SDP tags should be converted to TagList by the depayloader
The SDP spec rfc4566 supports the following tags:
i=<value> also called
information is the title of the media,
Attributes are already in the RTP caps as
a-lang=<lang>, so that can be directly translated to TagList by the depayloader. Not sure about the title.
Also, when we're using RTSP, we can likely also emit
GST_TAG_DURATION when playing on-demand media.