Issue with saving video frame in natural size

I am working with/annotation video data I have recorded myself (.mp4), and I would like to save some video stills. Using “Save Current Frame in Natural Size…” yields an empty warning message. Any idea what could be the matter? It works just fine with video data from the Corpus NGT.

Thanks for reporting this, I’m afraid I can reproduce that error with some mp4 videos (others work fine).
A message in the log reveals that the buffer that ELAN creates for the image pixels (based on width, height, number of bytes per pixels etc.) is apparently too small. We’ll have to look into that, why this happens with some videos and not with others.
The empty warning message is due to a typo in our code (otherwise the message would read “Could not create an image.”, without further details).

Fur the purpose of saving several video stills, you could temporarily switch to the JavaFX media player (via Edit->Preferences->Edit Preferences... panel Platform/OS), (re-)open the file and save the stills with that framework (works with some videos that fail in the default player).