Interview process from initial contact to final decision was 3 months. I had 4 skype interviews and then flown out for a day of interviews. Each interviewer had technical problems to be solved. It's a small team in a small town, and they do some really cool stuff. The guys are very nice and will help you through the problems as necessary. They will allow you to code on a computer, which is so nice in an interview. Be able to throw together some quick C++ test code, or better yet, write some python to really impress these guys.
Know your C++ containers! Know some simple threading terminology. Keep up on your DSP basics.