Hi Harald
I will digest and respond more fully to all messages (received several today), but I wanted to shout out one thing now, in response to this comment that you made:
> I think the only one really fluent in that kind of topic would be
> tnt/sylvain.
Sylvain is one of the folks to whom we owe a debt, he blazed a good bit of the trail for us in the (de)interleave code in ysf:
$ grep -r Sylvain .
./op25/gr-op25_repeater/apps/tx/doc.html:Too many to list; thanks to Matt Ames, Pavel Yazev, Jonathan Naylor, unknown author(s) of DSD (DSDAuthor), Mathias Weyland, Sylvain Munaut; undoubtedly others.
./op25/gr-op25_repeater/lib/ysf_const.h:// I hold Sylvain Munaut in high esteem for figuring this out.