Pause and resume a sub-pipeline in C application

[Gregoire Gentil]

Hello,

I'm using in a C application the following pipeline to display and 
record a stream:
rtspsrc ! rtph264depay ! tee name=d ! queue ! ffdec_h264 ! xvimagesink 
d. ! queue ! mpegtsmux ! filesink location=/tmp/a

I would like to pause and resume the stream dump while never stopping 
the display. During runtime, I tried to change the location property of 
filesink from a file path to /dev/null but it doesn't seem to work.

Any idea how I can achieve pause & resume for a sub-pipeline? Many 
thanks in advance,

Grégoire