# GStreamer startup failure on Windows - Persistent Error Code 126

**URL:** <https://psychtoolbox.discourse.group/t/gstreamer-startup-failure-on-windows-persistent-error-code-126/3285>\
**Category:** Programming Help\
**Tags:** windows\
**Created:** [July 7, 2020, 3:21pm UTC](https://psychtoolbox.discourse.group/t/gstreamer-startup-failure-on-windows-persistent-error-code-126/3285 "2020-07-07T15:21:28Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![MatlabLPlates](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@MatlabLPlates](https://psychtoolbox.discourse.group/u/MatlabLPlates)\
**Post date:** [July 7, 2020, 3:21pm UTC](https://psychtoolbox.discourse.group/t/gstreamer-startup-failure-on-windows-persistent-error-code-126/3285/1 "2020-07-07T15:21:28Z")

</div>

Hello-  
I am having difficulty running a script called HandCoding1\_v3. the script involves loading in a simple video, but no matter what I try, I get this error:

PTB-ERROR: Tried to startup GStreamer multi-media framework. This didn’t work, because one  
PTB-ERROR: of the required GStreamer runtime libraries failed to load, probably because it  
PTB-ERROR: could not be found, could not be accessed (e.g., due to permission problems),  
PTB-ERROR: or most likely because GStreamer isn’t installed on this machine at all.  
PTB-ERROR: Another reason could be that you have GStreamer version 0.10.x instead of the required  
PTB-ERROR: version \>= 1.4.0 installed. The version 0.10 series is no longer supported.

**PTB-ERROR: The system returned the error code 126.**  
PTB-ERROR: Please read the help by typing ‘help GStreamer’ for installation and troubleshooting  
PTB-ERROR: instructions.

PTB-ERROR: Due to failed GStreamer initialization, the movie playback engine is disabled for this session.

Error in function OpenMovie: Usage error  
GStreamer initialization failed due to library loading problems. Aborted.

WARNING: This session of your experiment was run by you with the setting Screen(‘Preference’, ‘SkipSyncTests’, 2).  
WARNING: This means that some internal self-tests and calibrations were skipped. Your stimulus presentation timing  
WARNING: may have been wrong. This is fine for development and debugging of your experiment, but for running the real  
WARNING: study, please make sure to set Screen(‘Preference’, ‘SkipSyncTests’, 0) for maximum accuracy and reliability.  
Error using Screen  
Usage:

[moviePtr [duration] [fps] [width] [height] [count] [aspectRatio]]=Screen(‘OpenMovie’, windowPtr, moviefile [, async=0] [, preloadSecs=1] [, specialFlags1=0][,  
pixelFormat=4][, maxNumberThreads=-1][, movieOptions]);

Error in HandCoding1\_v3 (line 114)  
[mov1 dur1 fps1 h1 w1 framecount1] = Screen(‘OpenMovie’, EXPWIN, MovieName1);

I initially believed the issue to be related to a versioning error with G-streamer; however, I have upgraded to Matlab 2020 and the latest version of psychtoolbox and G-Streamer and seen no change. I am working on a HP laptop with Windows 10.

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<div class="post-metadata">

**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\
**Post date:** [July 9, 2020, 8:18pm UTC](https://psychtoolbox.discourse.group/t/gstreamer-startup-failure-on-windows-persistent-error-code-126/3285/2 "2020-07-09T20:18:19Z")

</div>

Please post all the Matlab command window output, from the moment you launch Matlab. The startup messages should be diagnostic, and also give you additional troubleshooting instructions if something is detected as wrong. And make sure your PTB is up to date at the latest 3.0.16 beta release, and you really installed the packages mentioned in “help GStreamer”.

---

<div class="post-metadata">

**Author:** ![MatlabLPlates](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@MatlabLPlates](https://psychtoolbox.discourse.group/u/MatlabLPlates)\
**Post date:** [July 24, 2020, 5:37pm UTC](https://psychtoolbox.discourse.group/t/gstreamer-startup-failure-on-windows-persistent-error-code-126/3285/3 "2020-07-24T17:37:35Z")

</div>

I have checked that I am on the most recent installations of both psychtoolbox and gstreamer. Here is the output as requested:

HandCoding1\_v3

ans =

```
 1

```

PTB-INFO: This is Psychtoolbox-3 for Microsoft Windows, under Matlab 64-Bit (Version 3.0.15 - Build date: Feb 7 2019).  
PTB-INFO: Support status on this operating system release: Windows 10 (Version 10.0) supported and tested to some limited degree.  
PTB-INFO: Type ‘PsychtoolboxVersion’ for more detailed version information.  
PTB-INFO: Most parts of the Psychtoolbox distribution are licensed to you under terms of the MIT License, with  
PTB-INFO: some restrictions. See file ‘License.txt’ in the Psychtoolbox root folder for the exact licensing conditions.

PTB-INFO: Most graphics cards will not support proper syncing to vertical retrace when  
PTB-INFO: running in windowed mode (non-fullscreen). If PTB aborts with ‘Synchronization failure’  
PTB-INFO: you can disable the sync test via call to Screen(‘Preference’, ‘SkipSyncTests’, 2); .  
PTB-INFO: You won’t get proper stimulus onset timestamps though, so windowed mode may be of limited use.

PTB-INFO: OpenGL-Renderer is Intel :: Intel® UHD Graphics 620 :: 4.6.0 - Build 26.20.100.7926  
PTB-INFO: VBL startline = 1080 , VBL Endline = -1  
PTB-INFO: Beamposition queries unsupported or defective on this system. Using basic timestamping as fallback.  
PTB-INFO: Timestamps returned by Screen(‘Flip’) will be therefore less robust and accurate.  
PTB-INFO: Measured monitor refresh interval from VBLsync = 0.000000 ms [inf Hz]. (0 valid samples taken, stddev=0.000000 ms.)  
PTB-INFO: Reported monitor refresh interval from operating system = 16.666667 ms [60.000000 Hz].  
PTB-INFO: Small deviations between reported values are normal and no reason to worry.  
PTB-WARNING: ==============================================================================================================================  
PTB-WARNING: WINDOWS DWM DESKTOP COMPOSITOR IS ACTIVE! ALL FLIP STIMULUS ONSET TIMESTAMPS WILL BE VERY LIKELY UNRELIABLE AND LESS ACCURATE!  
PTB-WARNING: STIMULUS ONSET TIMING WILL BE UNRELIABLE AS WELL, AND GRAPHICS PERFORMANCE MAY BE SEVERELY REDUCED! STIMULUS IMAGES MAY NOT  
PTB-WARNING: SHOW UP AT ALL! DO NOT USE THIS MODE FOR RUNNING REAL EXPERIMENT SESSIONS WITH ANY REQUIREMENTS FOR ACCURATE TIMING!  
PTB-WARNING: ==============================================================================================================================  
PTB-INFO: All display tests and calibrations disabled. Assuming a refresh interval of 60.000000 Hz. Timing will be inaccurate!

MovieName1 =

```
'C:\Users\Local User\Desktop\coding vids\10_1_sol1c_inf_left.MP4'

```

PTB-ERROR: Tried to startup GStreamer multi-media framework. This didn’t work, because one  
PTB-ERROR: of the required GStreamer runtime libraries failed to load, probably because it  
PTB-ERROR: could not be found, could not be accessed (e.g., due to permission problems),  
PTB-ERROR: or most likely because GStreamer isn’t installed on this machine at all.  
PTB-ERROR: Another reason could be that you have GStreamer version 0.10.x instead of the required  
PTB-ERROR: version \>= 1.4.0 installed. The version 0.10 series is no longer supported.

PTB-ERROR: The system returned the error code 126.  
PTB-ERROR: Please read the help by typing ‘help GStreamer’ for installation and troubleshooting  
PTB-ERROR: instructions.

PTB-ERROR: Due to failed GStreamer initialization, the movie playback engine is disabled for this session.

Error in function OpenMovie: Usage error  
GStreamer initialization failed due to library loading problems. Aborted.

WARNING: This session of your experiment was run by you with the setting Screen(‘Preference’, ‘SkipSyncTests’, 2).  
WARNING: This means that some internal self-tests and calibrations were skipped. Your stimulus presentation timing  
WARNING: may have been wrong. This is fine for development and debugging of your experiment, but for running the real  
WARNING: study, please make sure to set Screen(‘Preference’, ‘SkipSyncTests’, 0) for maximum accuracy and reliability.  
Error using Screen  
Usage:

[moviePtr [duration] [fps] [width] [height] [count] [aspectRatio]]=Screen(‘OpenMovie’, windowPtr, moviefile [, async=0] [, preloadSecs=1] [, specialFlags1=0][,  
pixelFormat=4][, maxNumberThreads=-1][, movieOptions]);

Error in HandCoding1\_v3 (line 114)  
[mov1 dur1 fps1 h1 w1 framecount1] = Screen(‘OpenMovie’, EXPWIN, MovieName1);

» HandCoding1\_v3

---

<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:** [July 24, 2020, 6:19pm UTC](https://psychtoolbox.discourse.group/t/gstreamer-startup-failure-on-windows-persistent-error-code-126/3285/4 "2020-07-24T18:19:25Z")

</div>

This does not contain all the output _since starting matlab_, only since running the script. Please post what is output directly when matlab is started.  
Furthermore, help GStreamer provides a link to the exact version that should be installed for maximum chance that things work. Please deinstall the latest GStreamer, and install the version linked to. Make sure you do a complete installation.

---

<div class="post-metadata">

**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\
**Post date:** [July 26, 2020, 12:02pm UTC](https://psychtoolbox.discourse.group/t/gstreamer-startup-failure-on-windows-persistent-error-code-126/3285/5 "2020-07-26T12:02:39Z")

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This is not the latest PTB version according to the output: “PTB-INFO: This is Psychtoolbox-3 for Microsoft Windows, under Matlab 64-Bit (Version 3.0.15 - Build date: Feb 7 2019).”.

Version 3.0.16 is, and 3.0.15 and 3.0.16 have different GStreamer requirements, 3.0.16 has greatly improved stability with Matlab on Windows.