How to access featured image?

• get_the_post_thumbnail ( $post/$post_id, $sizes, $attr ) will give you the featured image as html to output.

• get_post_thumbnail_id ( get_the_ID ( ) ) will give you the ID of the featured image so you can use it to get more information. Getting the thumbnail ID is essentially accessing the the post’s meta data:

  $image_id = get_post_meta( $post->ID, '_thumbnail_id', true )

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• wp_get_attachment_metadata ( $attachment_id, $unfiltered ) will give you all the meta data associated with the image.

• wp_get_attachment_image_src( $attachment_id, $size, $icon ) will give you an array of information for a particular size.

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 [0] => url
 [1] => width
 [2] => height
 [3] => boolean: true if $url is a resized image, false if it is the original or if no image is available.

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In the above example you can get the src and id using:

$image_src  = media_sideload_image($video_thumb_url, $description, 'src');
$image_id   = attachment_url_to_postid($image_src); 
set_post_thumbnail($post_id, $image_id );