PHP Warning: POST Content-Length of 1649460972 bytes exceeds the limit of 1073741824 bytes in Unknown on line 0

Recently I wrote an upload script in PHP, set the limits using .htaccess:

php_value upload_max_filesize "1.99G"
php_value post_max_size "1.99G"

and then I got this strange error:

PHP Warning: POST Content-Length of 1649460972 bytes exceeds the limit of 1073741824 bytes in Unknown on line 0

while trying to upload 1.53 GB file. But why the error said I exceeded 1GB limit?

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