macosx: display total playlist duration (close #9852)
transcode: add comments on why we check frame dropping on 2 places
httplive: use longest segment to calculate reload wait instead of given max duration tag

This way if playlist contains way shorter segments than max-duration,
we have better estimate on how ofter we should reload playlist.
transcode: update 'input pts' on loop so duplicate calculation can work properly with yadif2x etc

'input pts' is the pts after all the filters, so for example yadif2x etc need to take into account.
It is used to determinate if we need to duplicate current block until we should get new picture
to encode.