mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-11-14 13:21:28 +00:00
57 lines
1.8 KiB
Markdown
57 lines
1.8 KiB
Markdown
|
---
|
||
|
|
title: Specifying the pads
|
||
|
|
...
|
||
|
|
|
||
|
|
# Specifying the pads
|
||
|
|
|
||
|
|
As explained before, pads are the port through which data goes in and
|
||
|
|
out of your element, and that makes them a very important item in the
|
||
|
|
process of element creation. In the boilerplate code, we have seen how
|
||
|
|
static pad templates take care of registering pad templates with the
|
||
|
|
element class. Here, we will see how to create actual elements, use an
|
||
|
|
`_event
|
||
|
|
()`-function to configure for a particular format and how to register
|
||
|
|
functions to let data flow through the element.
|
||
|
|
|
||
|
|
In the element `_init ()` function, you create the pad from the pad
|
||
|
|
template that has been registered with the element class in the
|
||
|
|
`_class_init ()` function. After creating the pad, you have to set a
|
||
|
|
`_chain ()` function pointer that will receive and process the input
|
||
|
|
data on the sinkpad. You can optionally also set an `_event ()` function
|
||
|
|
pointer and a `_query ()` function pointer. Alternatively, pads can also
|
||
|
|
operate in looping mode, which means that they can pull data themselves.
|
||
|
|
More on this topic later. After that, you have to register the pad with
|
||
|
|
the element. This happens like this:
|
||
|
|
|
||
|
|
```
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
static void
|
||
|
|
gst_my_filter_init (GstMyFilter *filter)
|
||
|
|
{
|
||
|
|
/* pad through which data comes in to the element */
|
||
|
|
filter->sinkpad = gst_pad_new_from_static_template (
|
||
|
|
&sink_template, "sink");
|
||
|
|
/* pads are configured here with gst_pad_set_*_function () */
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
gst_element_add_pad (GST_ELEMENT (filter), filter->sinkpad);
|
||
|
|
|
||
|
|
/* pad through which data goes out of the element */
|
||
|
|
filter->srcpad = gst_pad_new_from_static_template (
|
||
|
|
&src_template, "src");
|
||
|
|
/* pads are configured here with gst_pad_set_*_function () */
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
gst_element_add_pad (GST_ELEMENT (filter), filter->srcpad);
|
||
|
|
|
||
|
|
/* properties initial value */
|
||
|
|
filter->silent = FALSE;
|
||
|
|
}
|
||
|
|
|
||
|
|
```
|
||
|
|
|