thumbnailer (screenshot-mosaic) by chatgpt

thumbnailer.lua

-- thumbnailer.lua
-- Windows版：生成 x*y 缩略图，左上角写入视频信息
-- 输出到 ~~/screenshots/ （通常就是 portable_config 下对应目录）
-- input.conf可以Ctrl+Shift+s script-binding thumbnailer/generate_thumbnails
-- 依赖：ffmpeg

local mp = require("mp")
local utils = require("mp.utils")
local msg = require("mp.msg")

local options = {
    grid_cols = 4,
    grid_rows = 4,
    thumb_width = 360,
    padding_top = 250,        -- 给标题区留更大空间，避免和缩略图重叠
    font_size_header = 20,    -- 标题字体
    font_size_timestamp = 20, -- 时间戳字体
    output_dir = "~~/screenshots/",
    format = "webp",          -- "jpeg", "jxl" 或 "webp"  <-- 【修改点1：更新注释】

    skip_start_sec = 15,       -- 跳过开头黑屏/片头
    skip_end_sec = 15,         -- 顺手跳过结尾几秒，防止片尾黑屏
}

local overlay = mp.create_osd_overlay("ass-events")

local function set_loading_indicator(show)
    if show then
        overlay.res_x = 1920
        overlay.res_y = 1080
        overlay.data = "{\\an9\\pos(1900,20)\\fs60\\1c&HFFFFFF&\\bord2\\3c&H000000&}●"
        overlay:update()
    else
        overlay:remove()
    end
end

local function format_time(seconds)
    if not seconds or seconds <= 0 then
        return "00:00:00"
    end
    local h = math.floor(seconds / 3600)
    local m = math.floor((seconds % 3600) / 60)
    local s = math.floor(seconds % 60)
    return string.format("%02d:%02d:%02d", h, m, s)
end

local function format_bytes(bytes)
    if not bytes or bytes <= 0 then
        return "Unknown"
    end
    if bytes >= 1024 * 1024 * 1024 then
        return string.format("%.2f GB (%d bytes)", bytes / (1024 * 1024 * 1024), bytes)
    elseif bytes >= 1024 * 1024 then
        return string.format("%.2f MB (%d bytes)", bytes / (1024 * 1024), bytes)
    elseif bytes >= 1024 then
        return string.format("%.2f KB (%d bytes)", bytes / 1024, bytes)
    end
    return string.format("%d bytes", bytes)
end

local function format_bitrate(bps)
    if not bps or bps <= 0 then
        return "Unknown"
    end
    if bps >= 1000 * 1000 then
        return string.format("%.2f Mbps", bps / 1000 / 1000)
    end
    return string.format("%.0f kbps", bps / 1000)
end

local function is_url(path)
    return type(path) == "string" and path:match("^%a[%w+%.%-]*://") ~= nil
end

local function sanitize_filename(name)
    name = name or "video"
    name = name:gsub("%.[^.]+$", "")
    name = name:gsub('[<>:"/\\|%?%*%c]', "_")
    name = name:gsub("^%s+", ""):gsub("%s+$", "")
    if name == "" then
        name = "video"
    end
    return name
end

local function ensure_dir_exists(dir)
    local fi = utils.file_info(dir)
    if fi and fi.is_dir then
        return true
    end

    local result = mp.command_native({
        name = "subprocess",
        args = { "cmd", "/c", "mkdir", dir },
        playback_only = false,
        capture_stdout = true,
        capture_stderr = true,
    })

    local fi_after = utils.file_info(dir)
    if fi_after and fi_after.is_dir then
        return true
    end

    return false, (result and result.stderr) or "failed to create directory"
end

local function write_text_file(path, text)
    local f, err = io.open(path, "wb")
    if not f then
        return nil, err
    end
    f:write(text)
    f:close()
    return true
end

local function escape_ffmpeg_filter_value(s)
    s = s:gsub("\\", "/")
    s = s:gsub(":", "\\:")
    s = s:gsub("'", "\\'")
    s = s:gsub("%[", "\\[")
    s = s:gsub("%]", "\\]")
    s = s:gsub(",", "\\,")
    s = s:gsub(";", "\\;")
    return s
end

local function generate_thumbnails()
    local path = mp.get_property("path")
    if not path then
        mp.osd_message("没有可用输入。", 3)
        return
    end

    local duration = mp.get_property_number("duration", 0)
    local size = mp.get_property_number("file-size", 0)
    local width = mp.get_property_number("width", 0)
    local height = mp.get_property_number("height", 0)
    local fps = mp.get_property_number("estimated-vf-fps", 0)
    if fps <= 0 then
        fps = mp.get_property_number("container-fps", 0)
    end

    local codec = mp.get_property("video-codec", "unknown")

    -- 码率优先按“文件大小 / 时长”计算，更稳定
    local bitrate = 0
    if size > 0 and duration > 0 then
        bitrate = (size * 8) / duration
    else
        bitrate = mp.get_property_number("video-bitrate", 0)
        if bitrate <= 0 then
            bitrate = mp.get_property_number("bitrate", 0)
        end
    end

    local filename = mp.get_property("filename") or "video"
    local base_name = sanitize_filename(filename)

    local resolution_str = (width > 0 and height > 0) and string.format("%dx%d", width, height) or "Unknown"
    local fps_str = (fps > 0) and string.format("%.3f fps", fps) or "Unknown"

    local header_text = table.concat({
        "File: " .. filename,
        "Size: " .. format_bytes(size),
        "Duration: " .. format_time(duration),
        "Bitrate: " .. format_bitrate(bitrate),
        "Resolution: " .. resolution_str,
        "FPS: " .. fps_str,
        "Codec: " .. tostring(codec or "unknown"),
    }, "\n")

    local screenshot_dir = mp.command_native({ "expand-path", options.output_dir })
    if not screenshot_dir or screenshot_dir == "" then
        mp.osd_message("无法展开输出目录。", 3)
        return
    end

    local ok, dir_err = ensure_dir_exists(screenshot_dir)
    if not ok then
        mp.osd_message("创建输出目录失败: " .. tostring(dir_err), 4)
        msg.error("Failed to create output dir: " .. tostring(dir_err))
        return
    end

    -- 【修改点2：增加 webp 校验】
    local ext = string.lower(options.format)
    if ext ~= "jpeg" and ext ~= "jxl" and ext ~= "webp" then
        ext = "jpeg"
    end

    local out_file = utils.join_path(screenshot_dir, base_name .. "_thumb." .. ext)

    local temp_file = utils.join_path(
        screenshot_dir,
        base_name .. "._thumb_header_" .. os.time() .. "_" .. math.random(1000, 9999) .. ".txt"
    )

    local wrote, write_err = write_text_file(temp_file, header_text)
    if not wrote then
        mp.osd_message("写入临时标题文件失败: " .. tostring(write_err), 4)
        msg.error("Failed to write temp text file: " .. tostring(write_err))
        return
    end

    local tiles = options.grid_cols * options.grid_rows

    local start_sec = math.min(options.skip_start_sec or 0, math.max(duration - 1, 0))
    local end_sec = math.max(duration - (options.skip_end_sec or 0), start_sec + 1)
    local effective_duration = end_sec - start_sec
    if effective_duration <= 0 then
        start_sec = 0
        end_sec = duration
        effective_duration = duration
    end

    local interval = effective_duration / (tiles + 1)
    if interval <= 0 then
        interval = 1.0
    end

    local escaped_textfile = escape_ffmpeg_filter_value(temp_file)

    local vf = string.format(
        "select='gte(t\\,%f)*lte(t\\,%f)*(isnan(prev_selected_t)+gte(t-prev_selected_t\\,%f))'," ..
        "scale=%d:-2," ..
        "drawtext=fontsize=%d:fontcolor=white:box=1:boxcolor=black@0.6:" ..
        "text='%%{pts\\:hms}':x=w-tw-10:y=h-th-10," ..
        "tile=%dx%d:nb_frames=%d," ..
        "pad=width=iw:height=ih+%d:x=0:y=%d:color=black," ..
        "drawtext=expansion=none:fontsize=%d:fontcolor=white:line_spacing=4:" ..
        "textfile='%s':reload=0:x=20:y=20",
        start_sec, end_sec, interval,
        options.thumb_width,
        options.font_size_timestamp,
        options.grid_cols, options.grid_rows, tiles,
        options.padding_top, options.padding_top,
        options.font_size_header,
        escaped_textfile
    )

    local args = {
        "ffmpeg",
        "-v", "error",
        "-y",
        "-skip_frame", "nokey",
        "-i", path,
        "-map", "0:v:0",
        "-an", "-sn", "-dn",
        "-vf", vf,
        "-frames:v", "1",
    }

    -- 【修改点3：增加 webp 的 FFmpeg 编码参数】
    if ext == "jxl" then
        table.insert(args, "-c:v")
        table.insert(args, "libjxl")
    elseif ext == "webp" then
        table.insert(args, "-c:v")
        table.insert(args, "libwebp")
        table.insert(args, "-quality")
        table.insert(args, "90") -- webp 质量范围是 0-100，90 为高质量
    else
        table.insert(args, "-q:v")
        table.insert(args, "2")
    end

    table.insert(args, out_file)

    set_loading_indicator(true)
    mp.osd_message("正在生成缩略图...", 2)
    msg.info("Running FFmpeg: " .. table.concat(args, " "))

    mp.command_native_async({
        name = "subprocess",
        args = args,
        playback_only = false,
        capture_stdout = true,
        capture_stderr = true,
    }, function(success, result, error)
        set_loading_indicator(false)
        pcall(os.remove, temp_file)

        if success and result and result.status == 0 then
            mp.osd_message("缩略图已保存: " .. out_file, 3)
            msg.info("Saved: " .. out_file)
        else
            local err_text = "Unknown error"
            if result and result.stderr and result.stderr ~= "" then
                err_text = result.stderr
            elseif error and error ~= "" then
                err_text = error
            end
            mp.osd_message("生成失败，详见控制台。", 5)
            msg.error("FFmpeg Error: " .. err_text)
        end
    end)
end

mp.add_key_binding("ctrl+T", "generate_thumbnails", generate_thumbnails)