Caps negotiation when there are multiple src pads

[jackBuffington]

I'll answer my own question and ask a new one since I have received no reply. 
I have partially figured out what to do and hopefully this will help someone
in the future.

It appears that GstBaseTransform only will facilitate negotiating caps for
the src and sink pads.  You are on your own for anything else.  In my case,
I did the following:

In the set_caps function I faked my own negotiation by copying the final
caps of the src pad.  In my case, this will work because I have them
connected to the same things.  I did this by:

I called gst_query_caps using the src pad to get the caps on that pad.
I used gst_set_caps on my other source pad(s) using the caps from the last
step.
I call gst_pad_query_accept_caps for my other source pad(s) to see if the
connecting pad can accept those caps (I know they can but put this in
because I eventually want to do a full negotiation)
I then use gst_pad_push_event on my other source pad(s) with
gst_event_new_caps and the caps which I want the connecting pad to use.  
I'm not certain if this step is necessary but I then called
gst_pad_set_active for the pad for my other source pads.   

At each step I am doing checks to make sure that things go OK.  

This allows things to connect up and I can see when I graph out my pipeline
that the caps are indeed properly 'negotiated'.

OK.   So everything works now right?   Unfortunately not.  I'm stuck again. 
If I connect to just one of the pads and code my chain function so that it
pushes to just that pad, I get video passing through just fine.  If I
connect to two pads and push to either pad, it will push one buffer and then
forever hang.   If I hit Control+C to kill the pipeline then it will
continue on to the next line of code which is my check to see what the
return value of the push was.  It is returning GST_FLOW_FLUSHING, which is
typically what I see when I kill the pipeline if I am running with only one
pad connected.     

So my new question is now that I am SO close to being done with this (I
think) how do I just get it to not hang on the push?





--
Sent from: http://gstreamer-devel.966125.n4.nabble.com/