Hello pomah,
Brett's answer is correct, as SigmaDSP is not yet capable of the complex algorithms that make transparent-sounding pitch shift possible. SigmaDSP started out with simple audio post-processing, such as equalization. Since then it has grown into increasingly advanced applications. We hope to see this continue in the future as both more powerful chips and sophisticated algorithms become available. Even now some advanced functions have been implemented with what SigmaDSP can already do -- whether these work well enough depends on the particular application.
A pitch-shifting block is already available in SigmaStudio's toolbox under ADI Algorithms. It's not up to processing music (for example, as a karaoke key changer). However, your need for 0.5x and 2x settings makes me wonder if you had voice playback in mind. If so, might as well give it a try:
I ran a voice recording through Audacity's speed change effect to produce slowed-down and sped-up speech, then ran the result through the Pitch Transposer on a AD1940 eval board. It sounded pretty natural on the sped-up material, not so much for slowed-down -- but either way the speech was intelligible.
Best regards,
Bob