[PD] howto play soundfiles from harddisc with adjustable speed?

[errorsmith]

Hello,
I am looking for an external that can play soundfiles just like readsf~ but
with an adjustable speed and with an adjustable position offset.
I tried the winport of sfread~
(http://www.akustische-kunst.org/puredata/winport/) but besides that the
readout doesn't have an interpolation , which leads to loud artefacts, it
seems that the longer file is played the more quantized is the speed
parameter, means that its resolution gets more coarse. So that after a
minute the file is played with speed one although I set the speed to .9.

greetings,

erik