wp_embed_register_handler example

    if ( ! apply_filters( 'load_default_embeds', true ) ) {
        return;
    }

    wp_embed_register_handler( 'youtube_embed_url', '#https?://(www.)?youtube\.com/(?:v|embed)/([^/]+)#i', 'wp_embed_handler_youtube' );

    /** * Filters the audio embed handler callback. * * @since 3.6.0 * * @param callable $handler Audio embed handler callback function. */
    wp_embed_register_handler( 'audio', '#^https?://.+?\.(' . implode( '|', wp_get_audio_extensions() ) . ')$#i', apply_filters( 'wp_audio_embed_handler', 'wp_embed_handler_audio' ), 9999 );

    /** * Filters the video embed handler callback. * * @since 3.6.0 * * @param callable $handler Video embed handler callback function. */