[open] GST media player too slow on a computer

mpiter

Hello,

I successfully ran an audiovisual experiment on a couple of Linux or Windows computers using GST media player to run the videos. On an old Windows student computer, the standalone VLC program can run the videos but Opensesame cannot with GST media player. The video starts but the image stays frozen while the sound is playing and the rest of the experiment successfully runs. It looks like the computer lacks computing resources for the job. Is there any settings that might be tried to run the videos within Opensesame? We plan to install Linux on the small laptop and to try with Linux Mint 17.2. Thanks in advance for any piece of information.

pit

Daniel

Hi pit,

I have also noticed the gst player runs badly on slower computers, but I haven't been able to find a solution to this. It has to do with how GST delivers the frames to OpenSesame, which in turn has to render these as textures on the screen. The conversion to a texture is quite slow and resource intensive. GST 1.x (OpenSesame uses 0.10.x) promises to solve this but I haven't come around to porting the module to the newer GST version.

For now, there are three solutions:
1. Recompress the video to a lower resolution/bitrate and/or framerate. The less (and smaller) frames that need to be rendered, the lower the resource costs, and the higher the chances that it does work as intended.
2. Use a more powerful pc. This sounds lame, but it is a good idea to always run experiments on computers that are up to the job, otherwise timing measurements might also be impeded or less reliable.
3. Use the vlc media player version. You mentioned that it works. Why not use that one?

Good luck, and let us know if any of these options work out for you.

mpiter

Hi Daniel,

Thanks for your quick reply.

I will try the VLC plugin this week-end. I have not tried it yet because I thought that I would find the same loss as with the GST plugin and I have never tried the VLC one in Opensesame. Now that I know that it might work better, I will learn how to use it and I will try it this week-end.

Unfortunately I have a talk to present tomorrow morning, and as usual I am a bit late. So I will not be able to try the plugin today despite my impatience. But I will report the result as soon as it is done.

Thanks again for your support.

mpiter

Hi,

I could not make the VLC plugin to work in Linux. Opensesame cannot find the vlc module at importation time. When I drag the VLC plugin icon inside my experiment, I receive an error message ending by this:

      File "/usr/share/opensesame/plugins/media_player_vlc/media_player_vlc.py", line 32, in <module>
        import vlc
    ImportError: No module named vlc

I have updated Linux Mint 17.1 to the last 17.2 and Opensesame 2.9.x to 3.0 for the same result. VLC was installed a long time ago by the usual apt-get install vlc. I have not found a solution in the Internet. I saw Dan on your VLC plugin Web page that VLC must be installed in its default location. I assume that apt-get install does it properly. What must be done to be able to import the vlc module in python 2.7.5?

Thanks for any piece of information.

sebastiaan

Hi,

Right, you need the Python bindings for the VLC player (vlc.py). You can grab those from here:

• https://wiki.videolan.org/Python_bindings

If you place vlc.py somewhere in the Python path, which includes the plugin folder, it should work.

Cheers!
Sebastiaan

mpiter

Thanks to both of you. We did not manage to run the VLC plugin without glitches in Windows but it runs perfectly well with Linux. The student can take his old computer at home to carry out the experiment with friends. That makes his life easier :-)