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 add_probe. In each of the groups, probes are called in the order in which they were added.
| this |
the Pad to add the probe to |
| mask |
the probe mask |
| callback |
PadProbeCallback that will be called with notifications of the pad state |
| destroy_data |
DestroyNotify for user_data |
| user_data |
user data passed to the callback |