Thanks for the reply.
So I take it from the reply, there's not (I know it's a long shot) a
'simple' way of converting an iPod linux codec to a Rockbox codec - i.e.
it requires me to actually understand both the Rockbox codec system and
the method in which a spectrum .tzx file works.
There's no 'easy way', no. And yes, to port or write a codec for Rockbox
you would need to understand how the Rockbox codec system works - and also
either how the .tzx file works, or how the iPod linux codec works -- but
take a look at the source code for a "simple" codec in Rockbox (e.g. wav?)
and it shouldn't be too hard.
d