WordPress filter for adding responsive wrapper to embedded content

functions.php

<?php
/**
 * Filter for adding wrappers around embedded objects
 */
function responsive_embeds( $content ) {
	$content = preg_replace( "/<object/Si", '<div class="embed-container"><object', $content );
	$content = preg_replace( "/<\/object>/Si", '</object></div>', $content );
	
	/**
	 * Added iframe filtering, iframes are bad.
	 */
	$content = preg_replace( "/<iframe.+?src=\"(.+?)\"/Si", '<div class="embed-container"><iframe src="\1" frameborder="0" allowfullscreen>', $content );
	$content = preg_replace( "/<\/iframe>/Si", '</iframe></div>', $content );

	return $content;
}

add_filter( 'the_content', 'responsive_embeds' );