Editor claims "No Thumbnail available" even if there is a thumbnail

[oas777]

A question rather than a bug report at this stage: Is it correct that the editor always displays "No Thumbnail available" - even if the video definitively has a preview image (displayed in the "Cutting" part of the editor)? Given this is different when I manually define a new thumbnail with the editor (upload or generated from video) - does the editor not identify the auto-generated thumbnails as such?

[oas777]

PS: Not sure this is related, but track selection does not show a preview either, cf.

https://tobira.opencast.org/events/opencast/2022/osnabruck-dach/v/OeIxIsbHRz8 or

https://tobira-test-oc.ethz.ch/editor-ui/index.html?id=4ff450f0-1210-4c22-b5bf-22b4739052b7&callbackUrl=https%3A%2F%2Ftobira.opencast.org%2F%7Emanage%2Fvideos%2FOeIxIsbHRz8&callbackSystem=Tobira+Test+Deployment

[mtneug]

My understanding is that this all depends on your workflows in Opencast, so basically you can configure whatever you want here.

If the workflows create an automated thumbnail and add it to the mediapackage in the same way as the editor does for manual uploads, it should be displayed here. Personally, I don't do that to distinguish between automated and manual thumbnails. The "No Thumbnail available" is thus more a "No manual thumbnail available".

Other (video) thumbnails used in various views of the editor also don't need to correspond to the ones depicted in the player. The workflow preparing assets for editing can decide what is being generated here. For instance, I use the frame at a specific location as the representation of that track. This is very different from the automated player thumbnail generated using the video's metadata.

[oas777]

Thanks @mtneug for a very accurate description of the mess Opencast is with respect to thumbnails. However, improving the user experience (not yours and mine but the end user's) requires a different welcome than "No manual thumbnail available" when a thumbnail can be seen by the user - regardless where it comes from. https://tobira.opencast.org/, https://editor.opencast.org/19.x/, and the video editor here at ETH have that problem. Are you saying that "that this all depends on your workflows" or is there something to be improved in Opencast and/or Tobira per se? @Arnei?

[Arnei]

I agree that the editor should show thumbnails regardless where they come from. While there are potentially different types of thumbnails, the thumbnail editor is effectively for player thumbnails currently, and as such should show automated thumbnails.

Since this "depends on your workflows", the Opencast workflows are what could be improved upon here. I recently tried this in a "wrong" manner (opencast/opencast#7836), so somebody (maybe me) should do this in a right manner in my opinion.