Could not find appropriate writer for thumbnail "…", attempting conversion.

[Lanceeeelot]

My extraction config currently has the default setup (except paths) after switching to a new more powerful linux PC. Now Cineast CLI always displays that "ShotThumbnailsExporter" warning mentioned in the title. Other than that, the extraction works normally.

[sauterl]

Do you get a follow-up error with Could not find appropriate writer for thumbnail "...", even after conversion! ?

If not, then you are somewhat fine, as apparently (based on your context) the default format for thumbnails does not work anymore on this specific JDK / OS / hardware configuration. The default should be JPG, but may you changed something somewhere. For further information on the issue, see ImageIO.write for OpenJDK 21.

If so, then you are somewhat restricted, as no thumbnails have been created.

See https://github.com/vitrivr/cineast/blob/main/cineast-core/src/main/java/org/vitrivr/cineast/core/features/exporter/ShotThumbnailsExporter.java#L85

In such cases, it would be very helpful to have the following information:

• JDK version
• OS version
• Cineast commit hash / version
• Cineast config / Job config
• Minimal example with media file, if possible

[Lanceeeelot]

Thankfully i don’t get a follow-up error. All the thumbnails were generated and Vitrivr-NG is able to find them. I’m using OpenJDK Version 21.0.3, Ubuntu 24.04 LTS and the latest Cineast version from the main branch.

I noticed a comment in your linked script that says that the thumbnail output format defaults to PNG. All my generated Thumbnails are JPG though, like you said.

See https://github.com/vitrivr/cineast/blob/main/cineast-core/src/main/java/org/vitrivr/cineast/core/features/exporter/ShotThumbnailsExporter.java#L32

I also didn’t change anything in the extraction_config regarding the exporter settings:

"exporters":[
   	 {
   		 "name": "ShotThumbnailsExporter",
   		 "properties": {
   			 "destination":"thumbnails/"
   		 }
   	 }
    ],