Error when overriding only some audio shortcode HTML output

Question

Context

I have a function that overrides audio shortcode HTML rendering, thanks to a WordPress hook:

wp_audio_shortcode_override

I used it this way in an OOP plugin:

add_filter( 'wp_audio_shortcode_override' , array( $this, 'wp_audio_shortcode_override' ), 10, 2 );

In order to prevent all the HTML shortcodes from being overridden, I want to create a custom shortcode attribute:

player="default"

As far I can read from the docs and the source code, if I return an empty string '', the override should be off. So I wrote this at the beginning of my render function:

public function wp_audio_shortcode_override( $html, $attr ) {

    $html = ''; // This is the value to disable the shortcode override

    if ( isset( $attr['player'] ) ) {
        if( $attr['player'] === 'default' )
            var_dump( $html );
            return $html;
    } 
    // After that, some code to fill the $html with thing to render,
    //   according to the shortcode attributes values

The next part of the function is how the shortcode must be overridden.

Results

• Shortcode override without conditions works
• Adding the condition in the function, and write the corresponding shortcode attribute player="default" in one audio shortcode, works.
• Adding the same shortcode attribute value to all audio shortcodes in a post works.
• Having audio shortcodes with the attribute and some without on the same post doesn't work.

Reproduce

For this, I started from a plugin example posted here: Is it possible to control the width of the Wordpress audio player?

Assistance

What did I miss? Why can I disable the override on all shortcodes, but not selectively on the same post?

Answer 1

This should work, regardless how many [audio] tags you have in the post, and regardless which have whatever attributes. My guesses are either the logic in your handler is slightly off, or a 3rd party (i.e. plugin) is hijacking the default shortcode handler behaviour.

To test, remove your code and try the following - it should clearly demonstrate if (or if not) the default shortcode & filter is working as expected:

function wpse_209708_debug_audio_shortcode( $html, $attr ) {
    if ( ! empty( $attr['player'] ) && $attr['player'] === 'default' )
        $html = '{audio player:default}';
    else
        $html = '{audio player:other}';

    return "<p>$html</p>";
}

add_filter( 'wp_audio_shortcode_override', 'wpse_209708_debug_audio_shortcode', 10, 2 );

Report back and I will update this with a "real" answer.