Changes the default embed sizes based on conditionals

embed-objects.php

add_filter( 'embed_defaults', 'wps_embed_defaults' );
/**
 * Changes the default embed sizes based on site layout
 * @author Travis Smith
 *
 * @param array height and width keys, values can be string/int
 * @return array height and width keys and values
 */
function wps_embed_defaults( $defaults ) {  

	if ( is_home() || is_category() )
		return array( 'width'  => 600, 'height' => 400 );
	else
		return $defaults;

}