Stop the task of pad. This function will also make sure that the function executed by the task will effectively stop if not called from the GstTaskFunction.
This function will deadlock if called from the GstTaskFunction of the task. Use Task.pause instead.
Regardless of whether the pad has a task, the stream lock is acquired and released so as to ensure that streaming through this pad has finished.
a TRUE if the task could be stopped or FALSE on error.