the probe mask
#GstPadProbeCallback that will be called with notifications of the pad state
an id or 0 if no probe is pending. The id can be used to remove the probe with gst.pad.Pad.removeProbe. When using GST_PAD_PROBE_TYPE_IDLE it can happen that the probe can be run immediately and if the probe returns GST_PAD_PROBE_REMOVE this functions returns 0.
MT safe.
Be notified of different states of pads. The provided callback is called for every state that matches mask.
Probes are called in groups: First GST_PAD_PROBE_TYPE_BLOCK probes are called, then others, then finally GST_PAD_PROBE_TYPE_IDLE. The only exception here are GST_PAD_PROBE_TYPE_IDLE probes that are called immediately if the pad is already idle while calling gst.pad.Pad.addProbe. In each of the groups, probes are called in the order in which they were added.