Videos fail to play - only audio plays

Nextcloud version 23.0.0
Operating system and version Synology DSM 7.x
Apache or nginx version 2.4.52 (Debian)
PHP version 8.0.14

The issue you are facing:

Uploading videos from my Samsung S21 to Nextcloud produces videos that do not play in Nextcloud. That is the video does not display. The audio works but the video doesn’t. If I download the video and play it locally it works. I suspect the built-in video player has some sort of problem.

Here’s a sample -

Is this the first time you’ve seen this error? N

Steps to replicate it:

  1. Take a video using something like a Samsung S21
  2. Upload it to Nextcloud
  3. Play the video back

Your video is HEVC/H.265. Edge is the only web browser that can play H.265 and even then only with the HEVC plugin installed from the microsoft store.

Set your video to H264/Compatibility mode to fix this in your phone. (assuming samsung allows this)

I knew it was something dumb like that. Galaxy S21/Ultra/Plus: How to Enable/Disable High Efficiency talks about how to turn this on or of but what it fails to mention is that High efficiency videos (labeled as Reduce file size on my S21) is greyed out unless you also toggle off HDR10+ videos (Labs). Now videos play just fine. Thanks.