"][1]["manifest_url"] or
            json["manifest_url"]
        if not mpd_url then
            msg.error("No manifest URL found in JSON data.")
            return
        elseif not url_is_safe(mpd_url) then
            return
        end

        streamurl = mpd_url

        if json.requested_formats then
            for _, track in pairs(json.requested_formats) do
                max_bitrate = track.tbr > max_bitrate and
                    track.tbr or max_bitrate
            end
        elseif json.tbr then
            max_bitrate = json.tbr > max_bitrate and json.tbr or max_bitrate
        end

    -- DASH/split tracks
    elseif not (json["requested_formats"] == nil) then
        for _, track in pairs(json.requested_formats) do
            local edl_track = nil
            edl_track = edl_track_joined(track.fragments,
                track.protocol, json.is_live,
                track.fragment_base_url)
            local url = edl_track or track.url
            if not url_is_safe(url) then
                return
            end
            if track.acodec and track.acodec ~= "none" then
                -- audio track
                mp.commandv("audio-add",
                    url, "auto",
                    track.format_note or "")
            elseif track.vcodec and track.vcodec ~= "none" then
                -- video track
                streamurl = url
            end
        end

    elseif not (json.url == nil) then
        local edl_track = nil
        edl_track = edl_track_joined(json.fragments, json.protocol,
            json.is_live, json.fragment_base_url)

        -- normal video or single track
        streamurl = edl_track or json.url
        set_http_headers(json.http_headers)
    else
        msg.error("No URL found in JSON data.")
        return
    end

    msg.debug("streamurl: " .. streamurl)

    streamurl = streamurl:gsub("^data:", "data://", 1)

    if not url_is_safe(streamurl) then
        return
    end

    mp.set_property("stream-open-filename", streamurl)

    mp.set_property("file-local-options/force-media-title", json.title)

    -- set hls-bitrate for dash track selection
    if max_bitrate > 0 and
        not option_was_set("hls-bitrate") and
        not option_was_set_locally("hls-bitrate") then
        mp.set_property_native('file-local-options/hls-bitrate', max_bitrate*1000)
    end

    -- add subtitles
    if not (json.requested_subtitles == nil) then
        for lang, sub_info in pairs(json.requested_subtitles) do
            msg.verbose("adding subtitle ["..lang.."]")

            local sub = nil

            if not (sub_info.data == nil) then
                sub = "memory://"..sub_info.data
            elseif not (sub_info.url == nil) then
                sub = sub_info.url
            end

            if not (sub == nil) then
                mp.commandv("sub-add", sub,
                    "auto", sub_info.ext, lang)
            else
                msg.verbose("No subtitle data/url for ["..lang.."]")
            end
        end
    end

    -- add chapters
    if json.chapters then
        msg.debug("Adding pre-parsed chapters")
        for i = 1, #json.chapters do
            local chapter = json.chapters[i]
            local title = chapter.title or ""
            if title == "" then
                title = string.format('Chapter %02d', i)
            end
            table.insert(chapter_list, {time=chapter.start_time, title=title})
        end
    elseif not (json.description == nil) and not (json.duration == nil) then
        chapter_list = extract_chapters(json.description, json.duration)
    end

    -- set start time
    if not (json.start_time == nil) and
        not option_was_set("start") and
        not option_was_set_locally("start") then
        msg.debug("Setting start to: " .. json.start_time .. " secs")
        mp.set_property("file-local-options/start", json.start_time)
    end

    -- set aspect ratio for anamorphic video
    if not (json.stretched_ratio == nil) and
        not option_was_set("video-aspect") then
        mp.set_property('file-local-options/video-aspect', json.stretched_ratio)
    end

    -- for rtmp
    if (json.protocol == "rtmp") then
        local rtmp_prop = append_rtmp_prop(nil,
            "rtmp_tcurl", streamurl)
        rtmp_prop = append_rtmp_prop(rtmp_prop,
            "rtmp_pageurl", json.page_url)
        rtmp_prop = append_rtmp_prop(rtmp_prop,
            "rtmp_playpath", json.play_path)
        rtmp_prop = append_rtmp_prop(rtmp_prop,
            "rtmp_swfverify", json.player_url)
        rtmp_prop = append_rtmp_prop(rtmp_prop,
            "rtmp_swfurl", json.player_url)
        rtmp_prop = append_rtmp_prop(rtmp_prop,
            "rtmp_app", json.app)

        mp.set_property("file-local-options/stream-lavf-o", rtmp_prop)
    end
end

mp.add_hook(o.try_ytdl_first and "on_load" or "on_load_fail", 10, function ()
    local url = mp.get_property("stream-open-filename")
    local start_time = os.clock()
    if (url:find("ytdl://") == 1) or
        ((url:find("https?://") == 1) and not is_blacklisted(url)) then

        -- check for youtube-dl in mpv's config dir
        if not (ytdl.searched) then
            local exesuf = (package.config:sub(1,1) == '\\') and '.exe' or ''
            local ytdl_mcd = mp.find_config_file("youtube-dl" .. exesuf)
            if not (ytdl_mcd == nil) then
                msg.verbose("found youtube-dl at: " .. ytdl_mcd)
                ytdl.path = ytdl_mcd
            end
            ytdl.searched = true
        end

        -- strip ytdl://
        if (url:find("ytdl://") == 1) then
            url = url:sub(8)
        end

        local format = mp.get_property("options/ytdl-format")
        local raw_options = mp.get_property_native("options/ytdl-raw-options")
        local allsubs = true

        local command = {
            ytdl.path, "--no-warnings", "-J", "--flat-playlist",
            "--sub-format", "ass/srt/best", "--no-playlist"
        }

        -- Checks if video option is "no", change format accordingly,
        -- but only if user didn't explicitly set one
        if (mp.get_property("options/vid") == "no")
            and not option_was_set("ytdl-format") then

            format = "bestaudio/best"
            msg.verbose("Video disabled. Only using audio")
        end

        if (format == "") then
            format = "bestvideo+bestaudio/best"
        end
        table.insert(command, "--format")
        table.insert(command, format)

        for param, arg in pairs(raw_options) do
            table.insert(command, "--" .. param)
            if (arg ~= "") then
                table.insert(command, arg)
            end
            if (param == "sub-lang") and (arg ~= "") then
                allsubs = false
            end
        end

        if (allsubs == true) then
            table.insert(command, "--all-subs")
        end
        table.insert(command, "--")
        table.insert(command, url)
        msg.debug("Running: " .. table.concat(command,' '))
        local es, json, result = exec(command)

        if (es < 0) or (json == nil) or (json == "") then
            local err = "youtube-dl failed: "
            if result.error and result.error == "init" then
                err = err .. "not found or not enough permissions"
            elseif not result.killed_by_us then
                err = err .. "unexpected error ocurred"
            else
                err = string.format("%s returned '%d'", err, es)
            end
            msg.error(err)
            return
        end

        local json, err = utils.parse_json(json)

        if (json == nil) then
            msg.error("failed to parse JSON data: " .. err)
            return
        end

        msg.verbose("youtube-dl succeeded!")
        msg.debug('ytdl parsing took '..os.clock()-start_time..' seconds')

        -- what did we get?
        if not (json["direct"] == nil) and (json["direct"] == true) then
            -- direct URL, nothing to do
            msg.verbose("Got direct URL")
            return
        elseif not (json["_type"] == nil)
            and ((json["_type"] == "playlist")
            or (json["_type"] == "multi_video")) then
            -- a playlist

            if (#json.entries == 0) then
                msg.warn("Got empty playlist, nothing to play.")
                return
            end

            local self_redirecting_url =
                json.entries[1]["_type"] ~= "url_transparent" and
                json.entries[1]["webpage_url"] and
                json.entries[1]["webpage_url"] == json["webpage_url"]


            -- some funky guessing to detect multi-arc videos
            if self_redirecting_url and #json.entries > 1
                and json.entries[1].protocol == "m3u8_native"
                and json.entries[1].url then
                msg.verbose("multi-arc video detected, building EDL")

                local playlist = edl_track_joined(json.entries)

                msg.debug("EDL: " .. playlist)

                -- can't change the http headers for each entry, so use the 1st
                if json.entries[1] then
                    set_http_headers(json.entries[1].http_headers)
                end

                mp.set_property("stream-open-filename", playlist)
                if not (json.title == nil) then
                    mp.set_property("file-local-options/force-media-title",
                        json.title)
                end

                -- there might not be subs for the first segment
                local entry_wsubs = nil
                for i, entry in pairs(json.entries) do
                    if not (entry.requested_subtitles == nil) then
                        entry_wsubs = i
                        break
                    end
                end

                if not (entry_wsubs == nil) and
                    not (json.entries[entry_wsubs].duration == nil) then
                    for j, req in pairs(json.entries[entry_wsubs].requested_subtitles) do
                        local subfile = "edl://"
                        for i, entry in pairs(json.entries) do
                            if not (entry.requested_subtitles == nil) and
                                not (entry.requested_subtitles[j] == nil) then
                                subfile = subfile..edl_escape(entry.requested_subtitles[j].url)
                            else
                                subfile = subfile..edl_escape("memory://WEBVTT")
                            end
                            subfile = subfile..",length="..entry.duration..";"
                        end
                        msg.debug(j.." sub EDL: "..subfile)
                        mp.commandv("sub-add", subfile, "auto", req.ext, j)
                    end
                end

            elseif self_redirecting_url and #json.entries == 1 then
                msg.verbose("Playlist with single entry detected.")
                add_single_video(json.entries[1])
            else
                local playlist = {"#EXTM3U"}
                for i, entry in pairs(json.entries) do
                    local site = entry.url
                    local title = entry.title

                    if not (title == nil) then
                        title = string.gsub(title, '%s+', ' ')
                        table.insert(playlist, "#EXTINF:0," .. title)
                    end

                    --[[ some extractors will still return the full info for
                         all clips in the playlist and the URL will point
                         directly to the file in that case, which we don't
                         want so get the webpage URL instead, which is what
                         we want, but only if we aren't going to trigger an
                         infinite loop
                    --]]
                    if entry["webpage_url"] and not self_redirecting_url then
                        site = entry["webpage_url"]
                    end

                    -- links with only youtube id as returned by --flat-playlist
                    if not site:find("://") then
                        table.insert(playlist, "ytdl://" .. site)
                    elseif url_is_safe(site) then
                        table.insert(playlist, site)
                    end

                end

                if #playlist > 0 then
                    mp.set_property("stream-open-filename", "memory://" .. table.concat(playlist, "\n"))
                end
            end

        else -- probably a video
            add_single_video(json)
        end
    end
    msg.debug('script running time: '..os.clock()-start_time..' seconds')
end)


mp.add_hook("on_preloaded", 10, function ()
    if next(chapter_list) ~= nil then
        msg.verbose("Setting chapters")

        mp.set_property_native("chapter-list", chapter_list)
        chapter_list = {}
    end
end)