playbin: detect if video-sink supports deinterlacing
Submitted by Matthieu Bouron
The idea here is to make playbin able to detect if the video-sink supports deinterlacing and insert whether or not the deinterlace element (and its relative bin). This should improve the situation of hardware decoders vs interlaced content when the decoder does not do the deinterlacing himself.
Two solutions have been proposed:
introduce a deinterlace interface, and implement it in the sink. The interface can add the possibility to choose a particular deinterlacing method from what the element supports.
use the element Klass, but there is no convention yet to do something like Video/Sink + Filter/Effect/Video/Deinterlace. Maybe Video/Sink/[Filter list ...] ?
The main issue I see here is, if overlaying is required (thinking about subtitles), it should only be done after deinterlacing, so the sink might also need the overlay feature if we don't insert the deinterlace element.