Kaltura - Known Issue - Some machine captions have timings that are off or not aligned (Resolved)

This document describes a known issue where machine captions ordered from Kaltura may sometimes be created with timings that are off. This causes some (or all) captions after a certain point in the video to display at the wrong time.


This affects users who order machine captions through Kaltura as described in document Kaltura - Ordering machine captions for media in Kaltura MediaSpace. As of 9/21/20 Learn@UW-Madison has received reports of 3 instances of this behavior out of ~8.2k machine caption orders.


After investigating Kaltura believes the issue was the result of unexpected behavior due to their cloud migration work and should not occur again. If you find you have captions that are not in sync with the video you can try the workarounds below. Please also report the issue to the DoIT Help Desk for investigation and escalation to the Learn@UW-Madison team.


Option 1: Use the alignment tool to realign the machine captions

Since all machine captions automatically generate a text file, we can realign the captions by following the steps below:

  1. Go to mediaspace.wisc.edu, login and scroll or search for the video whose captions you want to re-align.
  2. Click Actions → Caption & Enrich.
  3. Click the Feature drop-down menu and select Alignment.
  4. The text file of the existing .SRT file will automatically appear as an option. If it is not already selected click the radio button next to it.  
  5. Click Submit. The captions will be re-processed and returned with more accurate timings.

More information on using the Kaltura alignment tool is available in Kaltura - Using a script to create captions for media in Kaltura MediaSpace.

Option 2: Re-upload video and re-order machine captions

This takes more time but because you can't re-order machine captions on a video, an alternative is to re-upload your video to Kaltura MediaSpace and order machine captions on it again. Since the issue is extremely intermittent the re-ordered machine captions on the new entry should have the correct timings.

Keywords:kaltura, mediaspace, video, caption, subtitle, timing, time, off, error, issue, bug, alignment   Doc ID:106015
Owner:Learn@UW Madison .Group:Learn@UW-Madison
Created:2020-09-21 09:51 CDTUpdated:2020-10-01 10:46 CDT
Feedback:  0   0