Subclasses should override this when they can provide an
alternate method of spawning a thread to drive the pipeline in pull mode.
Should start or stop the pulling thread, depending on the value of the
"active" argument. Called after actually activating the sink pad in pull
mode. The default implementation starts a task on the sink pad.
Subclasses should override this when they can provide an alternate method of spawning a thread to drive the pipeline in pull mode. Should start or stop the pulling thread, depending on the value of the "active" argument. Called after actually activating the sink pad in pull mode. The default implementation starts a task on the sink pad.