MediaElement CSS only brings in broken "legacy" css by default??

[programmin]

The mediaelementplayer-legacy.min.css mentioned in #39686 should probably include the mediaelementplayer.css as that is what actually has the css for

.mejs__time-rail, .mejs__mute

and others that mejs adds to the page (why did they change the class names??)

Otherwise the mejs player is a broken bunch of odd looking buttons.

[rafa8626]

@programmin You need to use the element classPrefix in the MediaElement.js configuration to avoid breaking things:

classPrefix: 'mejs-'

[rafa8626]

If you check wp-includes/script-loader.php file, line 453, you will see that element used for the Embed element

[programmin]

So existing themes will need to change that in configuration js somewhere to have the current 4.8 behavior?

[rafa8626]

My assumption is that, unless you are using MEJS without the Embed widget, yes, it will be required to add that flag. Otherwise, it is covered already

[programmin]

Why should I change the prefix when the default as seen on their site is prefixed mejs ? ​http://www.mediaelementjs.com/

I really think this is a bug especially since the mediaelementplayer.css included doesn't seem to be mentioned anywhere in the WP code.

[rafa8626]

Because that prefix is the one used by most of WP products; if we don't set it up we'll break a lot of code and themes. As an agreement the new code will use BEN notation but for backward compatibility the prefix must be used. It's not a bug since the intention was not to use the new style sheet for WP and at the same time provide the latest and more stable version of MEJS without disturbing a lot of things

[antpb]

This change does not seem to be impacting anymore since the changes to mediaelementjs over the last 5 years. See: ​https://make.wordpress.org/core/2017/10/30/mediaelement-upgrades-in-wordpress-4-9/

We brought this ticket up in a recent bug scrub in Media and determined that this issue should be closed and a new one should be re-opened if still impacting. From our understanding it is not and the prefix is intentional and required to ensure we do not break the experience for folks.