Sorry, I misunderstood your post but currently, except for QMediaRecorder, I don't know if there's a way to have the list of decoders.

Hi, 32bit Windows 7 Home Edition.

Anyway maybe I found a workaround. In case an error occurs when trying to play the movie, there is a maximum number of retries...
I have done this because my suspect is that, due to the CF-19 "poor" performances, the libraries aren't (fully) loaded when the movie is played.

I will keep you up to date whether this is or this is not THE solution, for anyone else's benefit.

Thanks to everybody!