Struct gstreamer::PadTemplate

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

Padtemplates describe the possible media types a pad or an elementfactory can handle. This allows for both inspection of handled types before loading the element plugin as well as identifying pads on elements that are not yet created (request or sometimes pads).

Pad and PadTemplates have Caps attached to it to describe the media type they are capable of dealing with. caps() or GST_PAD_TEMPLATE_CAPS() are used to get the caps of a padtemplate. It’s not possible to modify the caps of a padtemplate after creation.

PadTemplates have a PadPresence property which identifies the lifetime of the pad and that can be retrieved with GST_PAD_TEMPLATE_PRESENCE(). Also the direction of the pad can be retrieved from the PadTemplate with GST_PAD_TEMPLATE_DIRECTION().

The GST_PAD_TEMPLATE_NAME_TEMPLATE () is important for GST_PAD_REQUEST pads because it has to be used as the name in the ElementExtManual::request_pad_simple() call to instantiate a pad from this template.

Padtemplates can be created with new() or with gst_static_pad_template_get (), which creates a PadTemplate from a StaticPadTemplate that can be filled with the convenient GST_STATIC_PAD_TEMPLATE() macro.

A padtemplate can be used to create a pad (see Pad::from_template() or gst_pad_new_from_static_template ()) or to add to an element class (see gst_element_class_add_static_pad_template ()).

The following code example shows the code to create a pad from a padtemplate.

⚠️ The following code is in C ⚠️

  GstStaticPadTemplate my_template =
  GST_STATIC_PAD_TEMPLATE (
    "sink",          // the name of the pad
    GST_PAD_SINK,    // the direction of the pad
    GST_PAD_ALWAYS,  // when this pad will be present
    GST_STATIC_CAPS (        // the capabilities of the padtemplate
      "audio/x-raw, "
        "channels = (int) [ 1, 6 ]"
    )
  );
  void
  my_method (void)
  {
    GstPad *pad;
    pad = gst_pad_new_from_static_template (&my_template, "sink");
    ...
  }

The following example shows you how to add the padtemplate to an element class, this is usually done in the class_init of the class:

⚠️ The following code is in C ⚠️

  static void
  my_element_class_init (GstMyElementClass *klass)
  {
    GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass);

    gst_element_class_add_static_pad_template (gstelement_class, &my_template);
  }

Implements

GstObjectExt, glib::ObjectExt

Implementations

Creates a new pad template with a name according to the given template and with the given arguments.

name_template

the name template.

direction

the PadDirection of the template.

presence

the PadPresence of the pad.

caps

a Caps set for the template.

Returns

a new PadTemplate.

Creates a new pad template with a name according to the given template and with the given arguments.

name_template

the name template.

direction

the PadDirection of the template.

presence

the PadPresence of the pad.

caps

a Caps set for the template.

pad_type

The GType of the pad to create

Returns

a new PadTemplate.

Emit the pad-created signal for this template when created by this pad.

pad

the Pad that created it

This signal is fired when an element creates a pad from this template.

pad

the pad that was created.

Converts a StaticPadTemplate into a PadTemplate with a type.

pad_template

the static pad template

pad_type

The GType of the pad to create

Returns

a new PadTemplate.

Gets the capabilities of the pad template.

Returns

the Caps of the pad template. Unref after usage.

Available on crate feature v1_18 only.

See [set_documentation_caps()][Self::set_documentation_caps()].

Returns

The caps to document. For convenience, this will return caps() when no documentation caps were set.

The direction of the pad described by the pad template.

The type of the pad described by the pad template.

The name template of the pad template.

When the pad described by the pad template will become available.

Trait Implementations

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