[TYPO3-dev] Hook into page title generation

[Philipp]

Hey, can you please give me a few hints on a very basic problem?

I need to modify the page title of my generated pages. 
Standard Scenario: page title - website title
Alternative Scenario: If subtitle is filled in: subtitle (no appendix)

and of yourse i cant just disable the title and add some headerdata, i need to overrule that title from cached content elements many times.

please give me some hints on that task, the correct Hook seems to be registered like 
$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['tslib/class.tslib_fe.php']['contentPostProc-all']