Source

File: wp-includes/embed.php

function wp_embed_defaults( $url = '' ) {
	if ( ! empty( $GLOBALS['content_width'] ) ) {
		$width = (int) $GLOBALS['content_width'];
	}

	if ( empty( $width ) ) {
		$width = 500;
	}

	$height = min( ceil( $width * 1.5 ), 1000 );

	/**
	 * Filters the default array of embed dimensions.
	 *
	 * @since 2.9.0
	 *
	 * @param array  $size {
	 *     Indexed array of the embed width and height in pixels.
	 *
	 *     @type int $0 The embed width.
	 *     @type int $1 The embed height.
	 * }
	 * @param string $url  The URL that should be embedded.
	 */
	return apply_filters( 'embed_defaults', compact( 'width', 'height' ), $url );
}