Ambarella’s share price is volatile enough to cause seasickness. I’d be reluctant to buy at the current price. You’ll be relatively safe buying in the 30’s or 40’s, and the stock has been in that range several times in the past year, as recently as June.
While it’s shown excellent annual earnings growth through 2015, the last several quarters have shown a downhill trend. This is at least partly because of two things - supplier Sony’s shortage of camera sensors, and customer GoPro’s lower sales of video cameras.