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On a Windows Server 2012 R2 machine, I'm running a small python script as a windows service according to this post: Start python .py as a service in windows.

What my script does is to essentially call Microsoft Powerpoint 2013 and ask it to export a given .ppt presentation as a video file. (This was made possible using the pywin32 extensions).

The problem is that when I start the script as a service and then 'feed' it with the presentation file, the resulting video file contains no audio track even though the original .ppt file contains plenty of sound effects and a background music track thoughout).

However, if I run the python script separately in a new command line prompt and then 'feed' it with the same presentation file, the resulting video file comes out just fine with full audio.

I've made sure that the services:

  • Windows Audio
  • Windows Audio Endpoint Builder

are both running and that Microsoft Office products can create files and folders following these posts:

  1. Link 1
  2. Link 2

Any ideas why Powerpoint can't export any audio when called from a local system service?

Thanks in advance.

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migrated from serverfault.com Feb 13 at 10:08

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1  
Do you dump any logs out from your script, they could be helpful in figuring out why it's not working. My gut feeling is permissions. –  Steve Butler Feb 12 at 16:12
    
Unfortunately Powerpoint doesn't give any error logs in this case. I can only get indication of whether the conversion completed successfully or not by checking the presentation.CreateVideoStatus for 0 or 1. However the conversion seems to always succeed but is does so without any sound. Assuming the problem lies within the permissions, how would you suggest to fix it? –  Konos5 Feb 12 at 16:48

1 Answer 1

up vote 0 down vote accepted

To answer my own question for future reference;

It seems that installing a virtual sound card driver solves the problem. Somehow on startup Powerpoint seems to look for audio cards and if it finds none it omits the audio track during the conversion-to-video.

By installing the fake driver, Powerpoint is eventually tricked into a false positive and performs the conversion without a hitch.

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