[FFmpeg-user] Is there a way to determine the last valid value for -ss?

Hey folks, I've got a video that appears to be 00:00:30.03: https://pastebin.com/XRzdbQ0e When I try to extract a thumbnail using "ffmpeg -ss 30 -i example.mp4 -vframes 1 thumbnail.jpg" it fails with "Output file is empty, nothing was encoded(check -ss / -t / -frames parameters if used)": https://pastebin.com/uxHC2GzY It looks like any value for -ss over 29.988312̅9 fails. Is there a way to determine the last valid value for -ss?