When controllable is TRUE, this function ensures that future calls to gst_poll_wait() will be affected by gst_poll_restart() and gst_poll_set_flushing().
new controllable state.
TRUE if the controllability of set could be updated.
See Implementation
When controllable is TRUE, this function ensures that future calls to gst_poll_wait() will be affected by gst_poll_restart() and gst_poll_set_flushing().