mixed format missing mimetype

[jachym]

I think, that the mixed format should have mime_type forced to image/jpgpng

[jratike80]

Mapserver, Geoserver and GeoWebCache are using image/vnd.jpeg-png
https://mapserver.gis.umn.edu/ja/mapfile/outputformat.html
https://docs.geoserver.org/latest/en/user/services/wms/outputformats.html

[jachym]

Whatever will work

https://github.com/qgis/QGIS/blob/master/src/providers/wms/qgswmsprovider.cpp#L3693

[jratike80]

Then I would go for image/vnd.jpeg-png as a common OSGeo variant.

[jbo-ads]

+1 for image/vnd.jpeg-png