wp_get_attachment_image_src() returning incorrect width and height [duplicate]

I found the same issue here and the solution from there works: Settings in ‘Media > Settings’ is ignored when inserting images

The solution is as simple as paste this:

$content_width = 2000;// The value I want

in functions.php

Explanation copied from there(user Chip Bennett):

I believe your issue is that the value set for the global $content_width variable (which is 640px in Boilerplate and 584px in Twenty Eleven) is less than the width you’re specifying via Settings -> Media.

WordPress is overriding your user setting with the Theme-specific value. This actually makes sense, since a Theme knows its maximum content width, and using a larger image width than what the Theme is designed to accommodate would very likely break the Theme layout.