如何在php中手动添加描述和关键字？

This is my php code, and I want to add a manual description and keywords in here?

// define meta tags
$meta_title = $video['video_title'] . ' MyWebsite ';
$video['excerpt'] = (empty($video['excerpt'])) ? $video['video_title'] : $video['excerpt'];
$meta_description = generate_excerpt(str_replace('"', '"', $video['excerpt']), 150) .'...';

$meta_keywords = '';
if(is_array($tags_arr))
foreach($tags_arr as $id => $v)
{
    $meta_keywords .= $v['tag'] . ', ';
}
$meta_keywords = substr($meta_keywords, 0, -2);
// end

If you just want to concatenate your meta to existing meta like with the title, define an array of your meta and concatenate it.

<?php
$meta = [
    'title' => 'MyWebsite',
    'description' => 'My description',
    'keywords' => 'My keywords',
];

// define meta tags
$meta_title = $video['video_title'].' '.$meta['title'];
$video['excerpt'] = (empty($video['excerpt'])) ? $video['video_title'] : $video['excerpt'];
$meta_description = generate_excerpt(str_replace('"', '&quot;', $video['excerpt'].' '.$meta['description']), 150).'...';

$meta_keywords = '';
if (is_array($tags_arr)) {
    foreach ($tags_arr as $id => $v) {
        $meta_keywords .= $v['tag'] . ', ';
    }
    $meta_keywords = substr($meta_keywords, 0, -2).' '.$meta['keywords'];
}

If you want to replace the meta, then just replace the vars.

<?php
$meta = [
    'title' => 'MyWebsite',
    'description' => 'My description',
    'keywords' => 'My keywords',
];

// define meta tags
$meta_title = $video['video_title'].' '.$meta['title'];
$meta_description = $meta['description'];
$meta_keywords = $meta['keywords'];