It seems that many conversion programs cannot handle sources with mono audio. This is an old issue, it has nothing to do with AVStoDVD itself, but it would be nice to have some kind of an automatic workaround to avoid the situation that after the whole encode is finished you notice that the resulting DVD is not working due to a screwed-up audio stream.
I tested a couple of MP4 sources (AVC video, mono AAC audio). AVDtoDVD always prefers DirectShow over ffms2 as long as a DS source filter and a splitter are present. I have ffdshow and Haali installed, so AVStoDVD uses DirectShow for these files.
The resulting DVD contains audio at half speed. Sounds very interesting at times (especially when the source is an adult clip), but mostly this effect is not what you want...
I experimented a little, and for me forcing ffms2 as the source filter always worked (using DS and forcing stereo output did not work).
Do you think that automatically using ffms2 whenever a mono audio source is detected would be a good idea? Or is there a better way?
Cheers
manolito