# Problems with Opening PsychAudioPort multiple times in parallel on Ubuntu

**URL:** <https://psychtoolbox.discourse.group/t/problems-with-opening-psychaudioport-multiple-times-in-parallel-on-ubuntu/3808>\
**Category:** Programming Help\
**Tags:** linux, audio\
**Created:** [April 11, 2021, 1:37am UTC](https://psychtoolbox.discourse.group/t/problems-with-opening-psychaudioport-multiple-times-in-parallel-on-ubuntu/3808 "2021-04-11T01:37:08Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![DBermudez0](https://avatars.discourse-cdn.com/v4/letter/d/3ab097/32.png) [@DBermudez0](https://psychtoolbox.discourse.group/u/DBermudez0)\
**Post date:** [April 11, 2021, 1:37am UTC](https://psychtoolbox.discourse.group/t/problems-with-opening-psychaudioport-multiple-times-in-parallel-on-ubuntu/3808/1 "2021-04-11T01:37:08Z")

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nrchannels = 2  
pahandle1 = PsychPortAudio(‘Open’, [], 1, [], [], nrchannels, [], 0.015);  
pahandle2 = PsychPortAudio(‘Open’, [], 1, [], [], nrchannels, [], 0.015);  
pahandle3 = PsychPortAudio(‘Open’, [], 1, [], [], nrchannels, [], 0.015);

Get the following error:

PTB-ERROR: Failed to open audio device 3. PortAudio reports this error: Device unavailable  
PTB-ERROR: Could not open audio device, most likely because it is already in use by a previous call to  
PTB-ERROR: PsychPortAudio(‘Open’, …). You can open each audio device only once per session. If you need  
PTB-ERROR: multiple independent devices simulated on one physical audio device, look into use of audio  
PTB-ERROR: slave devices. See help for this by typing ‘PsychPortAudio OpenSlave?’.  
Error in function Open: Usage error  
Audio device unavailable. Most likely tried to open device multiple times.  
Error using PsychPortAudio  
Usage:

pahandle = PsychPortAudio(‘Open’ [, deviceid][, mode][, reqlatencyclass][, freq][, channels][, buffersize][,  
suggestedLatency][, selectchannels][, specialFlags=0]);

Error in PAPI\_Pro\_main (line 321)  
pahandle1 = PsychPortAudio(‘Open’, [], 1, [], [], nrchannels, [], 0.015);

How do I fix it? Already installed all the dependencies to run Psychtoolbox on Linux. Sometimes the PsychPortAudio opens the devise but other time I get this error.

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**Author:** ![dcnieho](https://avatars.discourse-cdn.com/v4/letter/d/779978/32.png) [@dcnieho](https://psychtoolbox.discourse.group/u/dcnieho)\
**Post date:** [April 11, 2021, 5:36am UTC](https://psychtoolbox.discourse.group/t/problems-with-opening-psychaudioport-multiple-times-in-parallel-on-ubuntu/3808/2 "2021-04-11T05:36:30Z")

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do you close it after you open it (so before you run your script again)? It may be in use from a previous session?

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<div class="post-metadata">

**Author:** ![DBermudez0](https://avatars.discourse-cdn.com/v4/letter/d/3ab097/32.png) [@DBermudez0](https://psychtoolbox.discourse.group/u/DBermudez0)\
**Post date:** [April 11, 2021, 3:07pm UTC](https://psychtoolbox.discourse.group/t/problems-with-opening-psychaudioport-multiple-times-in-parallel-on-ubuntu/3808/3 "2021-04-11T15:07:50Z")

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Hi,

Now I close it after I open each one of the portaudio, but now I get an error later in the script:  
Error in function FillBuffer: Usage error  
Invalid audio device handle provided.

for the line:  
PsychPortAudio(‘FillBuffer’, pahandle1, S1);  
what does that error mean and how do I fix it?

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<div class="post-metadata">

**Author:** ![dcnieho](https://avatars.discourse-cdn.com/v4/letter/d/779978/32.png) [@dcnieho](https://psychtoolbox.discourse.group/u/dcnieho)\
**Post date:** [April 11, 2021, 4:20pm UTC](https://psychtoolbox.discourse.group/t/problems-with-opening-psychaudioport-multiple-times-in-parallel-on-ubuntu/3808/4 "2021-04-11T16:20:12Z")

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Close them at the end of your script, they need to be open until you no longer need them

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**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\
**Post date:** [April 12, 2021, 5:33pm UTC](https://psychtoolbox.discourse.group/t/problems-with-opening-psychaudioport-multiple-times-in-parallel-on-ubuntu/3808/5 "2021-04-12T17:33:10Z")

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Unless you want to use three separate physical sound cards simultaneously, that is the wrong approach. Use of audio slave devices (`PsychPortAudio OpenSlave?`), as described in PTB’s output, is the way to go if you want to use one physical sound card. We have multiple demos for this, e.g. BasicAMAndMixScheduleDemo.m. If you need further help with the approach from myself, please get your lab to buy priority support.

-mario