WARNING: erroneous pipeline: no element "gstplugin_py"

[balajiraghuram92]

Hi,
when Executing the project getting the following error:
the log for the program

$gst-inspect-1.0 --version
gst-inspect-1.0 version 1.15.0
GStreamer 1.15.0 (GIT)
Unknown package origin
$ export GST_PLUGIN_PATH=$PWD
$ gst-launch-1.0 videotestsrc ! videoconvert ! gstplugin_py ! videoconvert ! fakesink
0:00:00.016566538 29172 0xf59660 ERROR GST_PIPELINE grammar.y:816:priv_gst_parse_yyparse: no element "gstplugin_py"
0:00:00.016630488 29172 0xf59660 ERROR GST_PIPELINE grammar.y:901:priv_gst_parse_yyparse: link has no sink [source=@0xf5b3c0]
0:00:00.016665694 29172 0xf59660 ERROR GST_PIPELINE grammar.y:901:priv_gst_parse_yyparse: link has no source [sink=@0xf5c4e0]
WARNING: erroneous pipeline: no element "gstplugin_py"

Do we have to run the python program, if i run it getting following error:

$python gstplugin_py.py

(python:30326): GStreamer-WARNING **: External plugin loader failed. This most likely means that the plugin loader helper binary was not found or could not be run. You might need to set the GST_PLUGIN_SCANNER environment variable if your setup is unusual. This should normally not be required though.

I have built the gstreamer from lastest source.

Did you try the same thing or are you using a installer of gstreamer 1.14

If need any logs of the gstreamer or program,please give a reply.Will send you all the required information

[ghost]

the thing is, the python loader plugin is not properly installed or you are lacking to install the package called gobject-devel in your computer. To check if python plugin is installed run the command gst-inspect-1.0 python if python loader is installed it should show the details

in my case:

[flaskuser@localhost cli]$ gst-inspect-1.0 python
Plugin Details:
Name python
Description loader for plugins written in python
Filename /usr/lib64/gstreamer-1.0/libgstpython.cpython-36m-x86_64-linux-gnu.so
Version 1.14.3
License LGPL
Source module gst-python
Binary package GStreamer GObject Introspection overrides for Python
Origin URL http://gstreamer.freedesktop.org

0 features:

[flaskuser@localhost cli]$

[jackersson]

Hi @ejlungay,

Make sure you reproduced everything with installation and export:

export GST_PLUGIN_PATH=$GST_PLUGIN_PATH:$PWD/venv/lib/gstreamer-1.0/:$PWD/gst/

> GST_PLUGIN_PATH=$GST_PLUGIN_PATH:$PWD/venv/lib/gstreamer-1.0/:$PWD/gst/ gst-inspect-1.0 python
Plugin Details:
  Name                     python
  Description              loader for plugins written in python
  Filename                 /home/taras/coder/lifestyletransfer/gst-python-plugins-versions/gst-python-plugins/venv/lib/gstreamer-1.0/libgstpython.cpython-36m-x86_64-linux-gnu.so
  Version                  1.14.5
  License                  LGPL
  Source module            gst-python
  Binary package           GStreamer GObject Introspection overrides for Python 
  Origin URL               http://gstreamer.freedesktop.org

  gaussian_blur: GaussianBlur
  median_filter: Median Filter
  gstplugin_py: Name

  3 features:
  +-- 3 elements

Reproduced with docker container

Note: gstreamer-python package installs everything inplace

Hope this helps ;)
Best regards,

[codethief]

I'm experiencing the same issue. I installed gstreamer1.0-python3-plugin-loader on my Ubuntu 20.04 machine and, afterwards, gst-inspect-1.0 python showed:

$ gst-inspect-1.0 python
Plugin Details:
  Name                     python
  Description              loader for plugins written in python
  Filename                 /usr/lib/x86_64-linux-gnu/gstreamer-1.0/libgstpython.so
  Version                  1.16.2
  License                  LGPL
  Source module            gst-python
  Binary package           GStreamer Python
  Origin URL               http://gstreamer.freedesktop.org
  0 features:

Five minutes, later, however, after testing various Python plugins/transforms (among others, the ones in this repository), I suddenly got an Erroneous pipeline error and gst-inspect-1.0 python now says that it cannot find the Python plugin – even in the shell in which it had originally reported that the Python plugin was installed successfully, i.e. outside the venv I created for this repo! In those five minutes I didn't change anything about my system or my environment variables, though, and libgstpython.so is still where it was:

$ ls -l /usr/lib/x86_64-linux-gnu/gstreamer-1.0/libgstpython.so 
-rw-r--r-- 1 root root 23K Mär 24  2020 /usr/lib/x86_64-linux-gnu/gstreamer-1.0/libgstpython.so

I'm at a complete loss as to what happened and I've already apt purged and reinstalled gstreamer1.0-python3-plugin-loader to no avail. I would be very grateful for any pointers!

EDIT: Come to think of it, in those five minutes mentioned above, I followed the installation steps from https://github.com/jackersson/gst-python-plugins/blob/master/README.md . Did the installation of https://github.com/jackersson/gstreamer-python.git possibly change anything permanently about my setup (i.e. outside the venv)? Could it be that, e.g., there's a bug somewhere in https://github.com/jackersson/gstreamer-python/blob/master/build-gst-python.sh causing the script to write things to the wrong directory?

EDIT2: I just ran

sudo apt purge python3-gi python3-gst-1.0 gir1.2-gstreamer-1.0 gir1.2-gst-plugins-base-1.0 gir1.2-gst-plugins-bad-1.0 gir1.2-gst-rtsp-server-1.0 gstreamer1.0-python3-plugin-loader

(Careful! Due to gstreamer being a crucial dependency, this purges about a hundred other packages, too!)

followed by

sudo apt install python3-gi python3-gst-1.0 gir1.2-gstreamer-1.0 gir1.2-gst-plugins-base-1.0 gir1.2-gst-plugins-bad-1.0 gir1.2-gst-rtsp-server-1.0 gstreamer1.0-python3-plugin-loader
sudo apt install <all the other packages that were uninstalled previously>

and now gst-inspect-1.0 python reports that the Python plugin is available. (Thank god!) I have no idea what was going on but I'm somewhat afraid of installing gstreamer-python again.

EDIT3: I couldn't resist and tried setting up gst-python-plugins again. First, I tried installing gstreamer-python without gst-python (which failed). Then I bit the bullet and followed the ordinary setup instructions of gst-python-plugins again. Once again, gst-inspect-1.0 python now reports No element or plugin »python«. Therefore, I am now certain that gstreamer-python modifies dependencies on a system level, even when it is installed inside a virtual environment. (I have no idea, how it does that, though, as I didn't execute any command as root.)

Unfortunately, my previous "fix" of reinstalling all packages no longer does the trick. Once again, libgstpython.so is still in place and it seems gst-inspect can find it, too:

$ GST_DEBUG="*:5" gst-inspect-1.0 python
[…]
0:00:00.214735190 30432 0x55578ba6f400 DEBUG           GST_REGISTRY gstregistry.c:461:gst_registry_add_plugin:<registry0> adding plugin 0x55578bbe3d30 for filename "/usr/lib/x86_64-linux-gnu/gstreamer-1.0/libgstpython.so"
0:00:00.214742851 30432 0x55578ba6f400 DEBUG           GST_REGISTRY gstregistrychunks.c:878:_priv_gst_registry_chunks_load_plugin: Added plugin 'libgstpython.so' plugin with 0 features from binary registry
[…]
No such element or plugin 'python'

I'm at a complete loss now. :|

[ghost]

Solved the problem
install python3-gstreamer1 python3-devel

[codethief]

@ejlungay What kind of packages are these? I can't find them in the Ubuntu repositories.

[alhoo]

There seems to be something wrong with the instructions. Edit: This comment contained a bad Dockerfile. Working dockerfile available in the end of this thread.

[ghost]

Solved the problem
install python3-gstreamer1 python3-devel

@ejlungay What kind of packages are these? I can't find them in the Ubuntu repositories.

@codethief

search packages via apt and find gstreamer

get the result of the search and install

[alhoo]

 $ apt-cache search python3-gstreamer1

does not return anything. Maybe you are referring to one of these:

 $ apt-cache search gstreamer|grep python
gstreamer1.0-python3-dbg-plugin-loader - GStreamer Loader for Python Plugin (Python 3, debug extensions)
gstreamer1.0-python3-plugin-loader - GStreamer Loader for Python Plugin (Python 3)
python-audioread - Backend-agnostic audio decoding Python package
python-gst-1.0 - GStreamer GObject Introspection overrides for Python
python-gst-1.0-dbg - GStreamer GObject Introspection overrides for Python (debug extensions)
python3-gst-1.0 - GStreamer GObject Introspection overrides for Python (Python 3)
python3-gst-1.0-dbg - GStreamer GObject Introspection overrides for Python (Python 3, debug extensions)

[alhoo]

Ok finally got it working with:

FROM ubuntu:18.04

USER root

RUN apt-get update && apt-get -y --no-install-recommends install \
    build-essential \
    git \
    cmake \
    autoconf \
    automake \
    libtool \
    pkg-config \
    python3.6 \
    python3-pip \
    python3-dev


RUN apt-get -y --no-install-recommends install \
    gstreamer-1.0 \
    gstreamer1.0-dev \
    gstreamer1.0-plugins-base \
    gstreamer1.0-tools \
    libgstreamer1.0-0 \
    libgstreamer1.0-0 \
    libgirepository1.0-dev \
    libgstreamer-plugins-base1.0-dev \
    libcairo2-dev \
    gir1.2-gstreamer-1.0 \
    python-gst-1.0 \
    python3-gi \
    gstreamer1.0-python3-plugin-loader
    # python-gi-dev

RUN pip3 install -U wheel pip setuptools

RUN pip3 install git+https://github.com/jackersson/gstreamer-python.git#egg=gstreamer-python

RUN ln -s /usr/lib/x86_64-linux-gnu/gstreamer-1.0/libgstpython.cpython-36m-x86_64-linux-gnu.so /usr/lib/x86_64-linux-gnu/gstreamer-1.0/libgstpython.so

ARG DEBIAN_FRONTEND=noninteractive
RUN apt-get -y --no-install-recommends install python3-opencv

ADD gst gst
ENV GST_PLUGIN_PATH /usr/lib/gstreamer-1.0/:/gst/
CMD gst-inspect-1.0 gaussian_blur

Results:

$ docker build -t gstreamer-python . && docker run -it gstreamer-python
Factory Details:
  Rank                     none (0)
  Long-name                GaussianBlur
  Klass                    Filter
  Description              Apply Gaussian Blur to Buffer
  Author                   Taras Lishchenko <taras at lifestyletransfer dot com>

Plugin Details:
  Name                     python
  Description              loader for plugins written in python
  Filename                 /usr/lib/x86_64-linux-gnu/gstreamer-1.0/libgstpython.so
  Version                  1.14.5
  License                  LGPL
  Source module            gst-python
  Binary package           GStreamer GObject Introspection overrides for Python 
  Origin URL               http://gstreamer.freedesktop.org
...

Thanks @ejlungay!

[aanishatdatakalp]

i have been getting the same error on my jetson nano
WARNING: erroneous pipeline: no element "gstplugin_py"
i tried to reproduce it with a Ubuntu18 docker container setuphttps://github.com/jackersson/env-setup and it works fine.
i have followed the installation process and the export and there were no errors.
Due to some reasons i don't want to use the docker container.

[ghost]

i have been getting the same error on my jetson nano WARNING: erroneous pipeline: no element "gstplugin_py" i tried to reproduce it with a Ubuntu18 docker container setuphttps://github.com/jackersson/env-setup and it works fine. i have followed the installation process and the export and there were no errors. Due to some reasons i don't want to use the docker container.

@aanishatdatakalp
When writing gst-plugins in python, you should format your structure like this:
python
app.py

where:
python is a folder in root directory

when running your program, you must do:
export GST_PLUGIN_PATH=$PWD

then you can verify if your python plugin is working by:
gst-inspect-1.0 <name_of_plugin_you_made>