‘Apparently’ there is also freemake which, unlike 3GP to DVD Converter is free (so at least fits the bill - of zero - better than Kien’s answer IMO) but may be difficult to use with “personal experience” that 3GP to DVD is much easier – except that the “personal experience” turns out to be just an audit trap (that I failed for trying to improve the “answer” via an edit). Yes it was a short answer – but still longer than the one accepted here.
So I have no experience of freemake but it does seem to be another option (and valid as an answer, whether or not correct).