Struct gstreamer::Pad

source ·
#[repr(transparent)]
pub struct Pad { /* private fields */ }
Expand description

A Element is linked to other elements via “pads”, which are extremely light-weight generic link points.

Pads have a PadDirection, source pads produce data, sink pads consume data.

Pads are typically created from a PadTemplate with from_template() and are then added to a Element. This usually happens when the element is created but it can also happen dynamically based on the data that the element is processing or based on the pads that the application requests.

Pads without pad templates can be created with new(), which takes a direction and a name as an argument. If the name is None, then a guaranteed unique name will be assigned to it.

A Element creating a pad will typically use the various gst_pad_set_*_function() calls to register callbacks for events, queries or dataflow on the pads.

gst_pad_get_parent() will retrieve the Element that owns the pad.

After two pads are retrieved from an element by ElementExt::static_pad(), the pads can be linked with PadExt::link(). (For quick links, you can also use ElementExtManual::link(), which will make the obvious link for you if it’s straightforward.). Pads can be unlinked again with PadExt::unlink(). PadExt::peer() can be used to check what the pad is linked to.

Before dataflow is possible on the pads, they need to be activated with PadExt::set_active().

PadExtManual::query() and PadExtManual::peer_query() can be used to query various properties of the pad and the stream.

To send a Event on a pad, use PadExtManual::send_event() and PadExtManual::push_event(). Some events will be sticky on the pad, meaning that after they pass on the pad they can be queried later with PadExtManual::sticky_event() and PadExtManual::sticky_events_foreach(). PadExt::current_caps() and PadExt::has_current_caps() are convenience functions to query the current sticky CAPS event on a pad.

GstElements will use PadExtManual::push() and PadExtManual::pull_range() to push out or pull in a buffer.

The dataflow, events and queries that happen on a pad can be monitored with probes that can be installed with PadExtManual::add_probe(). PadExt::is_blocked() can be used to check if a block probe is installed on the pad. PadExt::is_blocking() checks if the blocking probe is currently blocking the pad. PadExtManual::remove_probe() is used to remove a previously installed probe and unblock blocking probes if any.

Pad have an offset that can be retrieved with PadExt::offset(). This offset will be applied to the running_time of all data passing over the pad. PadExt::set_offset() can be used to change the offset.

Convenience functions exist to start, pause and stop the task on a pad with PadExtManual::start_task(), PadExt::pause_task() and PadExt::stop_task() respectively.

Implements

PadExt, GstObjectExt, glib::ObjectExt, PadExtManual

Implementations

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