如何使输出json数组与php

我已经搜索了答案，但是没有解决我的问题。

怎么输出这样的?
提前感谢

Title: First Title
标签:标签-1，标签-2，标签-3

Title: Second Title
标签:tag-b-1, tag-b-2, tag-b-3

Title: Third Title
标签:tag-c-1, tag-c-2, tag-c-3

file.json

{
"videos": [
    {
        "title": "First Title",
        "tags": [
            {
                "tag_name": "tag-a-1"
            },
            {
                "tag_name": "tag-a-2"
            },
            {
                "tag_name": "tag-a-3"
            }
        ],
        "publish_date": "2016-09-12 16:40:14"
    },
    {
        "title": "Second Title",
        "tags": [
            {
                "tag_name": "tag-b-1"
            },
            {
                "tag_name": "tag-b-2"
            },
            {
                "tag_name": "tag-b-3"
            }
        ],
        "publish_date": "2016-09-12 16:40:14"
    },
    {
        "title": "Third Title",
        "tags": [
            {
                "tag_name": "tag-c-1"
            },
            {
                "tag_name": "tag-c-2"
            },
            {
                "tag_name": "tag-c-3"
            }
        ],
        "publish_date": "2016-09-12 16:40:14"
    }
]

}

output.php

<?php 
    ini_set('display_errors', 1);
    $html = "file.json";
    $html = file_get_contents($html);
    $videos = json_decode($html, true);
        foreach ($videos['videos'] as $video) {
            $title = $video['title'];
            foreach ($video['tags'] as $tags) {
                $tags = $tags['tag_name'];
            echo 'Title: ' . $title . '<br />';
            echo 'Tags: ' . $tags . ', <br /><br />';
            }
        } 

    foreach ($videos['videos'] as $video) {
        $title = $video['title'];
        $tags = array(); // reset it every new item to avoid race-condition on empty one.
        foreach ($video['tags'] as $tags) {
            $tags[] = $tags['tag_name'];
            //   ^ also add new elements here
        }
        echo 'Title: ' . $title . '<br />';
        echo 'Tags: ' . implode(',', $tags) . '<br /><br />';
        //              ^ also join your tags
    }