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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 Feb 13 '14 at 10:08

This question came from our site for system and network administrators.

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 '14 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? – kstratis Feb 12 '14 at 16:48
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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