Don't re-upload album covers that already exist

[wonderboymusic]

If I drag 5 files that have ID3 tags from the same album into the uploader...

Currently:
5 images are uploaded

What should happen:
We store a hash of the bits with the attachment and check for it before re-uploading the image

[GregLone]

Erf, I was about to post almost the same thing -_-'

The difference is I used a filter before the thumbnail creation, so plugins can add a title to the attachment if they want (track title? album title?).

/**
 * Filter the parameters for the attachment thumbnail creation.
 *
 * @since 3.9.0
 *
 * @param array $attachment An array of parameters to create the thumbnail.
 * @param array $metadata   Current attachment metadata.
 * @param array $uploaded   An array containing the thumbnail path and url.
 */
$attachment = apply_filters( 'attachment_thumbnail_args', $attachment, $metadata, $uploaded );

$sub_attachment_id = wp_insert_attachment( $attachment, $uploaded['file'] );

Also, I used a post meta to store the hash, but post_content_filtered seems to be better. Less easy to get but we won't use it every day.

[nacin]

I understand why post_content_filtered was chosen, but I don't love it here. It also isn't indexed so it's not a whole lot better than, say, a meta query.

[wonderboymusic]

27573.2.diff​ implements this by using get_posts() and a key-only meta_query. Both patches' queries are sub-millisecond. This one is probably preferable because it uses more API and no direct SQL. This code will hardly ever run, so speed arguments may be moot.

[GregLone]

What about the filter?

[GregLone]

Owned by 70 seconds... XD

Thanks @wonderboymusic

[wonderboymusic]

27573.3.diff​ 80 seconds before your comment.

[nacin]

Rather than 'meta_query' => array( array( 'key' => $hash ) ) we can use 'meta_key' => $hash. That said, I don't really like the idea of an unprefixed md5 hash meta key floating around in the metadata table. This is a situation ripe for 'meta_key' => '_album_cover_hash', 'meta_value' => $hash. Speed is not super-essential here and it is hardly the first barebones meta key/value query we do in the admin.

[wonderboymusic]

27573.4.diff​ implements _cover_hash since this also applies to video

[wonderboymusic]

In 27863:

In wp_generate_attachment_metadata(), when an audio or video files contains upload-able image bits in its ID3 tags, only upload it if the image has not already been uploaded. Determine this by checking for a _cover_hash value in post meta that matches the md5 representation of the bits.

This prevents uploading an album of 10 songs and subsequently uploading 10 copies of the same album cover.

Props GregLone for the new filter/filter docs: 'attachment_thumbnail_args'.
Fixes #27573.