Selecting alternate elementary streams

[Jim Hodapp]

I am using playbin2 to construct a pipeline that, for this example, is 
using mpegtsdemux. My source program contains one video stream and 
multiple audio streams for different languages. My first question is, 
what is the intended way to be notified and extract the PMT information 
that makes up this program from playbin2? Do I need to get a pointer 
directly to the demux or is there a way that playbin2 can abstract this 
for me?

My second question is how do then select a particular audio stream to be 
used? Does playbin2 also abstract this operation?

If playbin2 does not directly provide a generic interface to do this, is 
there an interface to accomplish this that would also apply to other 
types of demuxes that support the notion of a program and elementary 
streams?

Thanks,

Jim