# STEP 2 : Create the Gstreamer element on template

## STEP 2.1 : Build the Gstreamer template and testing

This process will build gstreamer template plugin for create your gstreamer template for get data from gstreaamer on step 3&#x20;

1. Build gstreamer on devcontainer

```bash
$ meson build
```

<figure><img src="https://paper-attachments.dropbox.com/s_8D12BA9D3ACC276FE6456B192705A16DC9CD19AC9DCDCFFA08371C99F10A1BD1_1645014929595_image.png" alt=""><figcaption></figcaption></figure>

2\. Linking library from build file&#x20;

```bash
$ ninja -C build
```

<figure><img src="https://paper-attachments.dropbox.com/s_8D12BA9D3ACC276FE6456B192705A16DC9CD19AC9DCDCFFA08371C99F10A1BD1_1645014949994_image.png" alt=""><figcaption></figcaption></figure>

3\. Set environment to built gstreamer template

```bash
$ export GST_PLUGIN_PATH=/workspaces/gst-template/build/gst-plugin
```

4\. Check gst-plugin[ _gst-inspect-1.0_](https://gstreamer.freedesktop.org/documentation/tools/gst-inspect.html?gi-language=c)[ ](https://gstreamer.freedesktop.org/documentation/tools/gst-inspect.html?gi-language=c)is a tool that prints out information on availabl _GStreamer_ plugins, information about a particular plugin, or information about a particular element.&#x20;

```bash
$ gst-inspect-1.0 /workspaces/gst-template/build/gst-plugin/libgstplugin.so
```

<figure><img src="https://paper-attachments.dropbox.com/s_8D12BA9D3ACC276FE6456B192705A16DC9CD19AC9DCDCFFA08371C99F10A1BD1_1645015371091_image.png" alt=""><figcaption></figcaption></figure>

From the inspection, we found version of gst-plugin from we build is version 1.19.0.1 and it’s gstreamer element, The name of element is **plugin\_template**

5\. Test run gst-template working&#x20;

```bash
$ gst-launch-1.0 videotestsrc ! plugin_template ! fakesink
```

<figure><img src="https://paper-attachments.dropbox.com/s_8D12BA9D3ACC276FE6456B192705A16DC9CD19AC9DCDCFFA08371C99F10A1BD1_1645016516068_image.png" alt=""><figcaption></figcaption></figure>

## STEP 2.2 : Create the gstreamer template&#x20;

In this state, we will create our gstreamer template for get data from mockup data and application gstreamer code for get more data.&#x20;

1\. First we will create the gstreamer element

```bash
$ cd gst-plugin/src
$ ../tools/make_element videodatagst 
# video_data_gst just a name of your element, Don't worry to create your element name like lnwza007.
```

<figure><img src="https://paper-attachments.dropbox.com/s_8D12BA9D3ACC276FE6456B192705A16DC9CD19AC9DCDCFFA08371C99F10A1BD1_1645016317462_image.png" alt=""><figcaption></figcaption></figure>

2\. Go to line 247 : gst videodatagst\_chain. This function using for adjust working process inside the element. What is gst elemnet please folow this [link](https://gstreamer.freedesktop.org/documentation/application-development/basics/elements.html?gi-language=c)

* The Gstreamer element is black box of video process, it’s can recive input process from sink and put throughtput to src

<figure><img src="https://paper-attachments.dropbox.com/s_8D12BA9D3ACC276FE6456B192705A16DC9CD19AC9DCDCFFA08371C99F10A1BD1_1645016720311_image.png" alt=""><figcaption></figcaption></figure>

From the function, we saw the parameter is&#x20;

* [pad](https://gstreamer.freedesktop.org/documentation/application-development/basics/pads.html?gi-language=c) are the element's interface to the outside world. Data streams from one element's source pad to another element's sink pad.
* [parent](https://gstreamer.freedesktop.org/documentation/additional/design/relations.html?gi-language=c#object-relation-types) are the element’s relation on sink or src pad between element for reference data with the group of parent element.
* [buf](https://gstreamer.freedesktop.org/documentation/gstreamer/gstbuffer.html?gi-language=c#gstbuffer-page) are the basic unit of data transfer in GStreamer. They contain the timing and offset along with other arbitrary metadata that is associated with the [GstMemory](https://gstreamer.freedesktop.org/documentation/gstreamer/gstmemory.html#GstMemory) blocks that the buffer contains.

So from this function is chain. it’s mean working process on element pad, we can debug code or define element process on this fucntion.&#x20;
