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Kaltura - Known Issue - Audio Issues with Some MacOS Powerpoint MP4 files [UW-Madison]

This document describes an issue where some macOS exported MP4 or MOV files when processed by Kaltura MediaSpace will have silence at the start or audio glitches even though there is supposed to be audio.


Some macOS Powerpoint 365 users have experienced this issue. We have not been able to identify the common thread between the users that causes the issue as it does not happen to all users.  Once a user's Powerpoint for macOS installation starts producing problematic MP4 files, it will do so consistently. These files do not prove problematic for only Kaltura MediaSpace - they will also have issues in many other applications as well.


This issue is present. Technologists are working with Kaltura and Microsoft on the issue.


  • Load the macOS Powerpoint 365 file in Windows Powerpoint 365 and re-export the MP4 video file. This file will be processed correctly by Kaltura MediaSpace.
  • With the media open in Kaltura MediaSpace click Actions > Launch Editor. Click Save a Copy. Name the copy of your media and click Create. A new entry will be created that should have the audio processed correctly.
    Technologists have identified one case where it did not. In this case two users collaborated on a file and recorded audio using different microphones. This may also happen when embedding audio or video of a different bitrate or sample rate than narrated audio. In this case the only workaround was to load it in Windows Powerpoint, export it as an MP4 there.
  • We normally recommend users upload media to Kaltura MediaSpace due to the extra functionality offered, but users can upload an affected MP4 to Canvas using the Record/Upload media function if your file is under 500MB.
Alternately affected users may want to choose a different tool to create instructional videos until Microsoft and/or Kaltura can remedy the issue.

Keywordskaltura, media, video, mov, mp4, upload, glitch, issue, bug,   Doc ID101841
OwnerLearn@UW MadisonGroupLearn@UW-Madison
Created2020-05-08 09:31:58Updated2023-12-20 14:37:28
SitesDoIT Help Desk, Learn@UW-Madison
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