Historically, len_mult was meant to be a guide to let you know if you
needed more memory allocated than your original sound data required.
Should we deviate from SDL’s current behaviour? Thoughts?We already deviate from SDL’s current behaviour, since converting between
arbitrary sample frequencies violates the “buffer length has to be a power
of two” rule. So I don’t see any reason to needlessly cling to the SDL way,
if we can think of any better one. I doubt this code will make it back into
any 1.x version of SDL anyway.
We can do some kind of zero padding. Hmm… it doesn’t combine with the
loop stuff 
Did you think, the later is useful, anyway? Is it used in games? Perhaps
some repeating sound,
like walking, raining, machine-gun fire or something like that. I think
I’ve seen a similar function
in the win32 api.
Frank