>Think about writing a function that is a simple interpolator/
>decimator. For example a 3:2 interpolator/decimator program would
>interpolate by a factor of three and then decimate by a factor of two.
>The trick is to count through the phases and know where the zeros are,
>so you won't waste time computing with zeroes. Once you have such a
>routine written then you can simply cascade multiples of these with
>different/similar interpolation/decimation ratios to arrive at
>essentially any rational transformation you need. The other part is to
>design your FIR filter knowing where the overlap and don't car regions
>fall. I did this years ago and it worked quite well. I even had the
>code take the impulse response and break it up into its various
>phases.
>
>IHTH,
>
>Clay

Clay,

Thanks for your reply. The problem I am having is that doing cascade
seems to take more cpu than just doing one stage, I think due to loopin
through each sample multiple times. For example, doing the followin
multistage cascade, 2:1, then 80:147, seems to take more cpu than jus
doing 160:147 sample rate conversion? Is there a way to do the multistage
on one function call, not having to iterate through each sample multipl
times?