About default track selection

[Seungha Yang]

Hello all

I have a question about default track selection on playbin.
Defined GstStreamFlags API includes GST_STREAM_FLAG_{SELECT, UNSELECT}.
The description is saying that, the flags indicate which track should be
default track and should not, respectively.
However, nobody check them, but they were set in qtdemux and matroska-demux.
In that context, my question is that,
- Should application check them for default track selection?
- Or, should playbin (or more child layer such as 
inputselector/decodebin) do? (but not implemented yet)


Thanks
Seungha Yang