Kindly help me convert this htaccess to nginx directives?

[ubunifu]

ErrorDocument 404 /
ErrorDocument 500 /

Options +FollowSymlinks
RewriteEngine on
RewriteBase /

<IfModule mod_security.c>
SecFilterEngine Off
SecFilterScanPOST Off
</IfModule>

RewriteCond %{SCRIPT_FILENAME} !-d
RewriteCond %{SCRIPT_FILENAME} !-f

RewriteRule ^([^\.\/\-]+)$ $1.php [L]

RewriteRule ^videos/([^\.\/]+)$ /video-file.php?id=$1 [L]
RewriteRule ^audios/([^\.\/]+)$ /audio-file.php?id=$1 [L]
RewriteRule ^notes/([^\.\/]+)$ /note-file.php?id=$1 [L]
RewriteRule ^exercises/([^\.\/]+)$ /exercise-file.php?id=$1 [L]
RewriteRule ^links/([^\.\/]+)$ /link.php?id=$1 [L]
RewriteRule ^class/([^\.\/]+)$ /class.php?slug=$1 [L]
RewriteRule ^subject/([^\.\/]+)$ /subject.php?slug=$1 [L]
RewriteRule ^author/([^\.\/]+)$ /author.php?username=$1 [L]

RewriteRule ^search/([^\.]+)$ /search.php?query=$1 [L]

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,237098,237098#msg-237098