AVFoundation QMultimedia backend does not report duration for HTTP progressive download

When pointing QMediaPlayer at an HTTP url for progressive download of an MP3 file on OS-X or iOS the AVFoundation backend in avfmediaplayersession.mm does not report back a correct duration after buffering is complete. It reports infinity (os-x) or 0 (iOS). Having looked at the code it seems you are not observing currentItem.duration and thus no durationChanged signal with a correct duration is emitted.

Please see http://stackoverflow.com/questions/5952694/ios-avasset-duration-is-zero-for-http-live-streaming-but-works-for-progressive