# Meson devenv and Python Gst.parse\_launch( pipeline )

**URL:** https://discourse.gstreamer.org/t/meson-devenv-and-python-gst-parse-launch-pipeline/5885
**Category:** General Discussion
**Tags:** python
**Created:** [August 25, 2026, 7:58pm UTC](https://discourse.gstreamer.org/t/meson-devenv-and-python-gst-parse-launch-pipeline/5885 "2026-08-25T19:58:53Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![CarlFK](https://discourse.gstreamer.org/user_avatar/discourse.gstreamer.org/carlfk/32/1722_2.png) [@CarlFK](https://discourse.gstreamer.org/u/CarlFK)
#### Post date: [August 25, 2026, 7:58pm UTC](https://discourse.gstreamer.org/t/meson-devenv-and-python-gst-parse-launch-pipeline/5885/1 "2026-08-25T19:58:53Z")

</div>

I build gst master and:

```auto
python3 -m venv venvs/veyepar --system-site-packages
videoteam@mo:~$ meson devenv -C gstreamer/builddir
[gstreamer-full] videoteam@mo:~$ gst-launch-1.0 decklink2srcbin device-number=1 ! fakesink 

```

Works fine. good.

Then I try to use decklink2srcbin in my python app.

```auto
[gstreamer-full] videoteam@mo:~/gstreamer/builddir$ . ~/venvs/veyepar/bin/activate
(veyepar) [gstreamer-full] videoteam@mo:~/gstreamer/builddir$ python3 ~/gslevels.py --test 
...
  File "/home/videoteam/gslevels.py", line 42, in mk_pipe
    self.pipeline = Gst.parse_launch( pipeline )
                    ~~~~~~~~~~~~~~~~ ^^^^^^^^^^^^
gi.repository.GLib.GError: gst_parse_error: no element "decklink2srcbin" (1)

```

> <https://github.com/CarlFK/veyepar/blob/master/dj/lib/gslevels.py>

(sorry i looking at my code hurts. “For better or for worse, Python makes it easy and fun to write bad code.”)

I doubt the python virtualenv is relevant - I activated it both before/after, no help.