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Problems with sound recorder (Mac OS X)

edited May 2016 in OpenSesame

Hi everybody,

First of all: I'm new to both OpenSesame, Python and coding in general. So I'm sorry if my problem/question seems trivial.

I created an experiment requiring participants to repeat visual and/or audio stimuli aloud. The general set-up of the experiment works perfectly, but I'm running into problems when it comes to recording the audio response. I installed the sound_start_recording and sound_stop_recording plugins (0.13 on Mac OS X 10.11) and set the compression preferences in the experiment to "None (wav)". As soon as I start the experiment with the sound recorder plugins inserted, it crashes when calling the first stimulus (without the plugins everything runs smoothly throughout the entire experiment) and I get the following error messages:


item-stack: experiment[run].practice_loop[run].practice_sequence[prepare].new_sound_start_recording[prepare]
exception message: No module named muxer
time: Mon May 16 17:56:15 2016
exception type: ImportError

and Traceback:

File "/Applications/", line 38, in execute
  File "/Applications/", line 397, in run
  File "/Applications/", line 95, in execute
  File "/Applications/", line 110, in run
  File "/Applications/", line 50, in run
  File "/Applications/", line 110, in run
  File "/Applications/", line 144, in run
  File "/Applications/", line 94, in execute
  File "/Applications/", line 126, in prepare
  File "/Applications/", line 121, in prepare
  File "/Applications/", line 126, in prepare
  File "/Applications/", line 96, in prepare
  File "/Applications/", line 35, in <module>
ImportError: No module named muxer

Google tells me that muxer belongs to PyMedia but I wanted to use the wave module which should be installed I guess?!
Hope this makes any sense at all. I'd be really grateful for any advice!

In case it helps solving the problem: I use Python 2.7 and this is what my environment looks like:




  • edited May 2016

    Hi Sophia,

    You're right, muxer belongs to pymedia, which is a library which hasn't been updated for ages. Sadly, back when I wrote this plugin, it was the only easy way to record sound and even if you use wav recording, it still uses pymedia. Pymedia is known to break on newer python installations, and has never been thoroughly tested on a Mac. The only thing I can advise you is to try to run your experiment on Windows. There is less chance of breakage there because the correct version of pymedia is packaged with OpenSesame itself.

    I'm working on updates regarding the multimedia capabilities for OpenSesame, but I'm not quite there yet. Hopefully I will have some new plugins to replace the old pymedia ones soon. Sorry to be of no more help at the moment.

  • edited 9:30AM

    Hi Daniel,

    Thank you very much for your reply! It saved me a lot of time trying to get the plugin to work with another library.

    I'm glad to hear that new multimedia plugins might be coming soon. That sounds very promising for future projects.

    Good luck on and thanks again!

  • Has there been any update on this? I'm getting the same error. OS 10.12, OpenSesame 3.1.7, Python 2.7.

  • I suspect that this is simply an issue of pymedia not being installed. However, it doesn't seem straightforward to install pymedia on Mac OS. You can first try to figure out how to install pymedia. But if that doesn't work, then I second @Daniel's suggestion to use a Windows system instead.

  • Is there an update on sound recorder plugin ? I am experiencing the same issue with an ubuntu laptop.

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