How to dynamically change webcam photo timestamps

to generate the galerie, you can put this shortcode in the file functions.php of your theme (create a child theme if the theme can be updated)

add_shortcode("webcamPictures", function ($attr, $content, $tag) {

    $picturesByLine = 5;

    $directoryBase = realpath(__DIR__ . "/../../../images");
    $urlBase = home_url("/images");


    // reading pictures

    $picturesRaw = glob("$directoryBase/{$attr["type"]}*");

    $pictures = [];


    foreach ($picturesRaw as $p) {

        $pictures[] = [
            "filename" => basename($p),
            "mtime" => filemtime($p),
        ];

    }


    // sorting

    usort($pictures, function ($p1, $p2) {
        return $p2["mtime"] - $p1["mtime"];
    });


    // display

    $firstPicture = array_shift($pictures);
    $firstPictureURL = "$urlBase/{$firstPicture["filename"]}";

    $picturesEnd = count($pictures) - 1;


    ob_start();

    ?>
        <table class=" table table-hover"
            style="table-layout: fixed; border-collapse: separate; border-spacing: 30px;">
            <tbody>
                <tr>
                    <td style="bgcolor="#EAEAEA"><a
                        href="https://wordpress.stackexchange.com/questions/285582/<?php echo esc_html($firstPictureURL);?>"><img
                            src="https://wordpress.stackexchange.com/questions/285582/<?php echo esc_html($firstPictureURL);?>"></a>
                    </td>
                </tr>
            </tbody>
        </table>
        <table class=" table table-hover"
            style="table-layout: fixed; border-collapse: separate; border-spacing: 30px;">
            <tbody>
                <tr>

                    <?php foreach ($pictures as $index => $p) {?>

                        <?php
                            $pictureURL = "$urlBase/{$p["filename"]}";
                        ?>

                        <td style="width: 20%;" bgcolor="#EAEAEA"><a
                            href="<?php echo esc_html($pictureURL);?>"><img
                                src="<?php echo esc_html($pictureURL);?>"></a>
                        </td>


                        <?php
                            if (    (0 === ($index + 1) % $picturesByLine)
                                &&  ($index !== $picturesEnd)
                            ) {
                        ?>
                            </tr><tr>
                        <?php }?>


                    <?php }?>

                </tr>

            </tbody>
        </table>


    <?php

    $content = ob_get_clean();


    return $content;

});

to use this shortcode, put this in your page content : [webcamPictures type="CGCHdCam1"]