The session file records the sample rate that each audio file was saved at. Use it. This is a fix to part of https://code.soundsoftware.ac.uk/issues/970, but it also replaces the commit at https://code.soundsoftware.ac.uk/projects/svapp/repository/revisions/9554c19c42fd with a fix to the earlier bug http://sourceforge.net/p/sv1/bugs/107/. I think this is a better way than the earlier code.